Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 5 May 2021 – 11 May 2021

Aira – Kyushu (Japan) : JMA reported that during 3-10 May incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. There were four explosions and four non-explosive events during 3-7 May, producing ash plumes that rose as high has 2.5 km above the summit and ejecting bombs 0.8-1.1 km away from the crater. Very small eruptive events were recorded during 7-10 May. The sulfur dioxide emission rate was 1,300 tons per day on 19 May. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 4-6 May that sent ash plumes to 2.5 km (8,200 ft) a.s.l. and drifted N and SE. A thermal anomaly was identified in satellite data on 5 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Fuego – Guatemala : INSIVUMEH reported that 5-12 explosions per hour were recorded during 4-11 May at Fuego, generating ash plumes as high as 1.1 km above the crater rim. Shock waves sometimes rattled buildings around the volcano. Ashfall was reported daily in several areas downwind, including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Sangre de Cristo (8 km WSW), and San Pedro Yepocapa (8 km NW). Block avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Las Lajas (SE), and Honda drainages, often reaching vegetated areas. Explosions ejected incandescent material 100-450 m above the summit during 4-8 May.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Karymsky was visible in satellite images during 29-30 April and 1 May; weather clouds prevented observations during 2-7 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kilauea – Hawaiian Islands (USA) : HVO reported that the W vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake at a low rate during 5-11 May through a submerged inlet. The depth of the lake was 229 m by 11 May. Lava continued to circulate in the W part, though the active area continued to shrink. The E half of the lake remained solidified and comprised about 93 percent of the total area, based on thermal measurements acquired on 16 April. The sulfur dioxide emission rate was 200-300 tons per day during 5-7 May, and 150 tons per day on 10 May, continuing a downward trend that began in mid-April. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Krysuvik-Trolladyngja – Iceland : IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 5-11 May. On 2 May pulsating high jets of lava from crater 5 prompted authorities to widen the restricted zone because; ash and lava could be deposited several hundred of meters away. Cycles of lava jetting and effusion periodically continued during 3-7 May, with lava steadily enlarging the flow field. By 4 May the area of the flow field had grown to 1.41 square kilometers, and the total volume erupted was 23 million cubic meters. Activity was quiet for a period of time during 8-9 May, though IMO noted that fountaining quickly resumed during the morning of 9 May. High jets of lava occurred every 10 minutes, sometimes with jets rising as high as 300 m. Tephra (a few centimeters in diameter) was deposited as far as 1 km from the vent and small amounts of tephra were reported in Gríndavík. Hot deposits have caused small vegetation fires within a few hundreds of meters around the eruption site. On 10 May gas plumes rose higher than 2 km a.s.l. The eruption area was closed due to local wildfires and unfavorable wind conditions. Very high fountains were visible in Reykjavik. On 11 May lava fountains again rose up to 300 m tall and were seen from the capital. The cone had grown to about 50 m high. The Aviation colour Code remained at Orange due to the lack of ash and tephra emissions.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that mostly white plumes from Lewotolok rose as high as 600 m and drifted SE, W, and NW during 4-11 May. Gray-and-white plumes rose 500 m and drifted W, NW, and SE on 6 and 8 May. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both continued to extrude lava during 30 April-6 May. The SW rim lava-dome volume was an estimated 1.1 million cubic meters on 2 May, with a growth rate of about 17,000 cubic meters per day, and continued to shed material down the flank. A total of 12 pyroclastic flows traveled a maximum of 2 km down the SW flank. Incandescent avalanches, recorded 74 times, traveled as far as 2 km down the SW flank and twice went 600 m SE. The volume of the summit lava dome was 1.7 million cubic meters on 2 May, with a growth rate of about 14,000 cubic meters per day. Electronic Distance Measurement (EDM) data showed a distance shortening between points in the NW at a rate of 0.6 cm per day, indicating minor inflation. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the summit.

Pacaya – Guatemala : INSIVUMEH reported that during 4-11 May the lava flow on Pacaya’s N flank continued to advance, lengthening from 2.1 to 2.4 km, and spreading laterally in some areas. Incandescent blocks detached from the flow, especially along the flow margins and steep slopes. Occasional explosions at the vent (near Cerro Chino) ejected incandescent material as high as 100 m. Around 0600 on 6 May explosions at the summit produced ash plumes that drifted S. Dense ash plumes were visible drifting W and SW during 7-9 May. On 11 May an advancing lava flow on the SW flank was 2.3 km long.

Sangay – Ecuador : IG reported a high level of activity at Sangay during 5-11 May. Seismicity was characterized by 3-28 daily explosions, long-period earthquakes, lahar events, and signals indicating emissions. Weather clouds and rain sometimes prevented visual observations of the volcano, especially during 8-9 May. Based on the Washington VAAC and occasional webcam images, ash plumes were visible during 4-8 and 10 May rising as high as 2 km above the summit and drifting mainly NW, W, and SW. Eruptions during midmorning and again around noon on 7 May produced ash plumes that rose 2.3 km and drifted WSW; higher plumes rose 5.4 km and drifted NW. Notable ashfall was reported in multiple places in the afternoon; in Guamote (40 km WNW), in Riobamba, and Alusí. A lava flow descended the SE flank. Minor amounts of ash fell in parts of the Guayas province in the morning of 8 May. The seismic network recorded lahar signals during 7-10 May.

Santa Maria – Guatemala : INSIVUMEH reported that during 4-11 May daily explosions at Santa María’s Santiaguito lava-dome complex generated ash plumes that rose as high as 1.1 km above the summit and drifted W, SW, and S. Collapses of blocky lava from Caliente dome sent avalanches down the SE, S, SW, and W flanks, sometimes reaching the base, and causing minor ashfall around the volcano. Ashfall was also reported in San Marcos (8 km SW) and Loma Linda Palajunoj (6 km WSW) during 5-6 and 10-11 May.

Semeru – Eastern Java (Indonesia) : PVMBG reported that Semeru continued to erupt during 4-11 May. Avalanches of material traveled 200-300 m SE down the Kobokan drainage on 6 May. Gray-and-white plumes rose 200-500 m above the summit and drifted S during 8-9 May. Avalanches of material traveled as far as 700 m down the Kobokan drainage. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 5 km in the SSE sector.

Semisopochnoi – Aleutian Islands (USA) : AVO lowered the Aviation colour Code to Yellow and the Volcano Alert Level to Advisory for Semisopochnoi on 7 May, noting that no ash emissions had been observed nor explosions recorded since 26 April. Sulfur dioxide emissions were recorded on 1 and 5 May, signifying continued unrest. Steam plumes were visible rising from the N crater of Mt. Cerberus on 7 May.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 30 April-7 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 4-11 May. Weather conditions sometimes prevented visual observations of the volcano, though white fumarolic plumes were visible almost daily rising as high as 500 m above the summit and drifting in multiple directions. Daily avalanches descended 500-1,500 m down the E and SE flanks. At 1119 on 6 May an ash plume rose 2 km above the summit and drifted E. At 0908 and 1519 on 7 May ash plumes rose 3 km and drifted E. Ash plumes rose 1-2.8 km and drifted E, WNW, and W at 1044, 1656, and 1841 on 8 May; plumes were also seen on 9 May. At 0747 on 10 May an ash plume rose 2.5 km and drifted SW. Ash plumes on 11 May rose 700 m and drifted W at 0712, and rose 1.5 km and drifted E at 1428. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Soufriere St. Vincent – St. Vincent : On 6 May government authorities lowered the Alert Level to Orange for Soufrière St. Vincent (often simply referred to as “La Soufriere”) based on recommendations from University of the West Indies Seismic Research Centre (UWI-SRC). The public was allowed to return to their homes in the Yellow and Orange zones, though access to the Red Zone remained restricted. UWI-SRC noted that over the previous few days continuing lahars had mobilized boulders 5 m in diameter and were steamy in areas where they contacted hot deposits. A small lahar signal was recorded at 0740 on 7 May. Sulfur dioxide emissions were measured from a boat near the W coast, yielding a flux of 208 tons per day on 9 May. Seismicity remained low through 11 May with only a few long-period earthquakes recorded by the seismic network.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that 35 explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 2.4 km above the crater rim during 30 April-7 May. Large volcanic bombs were ejected 700 m from the crater. Crater incandescence was visible nightly. The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 5 May 2021 – 11 May 2021

Bulusan – Luzon (Philippines) : PHIVOLCS stated that unrest at Bulusan had increased, noting that 62 volcanic earthquakes were recorded during 7-10 May and 124 were recorded during 10-11 May. Inflation of the upper flanks first recorded on 6 March in tilt data was sustained. GPS data indicated short-term inflation starting in late February, though the long-term pattern since July 2019 showed deflation. The data suggested shallow hydrothermal processes. The Alert Level for Bulusan was raised to 1 on 11 May, reflecting abnormal conditions, and the public was reminded not to enter the 4-km-radius Permanent Danger Zone (PDZ).

Nevados de Chillan – Chile : SERNAGEOMIN noted that sulfur dioxide emissions and thermal anomalies at Nevados de Chillán’s Nicanor Crater had both increased in March, and inflation began on 27 March. During the second half of April the dome grew at a higher rate, with growth concentrated on the W part. The dome was 66 m high at the center. The L5 lava flow advanced and was about 940 m long, and 50 m thick near the flow front. The effusion rate increased on 28 April. During 2-5 May activity was characterized by increased crater incandescence and a series of intense explosions that destroyed part of the summit lava dome. Dense ash plumes rose above the crater. Block-and-ash flows traveled less than 400 m down the NE flank and pyroclastic flows traveled short distances SW. During 4-5 May the effusion rate increased and the L5 lava flow advanced. A new lava flow (L6) emerged on 5 May from the summit crater and descended 100 m down the NE flank. A high-temperature elongated deposit in between the L5 and L6 flows was visible in infrared images. The Alert Level remained at Yellow, the second lowest level on a four-colour scale. ONEMI stated that Alert Level Yellow (the middle level on a three-colour scale) remained in place for the communities of Pinto and Coihueco, noting that the public should stay at least 2 km away from the crater.

