Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 8 September – 14 September 2021

Aira – Kyushu (Japan) : JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 6-10 September. Deformation data showed inflation beginning at around 0300 on 13 September.

Cerro Hudson – Chile : SERNAGEOMIN lowered the Alert Level for Cerro Hudson to Green (the lowest level on a four-color scale) on 7 September, based on decreased activity. Neither morphological changes nor thermal anomalies were visible in satellite images or webcam views during 16-31 August. Seismicity remained low and sulfur dioxide emissions were not recorded.

Ebeko – Paramushir Island (Russia) : According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 4 and 6-8 September produced ash plumes that rose as high as 2 km (6,600 ft) a.s.l. and drifted N, S, and E. Ash fell in Severo-Kurilsk on 6 and 8 September.

Great Sitkin – Andreanof Islands (USA) : AVO reported that lava effusion continued at Great Sitkin during 7-14 September, though weather clouds often prevented webcam and satellite views. Seismicity remained elevated and was characterized by small earthquakes consistent with lava effusion. A radar image from 9 September indicated that the lava dome had grown to 1,100 m E to W and 860 m N to S, and was 25-30 m thick. Lava began to advance though a gap in the S rim of the summit crater. Elevated surface temperatures were visible in satellite data on 14 September.

Grimsvotn – Iceland : Icelandic Meteorological Office (IMO) reported that the jökulhlaup from the eastern and western parts of Grímsvötn’s caldera that began on 1 September had decreased during 8-10 September. IMO warned of continuing flood conditions in the downstream parts of the Skaftá river.

Ibu – Halmahera (Indonesia) : PVMBG reported that during 7-12 September gray-and-white ash plumes from Ibu rose 200-800 m above the summit and drifted N and W.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was identified in satellite images during 3-10 September. Ash plumes rose 4 km (13,100 ft) a.s.l. and drifted 165 km E during 2-6 and 9 September.

Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, had paused for several days. The Institute of Earth Sciences reported that based on aerial photography acquired on 9 September, during the pause, the area of the flow field had grown to 4.6 square kilometers, and the total volume erupted was 143 million cubic meters. The crater floor was visible and was at least 70 m deep, with a deeper cavity or drainage sometimes visible. Lava visibly returned on 11 September; RSAM values increased and low lava fountains emerged from a few areas on the flow field to the W of the main crater. Lava also returned to the main vent. Lava fountains from the main crater were visible for periods of 5-10 minutes on 13 September and lava advanced in multiple directions. Lava flowed N on 14 September. By 15 September lava quickly advanced S, flowing past the earthen barriers constructed at the S end of Geldingadalur valley, and