Piton de la Fournaise – Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise continued during 4-11 May. Both craters were active, producing lava flows that mainly traveled though lava tubes. Lava emerged from the end of the flow field, advancing E to 1,200 m elevation by 8 May, and setting fire to local vegetation. Minor inflation of the summit area was recorded. Lava fountaining was weak at the smaller vent to the SE and a small lava pond continued to occupy the crater of the larger cone, just NW a higher elevation. Gas plumes rose from both craters, though the plumes from the smaller crater were denser. An 11 May report stated that the larger cone was 35 m tall and 226 m in diameter at its base. The Alert Level remained at 2-2.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 28 April 2021 – 4 May 2021

Aira – Kyushu (Japan) : JMA reported that during 26 April-3 May incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. There was a total of 10 explosions, producing ash plumes that rose as high has 2.4 km above the summit and ejected bombs 1.3-1.7 km away from the crater. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 22-24 April that sent ash plumes to 3 km (10,000 ft) a.s.l. and drifted NE and SW. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kilauea – Hawaiian Islands (USA) : HVO reported that the W vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 28 April-4 May through a submerged inlet. The depth of the lake was about 227 m and lava continued to circulate in the W part, though the active area continued to shrink. The E half of the lake remained solidified and comprised about 93 percent of the total area, based on thermal measurements acquired on 16 April. The sulfur dioxide emission rate was 250 and 475 tons/day on 30 April and 2 May, respectively, continuing a downward trend that began in mid-April; the recent rates suggested that the effusion rate had also decreased. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Krysuvik-Trolladyngja – Iceland : IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 28 April-4 May. According to a news source, activity at the S vent of the fifth cone, which had opened on 13 April with N and S vents, intensified at around 2030 on 26 April. Fountaining became more explosive and lava was jetted 40-50 m high. The lava-flow rate significantly increased; lava flowed S then E and descended a valley into Meradalir. By 29 April activity had intensified at the fifth cone where lava ejections reached 250 m high, but had ceased at the others. By 1 May lava flows had traveled N in Meradalir and connected to the flows that had previously descended into the valley from a fissure that opened on 5 April. IMO noted that fountaining at the vent was steady until around 0000-0100 on 2 May when it became more pulsating. Resting periods of 1-2 minutes were punctuated by intense fountaining reaching 100-150 m high for periods of 8-12 minutes. Gas plumes with minor amounts of ash rose 800-900 m a.s.l. A news source noted that on 2 May lava fountains rose over 300 m, the highest to date, and were seen from Reykjavik. Ejecta set fire to vegetation on the hill to the S of the vent, causing a smoke plume. The Aviation colour Code remained at Orange due to the lack of ash and tephra emissions.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that white plumes from Lewotolok rose as high as 500 m and drifted SE, SW, and W on most days during 27 April-3 May. Gray-and-white plumes rose 500 m and drifted W on 30 April and 2 May. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both continued to extrude lava during 23-29 April. The SW rim lava dome had an estimated volume of 1,141,850 cubic meters on 28 April, with a growth rate of about 11,900 cubic meters per day, and continued to shed material down the flank. A total of 12 pyroclastic flows traveled a maximum of 2 km down the SW flank. Incandescent avalanches, recorded 113 times, traveled as far as 2 km down the SW flank. The volume of the summit lava dome was 1,794,000 cubic meters on 28 April, unchanged from the previous week. Electronic Distance Measurement (EDM) data showed a distance shortening between points in the NW at a rate of 0.5 cm per day, indicating inflation. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the summit.

Pacaya – Guatemala : INSIVUMEH reported that during 27-29 April occasional explosions at Pacaya’s Mackenney Crater ejected incandescent material as high as 250 m above the summit. On 27 April a lava flow emerged from a new fissure on the upper SE flank traveled 200 m. At around 0500 on 29 April the seismic network recorded signals indicating a change from mostly explosive to mostly effusive activity. At around 0645 a new fissure opened on the N flank, producing a lava flow that rapidly traveled N towards Cerro Chino and then turned S and spread W and SW. Explosive activity at the fissure was minor during 29-30 April. By 3 May the flow was almost 2.1 km long, and continued to advanced W and SW at least through 4 May.

Semeru – Eastern Java (Indonesia) : PVMBG reported that at 0740 on 28 April an ash plume from Semeru rose 600 m above the summit and drifted SW. The next day, at 0550, an ash plume rose 400 m and drifted S. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 5 km in the SSE sector.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 23-30 April. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 28 April-4 May. Weather conditions sometimes prevented visual observations of the volcano, though white fumarolic plumes were visible almost daily rising as high as 500 m above the summit and drifted in multiple directions. At 0728 on 28 April an ash plume rose 1 km and drifted SSW. At 1810 an ash plume rose 1 km and drifted SSE and an incandescent avalanche descended 1.5 km down the SSE flank. At 2346 an ash plume rose 1.5 km and drifted W and SW, and another incandescent rockfall traveled 1.5 km SSE. Eruptive events produced ash plumes that rose 500-1,000 m above the summit during 30 April-1 May. Avalanches of material traveled as far as 1.5 km E and 1 km SE during 1-3 May. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Soufriere St. Vincent – St. Vincent : University of the West Indies Seismic Research Centre (UWI-SRC) reported that seismicity at Soufrière St. Vincent (often simply referred to as “La Soufriere”) remained low during 28 April-4 May, with a few long-period, hybrid, and volcano-tectonic earthquakes recorded daily. Multiple significant lahars were generated by rainfall during 28-29 April. Lahars likely descended all valleys in the Red and Orange zones, and some were hot and visibly steaming. Trees brought down by lahars were swept to the sea; floating logs created hazardous conditions for small boats along the coastline. UWI-SRC and the National Emergency Management Organisation (NEMO) both warned the public to stay away from drainages and areas prone to flooding, and noted that lahars have caused notable erosion and damage to drainages and parts of the coastline. Smaller lahars were recorded during the mornings of 30 April and 1 May. Multiple lahars were detected in likely all the volcano’s drainages for a period of about six hours on 3 May, with the most intense lahars occurring during 1100-1200. Sulfur dioxide emissions were measured from a boat near the W coast, yielding a flux of 1,036 tons per day. Photos showed people in Sandy Bay shoveling off ash from rooftops on 4 May. The volcano Alert Level remained at Red.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that 45 explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 1.7 km above the crater rim during 23-30 April. Large volcanic bombs were ejected 400 m from the crater. Nighttime crater incandescence was visible during 24-25 April. The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Taal – Luzon (Philippines) : PHIVOLCS reported that unrest at Taal continued during 27 April-4 May. Low-level background tremor that had begun at 0905 on 8 April continued, along with 2-26 daily low-frequency events and 5-37 daily volcanic earthquakes during 28 April-2 May. One hybrid event was detected during 28-29 April. Diffuse steam plumes from fumarolic vents in Main Crater rose 5-10 m on most days. Average daily sulfur dioxide emission rates were in the 1,452-3,191 tonnes per day range. Upwelling of hot volcanic fluids in the crater lake was accompanied by steam plumes that were 300-600 m tall on 27 April, 30 April, and 4 May. The Alert Level for Taal remained at 2 (on a scale of 0-5). PHIVOLCS strongly recommended no entry onto the island, and access to the Main Crater and Daang Kastila fissure (along the walking trail) was strictly prohibited.

Whakaari/White Island – North Island (New Zealand) : GeoNet reported that a brief period of low-energy tremor and acoustic signals was recorded at Whakaari/White Island beginning at 2230 on 29 April. During an overflight on 30 April scientists did not observe new deposits near the active vent or thermal anomalies at the active vent area. Gas-emission rates had been relatively unchanged since March. The brief period of increased activity was likely caused by a series of low-energy subterranean explosions, similar to activity observed in mid-February and early-mid March. Seismic tremor remained at background levels. The Volcanic Alert Level remained at 1 and the Aviation colour Code remained at Green.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 28 April 2021 – 4 May 2021

Asosan – Kyushu (Japan) : Volcanic tremor amplitude increased at Asoson at around 2100 on 2 May, prompting JMA to raise the Alert Level to 2 (on a scale of 1-5) at 2255. The public was warned to stay at least 1 km away from the crater. Sulfur dioxide emissions were low, at 200 tons per day on 3 May, and white steam plumes rose as high as 300 m above the crater rim.

Dieng Volcanic Complex – Central Java (Indonesia) : PVMBG reported that a phreatic eruption at the Sileri Crater lake (Dieng Volcanic Complex) occurred at 1825 on 29 April, ejecting rocks 200 m S and E and mud 400 m S and 300 m E. According to a news article a local road was temporarily closed because rocks (about 10 cm in diameter) from the eruption were scattered along the road and the mud made conditions slippery. The closest residents are 1 km away. The Alert Level remained at 1 (on a scale of 1-4), and the public was warned to stay 500 m away from the crater rim.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Karymsky was visible in satellite images during 22-23 and 29 April. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Piton de la Fournaise – Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise continued during 28 April-4 May, though inclement weather obscured visual observations during most of the week. Both craters were active, producing lava flows that mainly traveled though lava tubes. Lava emerged from the end of the flow field, advancing E and setting fire to local vegetation. Minor inflation of the summit area was recorded. Lava fountaining was weak at the smaller vent to the SE during 3-4 May and a small lava pond occupied the crater of the larger cone, just NW at the higher elevation. On 4 May weak fountaining at the smaller cone occasionally ejected material just above the crater rim and the pond was active in the larger crater. The lava flow advanced another 180 m, reaching 1,500 m elevation. According to a news article two students in their 20s were found dead in the caldera on 22 April, near the active cones. The cause of death was not immediately known. The Alert Level remained at 2-2.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 21 April 2021 – 27 April 2021

Aira – Kyushu (Japan) : JMA reported that during 19-26 April incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. There was a total of 16 explosions, producing ash plumes that rose as high as 2.3 km above the summit and ejected bombs 1-1.3 km away from the crater. The sulfur dioxide emission rate was somewhat high at 1,800 tons per day on 21 April. An explosion at 0109 on 25 April produced what was initially thought to be a pyroclastic flow, triggering JMA to warn residents beyond a 2-km radius to be cautious and vigilant. Scientists conducting field observations later that day did not observe pyroclastic flow deposits or damaged vegetation, and concluded that the plume phenomenon was generated by winds. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 16-18 and 22 April that sent ash plumes to 3 km (10,000 ft) a.s.l. and drifted NE, E, and SW. Ash fell in Severo-Kurilsk on 16 April. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Etna – Sicily (Italy) : INGV reported that during 19-25 April activity at Etna was mainly characterized by gas emissions rising from the summit craters, though inclement weather conditions often prevented visual observations. Bocca Nuova in particular produced frequent steam puffs. A strong explosion at 0030 on 25 April from the E vent of Southeast Crater (SEC) ejected incandescent material up to 350 m above the crater rim. An ash plume dispersed to the S.

Fuego – Guatemala : INSIVUMEH reported that 5-14 explosions were recorded per hour during 21-27 April at Fuego, generating ash plumes as high as 1.1 km above the crater rim. Shock waves rattled buildings around the volcano, especially in areas as far as 20 km W and SW. Block avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Las Lajas (SE), and Honda drainages, often reaching vegetated areas. Ashfall was reported on most days in several areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Sangre de Cristo (8 km WSW), and San Pedro Yepocapa (8 km NW). Explosions ejected incandescent material 100-400 m above the summit almost daily.

Kilauea – Hawaiian Islands (USA) : HVO reported that the W vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 21-27 April. Lava flowed at a low rate from the main vent into the lake through crusted-over channels and submerged inlets. The depth of the lake was about 226-227 m and lava continued to circulate in the W part, though the active area continued to shrink; the E half of the lake remained solidified. Lava sometimes overflowed the margins of the lake. The sulfur dioxide emission rate was 350, 550, 300, and 350 tons/day on 21, 22, 23, and 24 April, respectively. The rates were the lowest measured during the eruption, though elevated above the levels recorded in the months before the start of the eruption (20 December 2020). The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Krysuvik-Trolladyngja – Iceland : IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 21-27 April. A M 4.1 earthquake was recorded at 2305 on 21 April about 6 km WSW of the fissures and followed by several aftershocks; it was the largest on the Reykjanes Peninsula since 15 March, before the eruption began. The average lava-flow rate was calculated by the University of Iceland’s Institute of Earth Sciences using photographs most recently collected during an overflight on 26 April. They reported that during the previous five days the flow rate from all of the active craters averaged just over 6 cubic meters per second; the average rate during the 38 days of the eruption was 5.6 cubic meters per second. The area of the flow field was 1.13 square kilometers, the total volume was over 18.4 million cubic meters, with an average thickness of just over 16 m. The Aviation colour Code remained at Orange due to the lack of ash and tephra emissions.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the eruption at Lewotolok continued during 20-27 April. Black, gray, and white plumes rose as high as 1 km above the summit and drifted E, SE, and W on most days. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both continued to extrude lava during 16-22 April. The SW rim lava-dome volume was an estimated 1,069,600 cubic meters on 21 April, with a growth rate of about 11,900 cubic meters per day; the dome continued to shed material down the flank. A total of nine pyroclastic flows traveled a maximum of 1.8 km down the SW flank. Incandescent avalanches, recorded 144 times, traveled as far as 1.6 km down the SW flank and twice down the SE flank as far as 400 m. The volume of the summit lava dome was 1,794,000 cubic meters on 22 April. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the summit.

Pacaya – Guatemala : INSIVUMEH reported that during 20-21 April explosions at Pacaya’s Mackenney Crater generated minor gas-and-ash plumes that rose 250 m above the summit and drifted S and SW. The lava flow on the SW flank continued to be active, though did not advance. White gas plumes were visible the next day rising as high as 200 m. On 23 April lava effusion ceased. The lava flows on the SW flank remained hot and gas plumes rose from parts of the flow; no advancement was visible through 27 April. Gray-and-white emissions were visible during 24-27 April, rising 100-200 m above the summit and dispersing S and SW. Occasional minor explosions ejected incandescent material 50-150 m high during 26-27 April.

Semeru – Eastern Java (Indonesia) : PVMBG reported that during 21-22 and 24-25 April ash plumes from Semeru rose 500-700 m above the summit and drifted SW, S, and SE. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 5 km in the SSE sector.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 16-23 April. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 21-27 April. Weather conditions sometimes prevented visual observations of the volcano, though white fumarolic plumes were visible almost daily rising as high as 700 m above the summit and drifted E and SE. Pyroclastic flows traveled 2 km on 21 April. Avalanches of material traveled 1 km E and SE during 23-24 April. Ash plumes rose 2 km above the summit on 24 April and to 1 km on 25 April, drifting ESE both days. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Stromboli – Aeolian Islands (Italy) : INGV reported that during 19-25 April activity at Stromboli was characterized by ongoing explosive activity from Area N (North Crater area) and in Area C-S (South-Central Crater area), though sometime weather conditions prevented visual observations. Explosions from two vents in the N1 vent (Area N) ejected lapilli and bombs 250 m high, and produced minor ash emissions. Explosions at N2 vents (Area N) averaged 11-14 events per hour. Periods of visible spattering were most notable on 24 April. Explosions from at least three vents in Area C-S occurred at a rate of 1-5 events per hour and ejected coarse material more than 250 m high.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that incandescence from Suwanosejima’s Ontake Crater was occasionally visible at night during 16-23 April. Five explosions generated ash plumes that rose as high as 1.7 km above the crater rim and ejected bombs 600 m away. The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Villarrica – Chile : SERNAGEOMIN reported that during 1-15 April gas-and-steam emissions with no or very small amounts of ash rose from Villarrica to heights less than 1.2 km above the crater rim. Crater incandescence was not visible at night and sulfur dioxide emissions were low. Observations from multiple sources suggested that the lava lake level was lower, decreasing the likelihood that material ejected by minor explosions would reach beyond 100 m from the crater. The Alert Level was lowered to Green on 23 April, the lowest level on a four-colour scale. ONEMI declared a “Preventative Early Warning” for the municipalities of Villarrica, Pucón (16 km N), Curarrehue, and the commune of Panguipulli, and the exclusion zone for the public of 100 m around the crater.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 21 April 2021 – 27 April 2021

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Karymsky was visible in satellite images 16-17 and 22 April. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Piton de la Fournaise – Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise continued during 21-27 April, though inclement weather conditions obscured visual observations most of the week. The average lava-flow rate was between 1.2 and 8.3 cubic meters per second during 16-23 April. The flow rates were estimated based on the gas-emission rates, though weather conditions may have affected the accuracy of the measurements. Lava continued to mostly flow in lava tubes; some flows thickened and parts of the flow field widened. The longest flow was 3.2 km long and the maximum width was 750 m, unchanged from the previous week. The flow field was mapped using a satellite image acquired on 24 April. The Alert Level remained at 2-2.

Semisopochnoi – Aleutian Islands (USA) : Eruptive activity at Semisopochnoi gradually increased during 21-22 April based on satellite and infrasound data; ash emissions were first seen in satellite images at 1800 on 21 April and were continuous at least through 1348 on 22 April. Plumes rose to 2.4 km (8,000 ft) a.s.l. and drifted 80 km S. Sulfur dioxide emissions were also detected in satellite images on 22 April. Cloud cover mostly obscured views during 23-24 April, though possible minor ash emissions were sometimes visible. Low-level ash plumes drifting S were occasionally identified in satellite images during 24-26 April. Dense weather clouds prevented views for most of 26 April and the next day. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Soufriere St. Vincent – St. Vincent : University of the West Indies Seismic Research Centre (UWI-SRC) reported that eruptive activity at Soufrière St. Vincent (often simply referred to as “La Soufriere”) was relatively low during 21-27 April with the exception of one explosive period. During 20-21 April seismicity was characterized by a few rockfalls and volcano-tectonic (VT) earthquakes, and an increasing number of small long-period (LP) and hybrid earthquakes. Sulfur dioxide emissions were again measured from a boat near the W coast, revealing a flux of 350 tons per day. At around 1108 on 22 April explosions produced an ash plume that rose as high as 8 km (26,200 ft) a.s.l. and drifted mainly N over the sea. High-level seismic tremor began at 1109 and lasted for about 20 minutes. Pyroclastic flows were generated early in the eruption and traveled down the W flank, reaching the sea within five minutes. Lahar signals were recorded later that day at about 2100. According to National Emergency Management Organisation (NEMO) the total number of displaced people was 13,154 by 21 April, with 6,208 people in 85 public shelters and 6,790 people (1,618 families) in private shelters. There were no casualties caused by the eruption. In a 22 April press release the Argyle International Airport announced that the ash cleanup was ongoing and that the Cargo Terminal was scheduled to open the next day. Seismicity dropped to low levels after the explosive event and remained at low levels through 27 April; only a few LP, hybrid and VT earthquakes were recorded. On 23 April the sulfur dioxide flux was 992 tons per day, recorded again from the W coast. A diffuse steam plume rose from the crater on 24 April. Satellite data most recently from 24 April, and seismic data suggested likely cycles of crater dome growth and destruction. During an overflight on 26 April scientists observed white steam plumes rising from several locations on the crater floor, though visibility was poor. No lava dome was visible, but a possible spine-like protrusion was seen through the clouds. Seismic signals indicating lahars were again recorded. Lahars in the Red and Orange zones were recorded by the seismic network at 0900 and 1000 on 27 April, during and after rainfall. The volcano Alert Level remained at Red.

Veniaminof – United States : AVO reported that eruptive activity at Veniaminof had declined during the previous few weeks; no emissions were visible after ash emissions on 5 April and seismicity continued to decline. On 21 April the Volcano Alert Level was lowered to Advisory and the Aviation colour Code was lowered to Yellow.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 14 April 2021 – 20 April 2021

Aira – Kyushu (Japan) : JMA reported that during 12-19 April incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. There was a total of nine explosions and one eruptive event. Ash plumes rose 1-2 km above the summit and bombs were ejected 800-1,300 m away from the crater. The sulfur dioxide emission rate was high at 2,400 tons per day on 12 April. The Alert Level remained at 3 (on a 5-level scale).

Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 13-20 April ash plumes from Dukono rose to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted E and NE. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 9-16 April that sent ash plumes to 3.6 km (11,800 ft) a.s.l. and drifted in multiple directions. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kadovar – Papua New Guinea : Based on satellite and wind model data, the Darwin VAAC reported that on 15 April ash plumes from Kadovar rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted W.

Kilauea – Hawaiian Islands (USA : HVO reported that the W vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 14-20 April. Lava flowed at a low rate from the main vent into the lake through crusted-over channels and submerged inlets. The depth of the lake was about 226-227 m and lava continued to circulate in the W part, though the active area continued to shrink; the E half of the lake remained solidified. Lava sometimes overflowed the margins of the lake. The sulfur dioxide emission rate was 950 tons/day on 14 April. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the eruption at Lewotolok continued during 13-19 April. Gray-and-white ash plumes rose as high as 1.5 km above the summit and drifted E and W. Rumbling was often audible. Incandescent material was ejected 300-1,000 m above the summit during 14-16 April. Incandescent material was ejected to the E during 9 and 11-12 April. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 4 km away from the summit crater.

Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both continued to extrude lava during 9-15 April. The SW rim lava-dome volume was an estimated 1,024,800 cubic meters on 15 April, with a growth rate of about 12,200 cubic meters per day, and continued to shed material down the flank. A total of six pyroclastic flows traveled a maximum of 1.8 km down the SW flank. Incandescent avalanches, recorded 119 times, traveled as far as 1.5 km down the SW flank. The volume of the summit lava dome was 1,681,000 cubic meters on 14 April. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the summit.

Popocatepetl – Mexico : CENAPRED reported that each day during 13-20 April there were 14-34 steam, gas, and ash emissions from Popocatépetl and periods of tremor lasting from 5-15 hours. Two volcanic earthquakes were recorded at 1054 and 2354 on 16 April. Minor crater incandescence was visible overnight during 17-18 April. A M 1.3 volcano-tectonic earthquake was recorded at 2057 on 18 April. The Alert Level remained at Yellow, Phase Two (middle level on a three-colour scale).

Raung – Eastern Java (Indonesia) : PVMBG reported that gray-and-white ash plumes rose 50-400 m above Raung’s summit during 13-14 April and drifted N, NE, E, and S. Emissions were white and rose as high as 400 m during 15-16 and 19 April. Weather conditions prented visual observations on some days. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Sabancaya – Peru : Instituto Geofísico del Perú (IGP) reported a daily average of 91 explosions at Sabancaya during 12-18 April. Gas-and-ash plumes rose as high as 2.3 km above the summit and drifted S, SW, NW, and N. Eight thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. Minor inflation continued to be detected near Hualca Hualca (4 km N). The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 12-km radius.

Sangay – Ecuador : IG reported a high level of activity at Sangay during 13-20 April. Seismicity was characterized by daily explosions, long-period earthquakes, lahar events, and signals indicating emissions. Weather clouds and rain often prevented visual observations of the volcano, though based on the Washington VAAC and webcam images, ash plumes were visible during 13-14 and 17-20 April rising 600-2,400 m above the summit and drifting mainly N, NW, and W. The seismic network occasionally recorded lahar signals, especially during 14-16 April. Ashfall was reported in Chimborazo (W) and Guamote (40 km WNW) on 17 April, and crater incandescence was visible through the night of 19-20 April.

Semeru – Eastern Java (Indonesia) : PVMBG reported that at 0650 on 19 April an ash plume from Semeru rose 400 m above the summit and drifted W. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 5 km in the SSE sector.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 9-16 April. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Sinabung – Indonesia : PVMBG reported that on 13 April eruptive events at Sinabung generated ash plumes that rose 500-1,600 m above the summit. Avalanches of material traveled 1-1.5 km. On 14 April gray ash plumes rose 500 m above the summit and avalanches traveled 500-700 m down the E and SE flanks. During 15-20 April white plumes were often seen rising as high as 700 m, though weather conditions sometimes prevented visual observations. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that incandescence from Suwanosejima’s Ontake Crater was visible at night during 9-16 April. Seven explosions generated ash plumes that rose as high as 1.5 km above the crater rim and ejected bombs 400 m away. Ashfall was reported in Toshima village (4 km SSW). The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Tanaga – Andreanof Islands (USA) : AVO reported that communication was reestablished with two seismic stations on Tanaga, making a total of four operational stations. On 19 April AVO changed both the Aviation colour Code and the Volcano Alert Level to Green and Normal, respectively, reflecting the resumption of seismically monitoring unrest.

Ugashik-Peulik – United States : AVO reported a loss of operation and communication with seismic stations that monitor Ugashik-Peulik, likely caused by snow cover. Both the Aviation colour Code and the Volcano Alert Level were changed to Unassigned on 19 April, reflecting the inability to locate earthquakes to detect unrest. Monitoring will continue with the remaining seismic stations, regional infrasound networks, lightning detection, and satellite images.

Ukinrek Maars – United States : AVO reported a loss of operation and communication with seismic stations that monitor Ukinrek-Maars, likely caused by snow cover. Both the Aviation colour Code and the Volcano Alert Level were changed to Unassigned on 19 April, reflecting the inability to locate earthquakes to detect unrest. Monitoring will continue with the remaining seismic stations, regional infrasound networks, lightning detection, and satellite images.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 14 April 2021 – 20 April 2021

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was visible in satellite images during 9-12 April; weather conditions obscured views during 13-16 April. An explosion at 1745 on 11 April produced ash plumes that rose to 4 km (13,100 ft) a.s.l. and drifted 112 km SSE. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Krysuvik-Trolladyngja – Iceland : IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 14-20 April. Lava flowed from about eight vents and the flow field continued to expand; on 14 April a new hiking trail (“A”) had been covered. Volcanic gas emissions were at dangerous levels during 14-15 April so the eruption site was closed to the public. At about 1500 on 17 April a new vent was confirmed to have opened. It was small and close to another crater, possibly the one that had opened on 13 April. Lava was not flowing from the northernmost crater (the first that had opened outside Geldingadalur) during 18-20 April. The eruption had been ongoing for 30 days by 17 April. Based on a report from University of Iceland’s Institute of Earth Sciences, the average lava-flow rate during the first 17 days of the eruption was 4.5-5 cubic meters per second but had increased to 7 cubic meters per second over the previous 13 days. During 12-18 April the flow rate was closer to 8 cubic meters per second, a slight increase over the recent average. By 19 April the area of the flow field was 0.9 square kilometers and the total volume was over 14 million cubic meters. IMO warned visitors that new fissures could open without adequate visible warning, especially in an area by Litla-Hrút, just S of Keilir, `where seismicity was concentrated. They also warned of increased gas emissions hazards. The Aviation colour Code remained Orange due to the lack of ash and tephra emissions.

Piton de la Fournaise – Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise continued during 14-20 April. Lava fountaining was visible from both cones on most days, though sometimes inclement weather prevented visual observations of the eruption site. During an overflight on 16 April scientists observed that the most distal part of the lava flows had stopped advancing. The larger and more northern cone was 28 m high. The cone at a lower elevation, about 100 m away, had two vents. The smaller cone fed lava flows that traveled though tubes and emerged after 100 m, continuing to advance as many surficial breakout flows. The total length of the flow field was about 3.5 km and the maximum width was 750 m. Sulfur dioxide emissions gradually increased between 400 and 859 tonnes per day during 9-12 April, peaked at 4,054 tonnes per day on 13 April, and then dropped to 2,100 tonnes per day on 14 April. OVPF estimated lava-flow rates based on the gas-emission rates, noting that weather conditions could affect the accuracy of the measurements. They estimated that the average flow rate in cubic meters per second was 20 during 9-10 April, an average of 24 with a maximum value of 59 on 13 April, 12.5 on 14 April, and 6.5-8.3 during 16-19 April. The Alert Level was raised to 2-2.

Soufriere St. Vincent – St. Vincent : University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the explosive eruption at Soufrière St. Vincent (often simply referred to as “La Soufriere”) continued during 14-20 April, though at a decreasing frequency. Explosions and pyroclastic flows were reported on 13 April, as well as lahars in the Sandy Bay area. During 14 April seismicity continued to be characterized by episodes of tremor, about 13-15 hours apart, separated by swarms of small, long-period (LP) earthquakes. An episode of tremor that began at 1135 was associated with increased explosive activity, though the emissions were gas rich and less energetic than previous events. Another episode of tremor began at 0230 on 15 April along with increased venting. Almost constant swarms of long-period and hybrid events were recorded through the day, punctuated by three brief episodes (less than 30 minutes) of low-level tremor. An episode of tremor began at 2100 and lasted 40 minutes, and was possibly associated with a minor increase in venting. For the first time sulfur dioxide emissions were successfully measured by ground-based instruments; scientists recorded 809 tons per day from a Coast Guard boat along the W coast. Periods of tremor and near-constant swarms of LP and hybrid events were recorded on 16 April. An explosion at 0615 on 16 April generated an ash plume that rose about 8 km (26,200 ft) a.s.l. and drifted W. A three-minute period of high-level tremor started at the same time and was flowed by over two hours of lower-level tremor. Sulfur dioxide emissions were again measured from the W coast, yielding a flux of 460 tons per day. The rate of LP and hybrid events dropped significantly at 2000. Sulfur dioxide plumes reached India. Occasional satellite images of the summit showed a series of changes to the new crater, centered in the SW part of the summit crater. By 17 April an Institut de Physique du Globe de Paris scientist reported that the crater was about 900 m N to S, at least 750 m E to W, and about 100 m deep based on RADAR data. Several vents were either visible or inferred from points of emissions. Sulfur dioxide emissions were 232 and 391 tons per day on 17 and 18 April, respectively. A period of high tremor began at 1649 on 18 April. An explosion produced an ash plume that rose to 8 km (26,200 ft) a.s.l. and drifted S and SW. This explosion occurred 52 hours after the last one and was the 30th since the explosive phase started. The period of tremor lasted until about 2100 and was followed by ongoing small LP and hybrid events. The rates of those events dropped again, at around 0100 on 19 April. One rockfall was detected by the seismic network at 0139, and two were noted the next day. At 0400 on 20 April a lahar was detected by the seismic network and lasted for 30 minutes; it possibly traveled down the SE flank. During 15-19 April NEMO reported details about the people that have evacuated. The total number of displaced people was 12,775 by 19 April, with 6,208 people in 85 public shelters and 6,567 people (1,800 families) in private shelters. There were no casualties caused by the eruption.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that an eruption at Semisopochnoi continued during 14-20 April. Sulfur dioxide emissions were identified in satellite images during 13-14 April. An explosion was recorded by the regional infrasound network at 0417 on 14 April, though weather cloud cover as high as 4 km (13,000 ft) a.s.l. prevented satellite confirmation of an ash plume. Ash emissions began during the morning of 15 April and continued through the day, drifting more than 350 km SE at altitudes as high as 6 km (20,000 ft) a.s.l. They did not decrease in intensity, so at 1915 AVO raised the Aviation colour Code to Red and the Volcano Alert Level to Warning. Sustained ash emissions continued on 16 April, though the plume rose as high as 3 km (10,000 ft) a.s.l. and winds pushed it N. Explosions were detected through the night and early in the morning. Minor ash deposits around the volcano were visible. Eruptive activity declined during 16-17 April; one clear satellite view suggested that activity had declined or ceased. At 1249 on 17 April AVO lowered the Aviation colour Code to Orange and the Volcano Alert Level to Watch. Several explosions were recorded during 17-19 April though weather clouds obscured views. Volcanic plumes were visible just above the weather cloud deck (situated at 3 km (10,000 ft) a.s.l.) and drifted S during 19-20 April. A few darker (possibly ash rich) plumes were visible in satellite data at 0700 and 1150 on 19 April and on 20 April.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 7 April 2021 – 13 April 2021

Aira – Kyushu (Japan) : JMA reported that at 0641 on 5 April and explosion at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) produced an ash plume that rose as high as 3 km above the crater rim and ejected material 800-1,000 m away from the crater. Five explosions were recorded during 9-12 April. The highest ash plume rose 2.1 km and bombs were ejected as far as 900 m from the crater. Crater incandescence was visible nightly. The Alert Level remained at 3 (on a 5-level scale).

Dukono – Halmahera (Indonesia) : PVMBG reported that during 6-10 April ash plumes from Dukono rose 100-700 m above the summit and drifted E, SE, and S. Weather conditions prevented visual observations during 11-12 April. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 2-9 April that sent ash plumes to 4.5 km (14,800 ft) a.s.l. and drifted in multiple directions. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Ibu – Halmahera (Indonesia) : PVMBG reported that during 6-13 April gray-and-white ash plumes from Ibu rose 200-1,000 m above the summit and drifted mainly N, E, and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater and 3.5 km away on the N side.

Kilauea – Hawaiian Islands (USA) : HVO reported that the W vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 31 March-6 April. Lava flowed at a low rate from the main vent into the lake through crusted-over channels and submerged inlets. The total depth of the lake measured about 226 m and lava continued to circulate in the W part; the E half of the lake remained solidified and expanded toward the W. The sulfur dioxide emission rate was 1,200 tons/day on 1 April. HVO field crews observed weak spattering from two areas at the W vent during 1-2 April. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 6-13 April. Gray-and-white ash plumes rose as high as 750 m above the summit and drifted in multiple directions. Incandescent material was ejected 300-500 m above the summit on most days and 500 m SE on 8 April. Incandescent material was ejected to the E during 9 and 11-12 April. Rumbling was occasionally audible. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 4 km away from the summit crater.

Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both continued to grow during 1-8 April. The SW rim lava-dome volume was an estimated 1,098,000 cubic meters on 7 April, with a growth rate of about 12,800 cubic meters per day, and continued to shed material down the flank. A total of 13 pyroclastic flows traveled a maximum of 1.5 km down the SW flank. Incandescent avalanches, recorded 119 times, traveled as far as 1.1 km down the SW flank. The summit lava dome had grown to 75 m tall. Minor ashfall was reported in Ngipiksari (8 km SSW), Klangon (4 km S), and Deles (3 km SE) on 3 April. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the summit.

Raung – Eastern Java (Indonesia) : PVMBG reported that daily gray-and-white ash plumes rose 50-600 m above Raung’s summit during 6-13 April and drifted mainly N, E, and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Semeru – Eastern Java (Indonesia) : PVMBG reported that the eruption at Semeru continued during 7-13 April, though weather conditions often prevented visual confirmation. Gray-and-white ash plumes rose as high as 500 m during 9 and 11-12 April. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 5 km in the SSE sector.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 2-9 April. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 6-13 April. Weather conditions sometimes prevented visual observations of the volcano, though white fumarolic plumes were visible almost daily rising as high as 700 m above the summit and drifting in multiple directions. An eruptive event on 7 April produced a gray ash plume that rose 1 km. Two eruptive events the next day generated ash plumes that rose as high as 700 m. Avalanches traveled as far as 1.5 km E and SE during 8-11 April. Ash plumes rose 500-1,000 m high on 10 April. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 7 April 2021 – 13 April 2021

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that the explosive eruption that began at Karymsky on 3 April continued through 11 April. A thermal anomaly was visible in satellite images during 2-6 April; weather conditions obscured views on other days. The 3 April explosion generated an ash plume that rose to 8.5 km (27,900 ft) a.s.l. and drifted 255 km NE. At 1745 on 11 April explosions produced ash plumes that rose to 4 km (13,100 ft) a.s.l. and drifted at least 65 km SE. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale) on 3 April.

Krysuvik-Trolladyngja – Iceland : IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 7-13 April. Lava from the third fissure flowed S into Geldingadalur and NE towards the Meradalir valley site. Flows from the three fissures connected into one flow field on 7 April. Another new fissure opened at around 0300 on 10 April, halfway between two existing fissures, and all four fissures were simultaneously active. Lava flowed towards Geldingadalur. Gas-rich emission plumes were visible in webcam images rising 1.1-1.3 km (3,600-4,300 ft) a.s.l. At least two new vents opened on 13 April based on webcam views. On 14 April IMO noted that lava was flowing from at least eight vents and unverified reports form the morning suggested two additional vents had opened. Sulfur dioxide gas flux was 29 kilograms per second, comparable to measurements collected during the previous few weeks.

IMO warned visitors that new fissures could open without adequate visible warning, especially in an area just S of Keilir, by Litla-Hrút, where seismicity was concentrated. They also warned of increased gas emissions hazards. The Aviation Color Code remained Orange due to the lack of ash and tephra emissions.

Pacaya – Guatemala : INSIVUMEH reported that the eruption at Pacaya’s Mackenney Crater continued during 7-13 April. Explosions during 6-7 April produced ash plumes that rose 1 km above the summit and drifted 10 km W and SW. Ballistics were ejected 50-150 m above the summit. Explosions during 8-9 and 11-12 April produced ash plumes that rose as high as 1 km and drifted as far as 10 km NE, W, and SW.

The lava flow on the W and SW flanks was 3.7 km long and continued to be fed. Incandescent lava blocks were spalled from the flow front and vegetation was set on fire. The lava advanced W onto the La Breña farm and SW towards El Patrocinio and El Rodeo, near the Campo Alegre farm. On 12 April the flows burned La Breña coffee and avocado plantations. By 13 April the lava flows were 3.8 km long, and within 370 m of houses in El Patrocinio. Another flow front was 250 m E of El Rodeo, and obstructed the road that connects El Rodeo, El Caracol, and Los Pocitos.

Piton de la Fournaise – Reunion Island (France) : OVPF reported that a seismic crisis at Piton de la Fournaise began at 1457 on 9 April and was accompanied by rapid deformation beneath the S flank. Seismicity indicated that a fissure opened at 1900 but could not be visually confirmed due to weather conditions. The Alert Level was raised to 2-2. During an overflight at 0840 on 10 April scientists observed a NNW-oriented fissure, 700 m S of Château Fort. Activity was focused at two vents, each producing lava fountains that were no higher than 30 m tall, though fountains also rose from other parts of the fissure. Slow-moving ‘a’a lava flowed SE and then curved E and advanced 1.6 km to 1,800 elevation. The N end of the fissure was no longer active. Two cones had formed over the main vents and were growing larger; by 11 April the more northern vent was the larger of the two. Fountains rose 30-60 m and the lava flow had advanced to 1,750 m elevation. By 1900 on 11 April the lava flow was 3.2 km long and had reached 1,690 m elevation. Lava fountaining continued at the two vents during 12-13 April, rising 20-60 m. The lava flow continued to advance; by 13 April the flow was about 3.6 km long and had reached 1,500-1,550 m elevation.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that low-level ash emissions from Semisopochnoi were visible in satellite images on 12 April along with a steam plume drifting E beyond the island. Additionally, new ash deposits extending SE at least to the coastline were also visible. The event was recorded by the regional infrasound network. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Soufriere St. Vincent – St. Vincent : University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the effusive eruption at Soufrière St. Vincent (often simply referred to as “La Soufriere”) became explosive on 9 April after a period of increased seismicity, gas emission, and rapid dome growth. Earthquake swarms were recorded during 22-25 March and 5 April, signifying a change in the eruption pattern. Small earthquakes associated with dome growth were recorded on 7 April. Episodes of tremor indicating movement of magma and fluids close to the surface began at 0300 on 8 April and were again recorded at 0530, 0800, 1015, and 1300, slowly increasing in magnitude. Five long-period earthquakes and two brief swarms of VT events occurred in between the tremor episodes; ash venting occurred with the last episode. Sulfur dioxide emissions were identified in satellite data, and clouds of steam and gas were visible from the Belmont Observatory. Later that evening, incandescent material over the vent area was visible in webcam images, and views from the observatory indicated that the dome had grown significantly. The Alert Level was raised to Red at around 1830, and the Prime Minister issued an evacuation order for the Red Zone at the N part of the island, affecting 16,000-20,000 people.

An explosive eruption began at 0840 on 9 April when an ash plume rose to 8 km (27,900 ft) a.s.l. and drifted mainly ENE. Ash fell across the island, affecting communities including Chateaubelair and Petite Bordel, the observatory, Belmont and surrounding areas at the S end of the island, and forcing the closure of the Argyle International Airport (20 km S). NEMO stated that evacuations in the Orange and Red zones were impeded by significant ashfall and poor visibility, but by the evening most residents had been evacuated. A second period of vigorous ash venting began at 1445 and initially rose about 4 km (13,100 ft) a.s.l. Lightning was visible in the rising plume. Successive explosions and ash pulses fed the plume for hours and it rose to 16 km (52,000 ft) a.s.l. A third explosive series began at 1835. Ash venting occurred through the night, causing ashfall across St. Vincent and reaching Barbados, about 165 km E, significantly impacting residents on that island.

Periods of banded tremor began at 0330 on 10 April, lasting for periods of 20-30 minutes with 1-3-hour gaps. The tremor episodes were associated with explosive activity and stronger pulses of ash emissions to higher altitudes; ash plumes rose to 10.6-16 km (35,000-52,000 ft) a.s.l. throughout the day. The Washington VAAC stated that ash plumes during 9-10 April had drifted as far as 1,200 km ESE and about 3,000 km ENE. The Grantley Adams International Airport (GAIA) in Barbados also closed.

Ashfall continued to be widespread on 10 April; deposit thickness varied from less than 1 mm in Colonaire (~12.5 km SSE) to 10-15 mm in Rabacca (~7.4 km SSE). Scientists reported darkness at the observatory at 1617; video showed intense and continuous ashfall. Satellite data confirmed that explosions had excavated the 2020-2021 lava dome and parts of the 1979 dome, leaving a large crater.

Overnight during 10-11 April ash again fell island-wide, and also in the Grenadines (to the SSW), Barbados, and Saint Lucia (50 km NNE). Explosions early on 11 April were followed by widespread power and water outages on the island as reported by NEMO, and some houses had collapsed under the significant ashfall. Beginning around midday the periods between episodes of high-amplitude tremor lengthened from 1.5-4 hours to 5-8 hours. The VAAC reported that through the day ash plumes rose 12.2-16 km (40,000-52,000 ft) a.s.l. and continued to drift long distances to the ENE, E, and SE. A large explosion at 0415 on 12 April produced an ash plume that rose to 12.8 km (42,000 ft) a.s.l. Pyroclastic flows descended several valleys on the S and W flanks, reaching the coast at Morne Ronde (4.3 km W), Larikai (3.5 km WNW), and Trois Loupes Bay (3.5 km NW). Damage to vegetation was extensive along the W coast, stretching from Larikai Bay to Turner Bay. The pattern of seismicity again changed; high-amplitude tremor episodes ceased, but two low-amplitude and one high-amplitude episode were recorded during 0600-1700. Explosivity or notable ash venting coincided with the episodes; the spacing between explosive events increased.

A series of Vulcanian explosions began at 0630 on 13 April and lasted about 30 minutes. The VAAC stated that a dense ash plume rose to 11 km (35,000 ft) a.s.l. and drifted E and SE, as well as N and NE. Pyroclastic flows traveled about 6 km WSW, reached the ocean at Wallibou Bay, and extended past the coastline over the sea. Scientists observed the western coastline later in the day and noted that pyroclastic flows had descended all valleys from Larikai (W) to Wallibou, a stretch about 5 km long. Lahar deposits were observed in the Sandy Bay area. The VAAC noted that at 1850 a new ash emission rose to 7.6 km (25,000 ft) a.s.l. and was associated with a thermal anomaly. UWI-SRC stated that a large explosion was recorded around 2300. Pyroclastic flows overnight were channeled to the E into the Rabacca River drainage. The Montserrat Volcano Observatory stated that a sulfur odor and minor ashfall from Soufrière St. Vincent was observed on their island (390 km NNW).

Daily satellite-based measurements of SO2 were notable beginning on 9 April. Though the initial explosion at 0840 showed relatively minor SO2 emissions, stronger, continuous ash and SO2 emissions began later on 9 April (at 1445) and continued into the next day, transitioning into discrete explosive events that continued a least through 14 April. Satellite data showed about 0.4 teragrams (Tg) of SO2 in the plume on 10 April, with some stratospheric injection. Simon Carn noted that this makes the La Soufriere eruption the largest tropical SO2 emission since the 2011 Nabro eruption, and the largest in the Caribbean since satellite measurements began in 1979. The SO2 plume initially fanned out to the NE, E, and SE across the Atlantic Ocean. Measurements during 11-13 April showed similar results of 0.4-0.6 Tg SO2 depending on altitude. The eastern edge of the gas plume reached about 4,700 km to the W coast of Africa by 12 April, and another 2,000 km inland to Mali and Niger on 13 April.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that incandescence from Suwanosejima’s Ontake Crater was visible at night during 5-9 April. Four explosions generated ash plumes that rose as high as 1.6 km above the crater rim and ejected bombs 600 m away. Ashfall was reported in Toshima village (4 km SSW) during 8-9 April. The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 31 March 2021 – 6 April 2021

Aira – Kyushu (Japan) : JMA reported that during 29-30 March explosions at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) produced ash plumes that rose as high as 2.7 km above the crater rim and ejected bombs 600-900 m away. An explosion was recorded on 4 April. An explosion at 0641 on 5 April ejected bombs 800-1,100 m away from the crater and generated an ash plume that rose up to 3 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 31 March-6 April ash plumes from Dukono rose to 2.4 km (8,000 ft) a.s.l. and drifted E, SE, and SSE. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 25 and 28-29 March that sent ash plumes up to 2.5 km a.s.l. (8,200 ft) and drifted in different directions. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Etna – Sicily (Italy) : INGV reported continuing episodes of lava fountaining, intra-crater explosive activity, and discontinuous ash emissions at Etna’s Southeast Crater (SEC) during the week of 29 March-4 April, though weather conditions often prevented visual observations. Gas emissions rose from the other summit craters and occasional explosive activity was visible; puffs of ash sometimes rose from Voragine Crater during 31 March-2 April. At 0707 on 31 March a loud explosion was followed by several ash puffs, marking the beginning of the 17th lava-fountaining episode since they began on 16 February. At around 1100 a thermal anomaly at the S base of SEC was visible during an overflight and in thermal camera images. Explosive activity increased by late afternoon and several lava flows effused from the S-base vent. The main part of the flow traveled towards the Valle del Bove with other smaller flows traveled S and SW. Two other vents at the S base had opened by evening and one ejected spatter a few tens of meters high. Periods of lava fountaining began through the night, and the main lava flow descended the W wall of the Valle del Bove. Strombolian activity intensified at 1950, with an eruption plume that rose to 1.2 km (4,000 ft) a.s.l. and drifted SSW. Lava fountaining began at around 0100 on 1 April. At 0218 lava overflowed the E rim of SEC and headed towards the Valle del Bove, running parallel to the flows from the S base. Lava fountains continued to be visible during the morning of 1 April and intense Strombolian activity produced dense ash plumes that drifted S. By 0940 the eruption plume had risen to 9 km (29,500 ft) a.s.l. and drifted SSW. Lava fountaining ceased around 1000 and the eruption plume rose to 5.5 km (18,000 ft) a.s.l. and drifted S. Ash fell in Milia, Nicolosi, and Catania and lapilli (1 cm in diameter) fell in Rifugio Sapienza. Lava effusion and flow advancement continued; lava from the S base of SEC spread out like a fan. A series of loud bangs were audible in the late morning and ash emissions continued until the afternoon. Lava overflowed the E rim of SEC at 1040, and a SSE flow entered the Valle del Bove at the SW wall. Explosive activity began to decline at 1320, and effusive activity waned overnight during 1-2 April.

Gareloi – United States : AVO reported that a loss of operation and communication with all seismic stations on Gareloi was likely due to snow cover. Both the Aviation colour Code and the Volcano Alert Level were changed to Unassigned, reflecting the lack of this data to detect unrest. The observatory noted that regional infrasound networks, lightning detection, and satellite images will be used to monitor and detected unrest.

Kilauea – Hawaiian Islands (USA) : HVO reported that the W vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 31 March-6 April. Lava flowed at a low rate from the main vent into the lake through crusted-over channels and submerged inlets. The total depth of the lake measured about 225 m and lava continued to circulate in the W part; the E half of the lake remained solidified and expanded toward the W. The sulfur dioxide emission rate was 1,200 tons/day on 1 April. HVO field crews observed weak spattering from two areas at the W vent during 1-2 April. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Langila – New Britain (Papua New Guinea) : Based on analyses of satellite imagery and wind model data, the Darwin VAAC reported that on 5 April an ash plume from Langila rose to 1.5 km (5,000 ft) a.s.l. and drifted SW.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 30 March-6 April. Gray-and-white ash plumes rose as high as 700 m above the summit and drifted in multiple directions, though rainy weather conditions prevented visual observations during 2-3 and 5 April. Incandescent material was ejected 300-500 m above the summit and 500 m SE during 30-31 March; eruptive events were recorded by the seismic network on the other days but not visually confirmed. Rumbling was occasionally noted. According to news articles secondary lahars from Cyclone Seroja destroyed homes, and impacted as many as 300, in several villages to the SW; mud-and-debris flows and flooding severely impacted other parts of Indonesia and killed at least 70 people. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 4 km away from the summit crater.

Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both continued to grow during 26 March-1 April. The SW rim lava-dome volume was an estimated 1,060,000 cubic meters on 1 April, with a growth rate of about 13,400 cubic meters per day, and continued to shed material down the flank. A total of 14 pyroclastic flows traveled a maximum of 1.8 km down the SW flank. Incandescent avalanches, recorded 158 times, traveled as far as 1.1 km down the SW flank. The summit lava dome had grown to 70 m tall and produced one incandescent avalanche. Minor ashfall was reported in Ngadirojo, Stabelan (4 km NW), Takeran, Tlogolele (5 km NW), Selo (3 km NNW), Pos Babadan (4 km NW), and Pasar Talun (12 km W). The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the summit.

Raung – Eastern Java (Indonesia) : PVMBG reported that daily gray-and-white ash plumes rose 50-500 m above Raung’s summit during 31 March-5 April and drifted N and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 28 March-2 April. On 3 April a plume of re-suspended ash rose to 2.5 km (8,200 ft) a.sl. and drifted 250 km ESE. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Shishaldin – Fox Islands (USA) AVO reinstated the Green Aviation colour Code and the Normal Volcano Alert Level for Shishaldin on 2 April, after several seismic stations again became operational following a months-long outage, thus improving the observatory’s monitoring capability.

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 31 March-6 April. Weather conditions sometimes prevented visual observations of the volcano, though daily white fumarolic plumes were visible rising as high as 500 m above the summit. Avalanches were detected daily by the seismic network and observed traveling 500-1,500 m down the E and SE flanks. An eruptive event produced a gray ash plume that rose 500 m above them summit on 1 April. Pyroclastic flows went as far as 1.5 km down the E and SE flanks. Ash plumes rose 0.7-2 km during 2-5 April and mainly drifted E and SE. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Soufriere St. Vincent – St. Vincent : University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the lava dome in Soufrière St. Vincent’s main crater continued to slowly grow during 31 March-6 April, expanding to the N and S. Gas-and-steam continued to rise from the top of the dome, as well as along the contact with the pre-existing 1979 dome. A swarm of volcano-tectonic (VT) earthquakes began at 0638 on 5 April. The number and frequency of the VTs increased until about 0830 and then stabilized. The rate declined at around 1400 and then significantly dropped at 1600, though small VT events continued to be detected through 1800. The events were located at depths of 6 km, slightly deeper than the swarm events recorded during 22-25 March, located at revised depths of 3-5 km. Several reports of felt events came from nearby communities, including Fancy and Chateaubelair. The largest event, a M 3.5, was recorded at 0920 and felt by local residents. The swarm was more intense than the previous one, with an average rate of about 50 earthquakes per hour compared with 1.5 per hour during 22-25 March. The Alert Level remained at Orange (the second highest level on a four-colour scale).

Tanaga – Andreanof Islands (USA) : AVO reported a loss of operation and communication with all but two seismic stations on Tanaga, likely caused by snow cover. Both the Aviation colour Code and the Volcano Alert Level were changed to Unassigned, reflecting the inability to locate earthquakes to detect unrest. Monitoring will continue with the remaining seismic stations, regional infrasound networks, lightning detection, and satellite images.

Tengger Caldera – Eastern Java (Indonesia) : PVMBG reported that during 30 March-5 April white steam-and-gas plumes rose 50-700 m above the summit of Tengger Caldera’s Bromo cone. The plumes were white to gray during 1-2 April. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to stay outside of a 1-km radius of the crater.

Ubinas – Peru : Instituto Geofísico del Perú (IGP) reported that during 29 March-4 April there were 11 volcano-tectonic earthquakes at Ubinas with magnitudes less than 1.8, and a few seismic signals indicated emissions. Sporadic steam-and-gas plumes rose as high as 200 m above the crater rim. On 5 April the Alert Level was lowered to Green (the lowest level on a four-colour scale).

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 31 March 2021 – 6 April 2021

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that explosions at 1130 on 3 April likely caused ash plumes to rise to 8.5 km (27,900 ft) a.s.l. above Karymsky and drift NE, based on satellite data. The Aviation colour Code was raised to Orange (the second highest level on a four-colour scale).

Krysuvik-Trolladyngja – Iceland : IMO reported that the small eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 31 March-6 April. Video and visitor photographs showed spattering and lava fountaining from the two cones, and lava flows from both cones moved W and S within the Geldingadalur valley. A new fissure, 100-200 m long, opened about 700 m NE of the Geldingadalur cones around noon on 5 April. During a helicopter overflight, scientists observed a gas plume rising from the new fissure and a fast-moving lava flow descending into the Meradalir valley to the SE. On 6 April lava from the second fissure was advancing at a rate of 7 cubic meters per second; lava-flow rates at the Geldingadalir site averaged 5.5 cubic meters per second. Around midnight during 6-7 April a third fissure opened in between the first two; all three were oriented NE-SW. Earlier on 6 April field teams had observed a landslide in same area. Lava from the third fissure mostly flowed SW into Geldingadalur. The Aviation colour Code remained Orange due to the lack of ash and tephra emissions.

Pacaya – Guatemala : INSIVUMEH reported that explosions at Pacaya’s Mackenney Crater during 30-31 March produced gas-and-ash plumes that rose 1.8 km above the summit and drifted up to 50 km S, SW, W, and NW. Explosions ejected blocks as high as 150 m above the summit. Lava flows on the W flank advanced to 3 km long and were near La Breña; the flows overtook an unoccupied building on the Campo Alegre farm that was used for monitoring and visitor services. The flow front was about 500 m from the town of El Patrocinio. Incandescent blocks detached from the end of the lava flow and set fire to vegetation. During 31 March-2 April explosions ejected incandescent blocks as high as 225 m above the summit. Ash plumes rose 500 m and drifted 20 km S and SW. The SW-flank lava flows remained active. Explosions continued during 3-6 April, with ash plumes rising as high as 1 km and drifting 6-20 km W, SW, and S. The lava flow continued to be active on the SW flank, setting fire to local vegetation. Strombolian activity ejected material 300 m high during 5-6 April.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that a small plume from Semisopochnoi’s North Cerberus crater was visible in a satellite image on 31 March. Steam obscured the crater during the first part of 1 April. Later that day an ash plume was visible, and was followed by a sulfur dioxide plume an hour later. At 2200 a plume rose to an altitude below 3 km (10,000 ft) a.s.l. No activity was identified in partly cloudy images during 2-6 April. The Aviation colour Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that during 30-31 March large volcanic bombs were ejected at least 41 times from Suwanosejima’s Ontake Crater as high as 800 m above the crater rim and to distances as far as 1 km. The Alert Level was raised to 3 (on a 5-level scale) at 0330 on 31 March and the public was warned to stay outside a 2 km radius of the crater. The increased activity prompted an overflight that same day where scientists confirmed several hundred high-temperature bomb deposits with a thermal camera within a 1 km radius. Explosions at 2205 on 30 March and 0257 on 31 March ejected bombs onto the S and SE flanks, respectively. Grayish-white emissions rose from the crater. After 1500 eruption plumes rose as high as 1.4 km above the crater rim. The number of explosions decreased; two per day were recorded during 1-2 April and one was recorded on 3 April. The Alert Level was lowered to 2 on 5 April and the public was warned to stay 1 km away from the crater.

Veniaminof – United States : AVO reported that during 31 March-1 April clear satellite and web camera images of Veniaminof showed no signs of emissions. On 2 April the Volcano Alert Level was lowered to Advisory and the Aviation colour Code was lowered to Yellow. Satellite data showed elevated surface temperatures, especially over the flank-vent lava flows through 4 April. Low-level ash emissions were recorded by the webcam on 5 April, prompting AVO to raise the Volcano Alert Level and Aviation colour Code to Watch and Orange, respectively. Tephra deposits were visible to the SE.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 24 March 2021 – 30 March 2021

Aira – Kyushu (Japan) : JMA reported that during 22-26 March incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. An explosion on 25 March produced an eruption plume that rose 1.4 km above the crater rim. On 27 March at 0236 an eruption generated an ash plume that rose 2.5-4 km above the crater rim and drifted NW, resulting in a large amount of ashfall in Kagoshima City (about 10 km W). Volcanic bombs were ejected 1-1.3 km away from the crater. An eruption on 29 March at 1557 produced an eruption plume that rose 2.2 km above the crater rim and drifted SE, resulting in a pyroclastic flow down the SE flank and ashfall in Kagoshima City and the Kagoshima Prefecture. An explosion on 30 March at 0433 generated an ash plume that rose 2.7 km above the crater and drifted E, ejecting bombs 600-900 m from the crater. Ashfall was again reported in Kagoshima City. The Alert Level remained at 3 (on a 5-level scale).

Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 24-30 March ash plumes from Dukono rose to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted in multiple directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 19, 21, and 24-25 March that sent ash plumes up to 2.5 km a.s.l. (8,200 ft) and drifted in different directions. Ashfall was reported in Severo-Kurilsk on 24 March. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Fuego – Guatemala : INSIVUMEH reported that 6-11 explosions per hour were recorded during 24-30 March at Fuego, generating ash plumes that rose to 4.7 km (15,000 ft) a.s.l. and drifted W, NW, and SW as far as 10-15 km. Shock waves rattled buildings near the volcano. Block avalanches descended the Seca (W), Ceniza (SSW), and Trinidad (S) drainages, often reaching vegetated areas. Ash plumes from explosions rose to 4.8 (16,000 ft) km a.s.l. and drifted N and NE on 25 March and W on 27 March far as 15-20 km, resulting in ashfall in Morelia (9 km SW), Panimache (8 km SW), Yucales (12 km SW), Sangre de Cristo (8 km WSW), Yepocapa (8 km NW), La Soledad (11 km N). Block avalanches descended the Taniluyá (SW), Las Lajas (SE), and Honda drainages, in addition to those affected on 24 March. Weak crater incandescence was observed at night and in the early morning during 26 March. Incandescent material was ejected 100-200 m above the summit on 28 March, accompanied by ash plumes that rose to 4.8 km a.s.l. and resulted in ashfall in Palo Verde, Panimaché II, Sangre de Cristo, Yepocapa, and El Porvenir (8 km ENE).

Ibu – Halmahera (Indonesia) : PVMBG reported that on 25 March at 1814 a gray ash plume from Ibu rose to 2.3 km (7,500 ft) a.s.l. and drifted W. White-and-gray emissions rose 200-1,000 m above the crater drifting N, S, E, and W during 25-26, 28, and 30 March. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater and 3.5 km away on the N side.

Kilauea – Hawaiian Islands (USA) : HVO reported that the W vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 24-30 March. Lava flowed from the main vent into the lake through two crusted-over channels and submerged inlets, the former of which occurred during 24-25 March. The total depth of the lake measured about 224 m and lava continued to circulate in the W part; the E half of the lake remained solidified, expanding toward the W. The sulfur dioxide emission rate was 950 and 650 tons/day on 22 and 26 March, respectively. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Klyuchevskoy – Central Kamchatka (Russia) : KVERT reported that the flank eruption on Klyuchevskoy’s lower NW flank had ended on 20 March. Weak incandescence from the cinder cone and lava flows visible in webcam images reflected cooling. The temperature of the thermal anomaly identified in satellite data continued to decrease. On 24 March the Aviation colour Code was lowered to Green (the lowest level). According to satellite data, a plume of resuspended ash extended for 72 km E of the volcano on 25 March; no eruption was reported. On 25 March the Aviation colour Code was briefly increased to Orange (the second highest level on a four-colour scale) and was lowered to Green by 26 March.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 24-30 March. Daily gray-and-white ash plumes rose as high as 800 m above the summit and drifted in different directions. Incandescent material was ejected 500 m above the summit on 23, 27, and 30 March, and 300 m above the summit on 25 March. On 26 and 28 March incandescence was observed up to 100 m above the summit, accompanied by incandescent ejecta as far as 350 m to the SE. The eruptive events were accompanied by rumbling and banging sounds. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim continued to grow and shed material down the flank during 19-25 March. The 2021 lava dome volume was an estimated 949,000 cubic meters on 25 March, with a growth rate of about 13,300 cubic meters per day. The Mount Merapi Selo Observation Post reported a white gas-and-steam plume rose 500 m above the crater on 25 March at 1430. Four pyroclastic flows traveled a maximum of 1.8 km down the SW flank, three of which occurred on 27 March at 0602, 0603, and 0631. An ash plume caused by a pyroclastic flow rose 3.5 km (12,000 ft) a.s.l. and drifted SW for about 1.3 km on 27 March at 1758 on, according to a ground observer. Incandescent avalanches, recorded 104 times, traveled as far as 1.2 km down the SW flank and twice down the SE flank as far as 400 m. The summit lava dome measured 65 m tall, similar to the previous week. On 30 March there were 33 incandescent avalanches observed traveling up to 1 km down the SW flank, one of which continued up to 1.5 km. One incandescent avalanche was observed from the lava dome. The Alert Level remained at 3 (on a scale of 1-4), and the public were warned to stay 5 km away from the summit.

Raung – Eastern Java (Indonesia) : PVMBG reported that daily gray-and-white ash plumes rose 50-1,200 m above Raung’s summit during 24-29 March. Ash plumes drifted in different directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Reventador – Ecuador : IG reported that a high level of activity continued to be recorded at Reventador during 24-30 March; adverse weather conditions sometimes prevented visual confirmation. Seismicity was characterized by 49-80 daily explosions, volcano-tectonic and harmonic tremor events, and long-period earthquakes, as well as signals indicating emissions. Gas, steam, and ash plumes, often observed multiple times a day with the webcam or reported by the Washington VAAC, rose as high as 1.4 km above the summit crater and drifted mainly W, NW, SW. Crater incandescence and incandescent blocks rolling down the NE flank were observed nightly and accompanying explosions during 24-25 March.

Sabancaya – Peru : Instituto Geofísico del Perú (IGP) reported a daily average of 90 explosions at Sabancaya during 22-28 March. Gas-and-ash plumes rose as high as 2.5 km above the summit and drifted SW, W, N, and NW. Six thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. Minor inflation continued to be detected in areas N of Hualca Hualca (4 km N). The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 12-km radius.

Sangay – Ecuador : IG reported a high level of activity at Sangay during 24-30 March. Seismicity was characterized by 1-8 daily explosions, long-period earthquakes, and signals indicating emissions. Weather clouds and rain often prevented visual observations of the volcano, though based on the Washington VAAC reports, daily ash plumes were noted rising as high as 2.1 km above the summit and drifting in different directions. Images shared by the Red de Observadores Volcánicos (ROVE) (Network of Volcanic Observers) showed gas-and-steam emissions reaching 900-1,000 m above the crater drifting N on 26-27 March. A seismic station recorded occasional debris flows during 24-30 March. No ashfall was reported by residents.

Santa Maria – Guatemala : INSIVUMEH reported that during 24-30 March weak explosions at Santa María’s Santiaguito lava-dome complex generate ash plumes that rose to 2.8-3.4 km (9,000 ft-11,000 ft) a.s.l. and drifted W, NE, SW. Collapses of blocky lava from the Caliente dome sent avalanches on the S and SW flank of the Caliente dome, causing minor ashfall around the volcano. Block avalanches were also observed on the E and S flanks; ashfall was reported in San Marcos (8 km SW) and Loma Linda Palajunoj (6 km WSW) on 25 and 27 March. Minor pyroclastic flows were reported on 28 March.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that lava dome growth at Sheveluch continued during 20-26 March, accompanied by strong fumarolic activity, incandescence, and block avalanches. Satellite imagery showed a thermal anomaly over the lava dome all week, except on 22 and 25 March due to cloud cover. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 24-30 March. The Darwin VAAC reported that an eruption on 28 March generated an ash plume that rose to 3.4 km a.s.l. (11,000 ft). Explosions on 29 March at 0024 and 1035 produced ash plumes that rose to 3.5 km a.s.l. (11,500 ft) and drifted NNE and ESE, respectively. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Soufriere St. Vincent – St. Vincent : University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the lava dome in Soufrière St. Vincent’s main crater continued to slowly grow during 23-27 March, expanding to the N and S. Gas-and-steam continued to rise from the top of the dome, as well as along the contact with the pre-existing 1979 dome. On 23 March at 1030 the monitoring network recorded a swarm of small low-frequency seismic events that lasted about 45 minutes, which was likely associated with magma movement beneath the dome. Starting at 1653 the monitoring network also began to detect volcano-tectonic (VT) earthquakes, some of which have been felt by nearby communities, including Fancy, Owia, and Sandy Bay. On 26 March the period of elevated VT earthquakes stopped; only small, low frequency events associated with the growth of the lava dome were recorded. The Alert Level remained at Orange (the second highest level on a four-colour scale).

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that the seismic network for Suwanosejima’s Ontake Crater detected a total of 17 explosions during 19-26 March. These events produced eruption plumes that rose as high as 1.2 km above the crater rim, drifting S, W, and SW, and ejected bombs as far as 500 m away from the crater. Incandescence from the crater was occasionally visible at night. On 30 March at least 18 explosions were detected, generating ash plumes that rose 600-1,500 m above the crater drifting E, SE, and NE and ejecting material as far as 800 m S of the crater. On 31 March the Alert Level was raised to 3 (on a 5-level scale).

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 24 March 2021 – 30 March 2021

Cleveland – Chuginadak Island (USA) : AVO reported that a magnitude 4.3 earthquake at Cleveland was recorded during the morning of 26 March. Smaller earthquakes continued to be detected that day at a decreasing rate. There have been no signs of activity observed in infrasound or satellite data, nor evidence of volcanic gas emissions and elevated surface temperatures due to clouds. The Aviation colour Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Etna – Sicily (Italy) : INGV reported continuing episodes of lava fountaining at Etna’s Southeast Crater (SEC) during the week of 22-28 March, though weather conditions often prevented visual observations. Weak Strombolian activity at SEC began at 2005 on 23 March and turned into lava fountaining at 0330 on 24 March. A lava flow from the SEC was observed at 0335 which split in two, one branch traveling toward the Valle del Bove and the other to the SE; the lava was followed by a pyroclastic flow at 0336 that traveled toward the Valle del Bove. The lava fountain produced an ash cloud that rose to 6-7 km (20,000-23,000 ft) a.s.l. and extended SSE, resulting in ashfall on the S slope and in Catania (29 km SSE). Lava fountaining gradually decreased at 0700, and by 0945 it had stopped. The lava flows continued to advance. Activity in Northeast (NEC), Bocca Nuova (BN), and Voragine (VOR) was characterized by variable intra-crater Strombolian activity, accompanied by sporadic and weak ash emissions that quickly dispersed. On 24 March explosions at SEC continued after the lava fountaining had stopped, producing an ash plume that rose 4.5 km (15,000 ft) a.s.l. and drifted SE. At night, ashfall was reported in Milia and Trecastagni (16 km SE). Explosions stopped by 1347 that day. By 25 March the two active lava flows had ceased and began to cool. Weak Strombolian activity at SEC on 30 March resumed around 2030; intra-crater explosions continued in the NEC, BN, and VOR, the latter of which produced discontinuous ash emissions that rapidly dispersed in the summit area.

Krysuvik-Trolladyngja – Iceland : IMO reported that the small eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula continued during 24-30 March. Video and visitor photographs showed that continuous spattering and lava fountaining resulted in the formation of a second large cone adjacent to the main cone. Lava flows from both cones moved W and S within Geldingadalur valley. On 25 and 29 March the extrusion rate from the cone was an estimated 5.8 and 5.3 cubic meters per second, respectively, based on the latest Pléiades image acquisition (LMI). A gas plume on 25 and 29 March rose to 1 km (3,300 ft) a.s.l; no ash or tephra was produced. Minor seismicity continued around the Fagradalsfjall area. Video data showed that on the morning of 28 March the N part of the largest cone along the fissure collapsed. Sulfur dioxide flux was 18-19 kg/s and drifted predominantly S. The IMO periodically issued warnings about weather conditions that would cause high concentrations of volcanic gases to settle near the eruption site, causing hazardous conditions for visitors. The Aviation colour Code remained Orange due to the lack of ash and tephra emissions.

Pacaya – Guatemala : INSIVUMEH reported moderate to s trong explosions at Pacaya’s Mackenney Crater during 24-30 March, accompanied by abundant ash plumes that rose to 2.9-4.5 km (9,500-13,000 ft) a.s.l. and drifted in multiple directions as far as 15-20 km. Resulting ashfall was reported in El Pepinal (7 km N), San Francisco de Sales (5 km N), El Cedro (9 km NNW), Calderas (3 km N), Mesías Altas, Mesías Baja (5 km NE), El Rodeo (4 km WSW), El Patrocinio (5 km W), and San Vicente Pacaya (5 km NW). The lava flow that began on 18 March was 2.5 km long, continuing down the SW flank; the height of the flow was 2.5 m with a width of 400 m, but the advancing front was 250 wide and set fire to nearby vegetation. Incandescent material ejected 150-300 m above the rim fell around the crater on 25 and 27 March. On 30 March ash plumes drifted 7 km S, causing ashfall in El Chupadero (2-2.5 km S) and Los Pocitos (5.5 km S).

Pelee – Martinique (France) : L’Observatoire Volcanologique et Sismologique de Martinique (OVSM) reported that seismicity at Pelée increased during 19-26 March. The seismic network recorded at least 55 high-frequency volcano-tectonic earthquakes with magnitudes less than or equal to 1, located at depths between 1.7 km below sea level and 1 km above sea level. The Alert Level remained at Yellow (the second lowest level on a four-colour scale).

Piton de la Fournaise – Reunion Island (France) : OVPF reported that seismicity remained elevated at Piton de la Fournaise during 22-26 March. On 24 March there were 81 earthquakes recorded under the summit, accompanied by deformation and 31 collapses along the edges of the Dolomieu Crater. Inflation centered 1.5 and 2 km below the crater continued through the week. On 26 March up to 95 summit volcano-tectonic earthquakes were recorded; the daily number of earthquakes then decreased, with 55 on 27 March and 8 on 28 March.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that satellite data showed minor ash deposits on Semisopochnoi’s flanks. Three explosions on 25 March (at 0142, 0330, and 0645) were recorded by regional infrasound sensors. Two more explosions were detected at 2130 on 26 March and at 0030 on 27 March; high weather cloud cover at 9.1 km (30,000 ft) a.s.l. prevented satellite confirmation; no ash was visible above the cloud deck during 25-27 March. The Aviation colour Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Taal – Luzon (Philippines) : PHIVOLCS reported that seismicity increased at Taal during 24-27 March. There were around 19-302 volcanic earthquakes recorded daily, except on 28 March, and about 4-243 periods of volcanic tremor with variable durations (1-24 minutes). Four hybrid earthquakes were recorded on 24 March. Low-frequency earthquakes were detected 25, 77, 118, 7, and 16 times on 25, 26, 27, 28, and 30 March, respectively. Diffuse steam plumes from fumarolic vents in the Main Crater rose as high as 40 m. Daily measurements of sulfur dioxide emissions were 837-1,109 tonnes/day. The Alert Level for Taal remained at 2 (on a scale of 0-5). PHIVOLCS strongly recommended no entry onto the island, and access to the Main Crater and Daang Kastila fissure (along the walking trail) was strictly prohibited.

Veniaminof – United States : AVO reported that eruptive activity at Veniaminof continued during 24-25 and 27-30 March. Highly elevated surface temperatures were visible in satellite images along with ash deposits that were primarily confined to the summit and upper flanks on 23 March. Low-level tremor was recorded in local seismic data. During 24 March explosions were recorded in local seismic data and in infrasound data sensors; frequent explosive booming (several per minute) was reported by residents in Perryville (35 km SE) and Chignik Lagoon (55 km NE). Cloud cover prevented visual confirmation during this period of increased seismicity. Fresh ash deposits extending 10 km SE in the summit caldera were observed in satellite data on 25 March. Satellite data also showed highly elevated surface temperatures at the summit and flank vent during clear weather days on 25, 28, and 29 March. Discrete, short-lived ash emissions were detected during the afternoon and evening of 27 March in images from the FAA webcam in Perryville. The intermittent events lasted several minutes and produced small ash clouds that rose less than 300 m (1,000 ft) above the vent and drifted SE, which may have resulted in trace ashfall in Perryville, though there was no confirmed evidence. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 17 March 2021 – 23 March 2021

Aira – Kyushu (Japan) : JMA reported that during 15-22 March incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. An explosion on 15 March produced an eruption plume that rose 1.5 km above the crater rim and ejected bombs 500-700 m away from the crater. The explosions on 20 March generated plumes that rose as high as 1.6 km. The sulfur dioxide emission rate was 1,800 tons per day on 12 March. The Alert Level remained at 3 (on a 5-level scale).

Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 16-23 March ash plumes from Dukono rose to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted in multiple directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 12-15 and 18-19 March that sent ash plumes to 2.6 km (8,500 ft) a.s.l. and drifted E, NE, and NW. Ashfall was reported in Severo-Kurilsk on 12 March. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kilauea – Hawaiian Islands (USA) : HVO reported that two vents on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 17-23 March. Lava flowed from both the main vent and a vent several meters NE into the lake through submerged inlets. Another lava flow emerged from about halfway up the cone structure starting at 0220 on 16 March, but had ended by the next day. The depth of the western part of the lake rose from about 221 m to 223 m and lava continued to circulate in that part. The E half of the lake remained solidified and lower that the W half, with the crusted E half expanding towards the W. The sulfur dioxide emission rate was 650, 700, and 1,100 tons/day on 17, 18, and 19 March, respectively. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Klyuchevskoy – Central Kamchatka (Russia) : KVERT reported that the Strombolian eruption from vents on Klyuchevskoy’s lower NW flank continued during 12-19 March. A large, bright thermal anomaly over the vents was identified in satellite images. Kamchatka Volcanological Station scientists visited the eruption site on 16 March and observed decreased activity. A small lava flow effused from a vent at the W base of the cone and lava flowed from the N side. Every few seconds material was ejected as high as 100 m above the cone’s rim. On 22 March the cinder cone was weakly incandescent and lava effusion continued to be observed in webcam images. The temperature of the thermal anomaly identified in satellite data also significantly decreased. The Aviation colour Code was lowered to Yellow (the second lowest level on a four-colour scale) on 22 March. Two days later, on 24 March, the Aviation colour Code was lowered to Green (the lowest level); weak incandescence from the cone and flows visible in webcam images reflected cooling.

Laguna del Maule – Central Chile-Argentina border : SERNAGEOMIN reported that during 1-15 March the seismic network at Laguna del Maule recorded a total of 123 volcano-tectonic earthquakes. The largest event was a local M 2.4 located 8.2 km WSW of the lake, at a depth of 4.4 km. One tremor event was also recorded. Recent carbon dioxide emission measurements showed an upward trend and that the area of anomalous emissions had expanded. Deformation rates were higher than maximum averages. The Alert Level remained at Yellow, the second lowest level on a four-colour scale. ONEMI maintained a Yellow Alert for San Clemente and recommended restricted access within a radius of 2 km from the center of elevated carbon dioxide emissions.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 17-23 March. Daily gray-and-white ash plumes rose as high as 700 m above the summit and drifted mainly E and SE. Incandescent material was ejected 300 m E of the summit on 20 March. The next day incandescent material was ejected 100 m above the summit and as far as 200 m E. On 22 March explosions ejected incandescent material 250-350 m SE. The eruptive events were accompanied by rumbling and banging sounds. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 4 km away from the summit crater.

Nevados de Chillan – Chile : SERNAGEOMIN reported that activity at Nevados de Chillán’s Nicanor Crater was ongoing with sporadic gas-and-ash emissions and continuing lava effusion during 1-15 March. Explosions produced eruption plumes that rose as high as 1.3 km above the crater rim, and sometimes ejected material as far as 160 m onto the NE flank. The L5 lava flow on the N flank was about 925 m long and 80 m wide at the distal end, and continued to slowly advance. The Alert Level remained at Yellow, the second lowest level on a four-colour scale. ONEMI stated that Alert Level Yellow (the middle level on a three-colour scale) remained in place for the communities of Pinto and Coihueco, noting that the public should stay at least 2 km away from the crater.

Raung – Eastern Java (Indonesia) : PVMBG reported that daily gray-and-white ash plumes rose 300-900 m above Raung’s summit during 16-23 March. Ash plumes drifted mainly N, E, and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Reventador – Ecuador : IG reported that a high level of activity continued to be recorded at Reventador during 16-23 March; adverse weather conditions sometimes prevented visual confirmation. Seismicity was characterized by 31-81 daily explosions, volcano-tectonic and harmonic tremor events, and long-period earthquakes as well as signals indicating emissions. Gas, steam, and ash plumes were often observed multiple times a day with the webcam or reported by the Washington VAAC; they rose as high as 1.5 km above the summit crater and drifted mainly NE, E, and SW. Crater incandescence and incandescent blocks rolling at least down the N, NE, and E flanks were observed nightly.

Sangay – Ecuador : IG reported a high level of activity at Sangay during 17-23 March. Seismicity was characterized by daily explosions, long-period earthquakes, and signals indicating emissions. Weather clouds and rain often prevented visual observations of the volcano, though based on the Washington VAAC, webcam images, and observer reports, ash plumes were noted most days rising as high as 1.5 km above the summit and drifting mainly N, W, and SW. A seismic station recorded occasional debris flows during 17-19 March. No ashfall was reported by residents.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 12-19 March. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 16-23 March. Weather conditions often prevented visual observations of the volcano, particularly during the end of the week. Avalanches were detected daily by the seismic network and observed traveling 500-1,500 m down the E and SE flanks during 16-18 March. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Soufriere St. Vincent – St. Vincent : University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the lava dome in Soufrière St. Vincent’s main crater continued to slowly grow during 17-23 March, expanding to the N and S. A team visited the dome on 19 and 23 March to make observations, take measurements, and maintain monitoring equipment. Gas-and-steam continued to rise from the top of the dome as well as along the contact between the old and new domes. As of 19 March the dome was 105 m tall, 912 m long, 243 m wide, and had an estimated volume of 13.13 million cubic meters. The Alert Level remained at Orange (the second highest level on a four-colour scale).

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that the seismic network for Suwanosejima’s Ontake Crater detected a total of 11 explosions during 12-19 March. These events produced eruption plumes that rose as high as 1.7 km above the crater rim and ejected bombs up to 700 m away from the crater. Incandescence from the crater was occasionally visible at night. The Alert Level remained at 2 (on a 5-level scale).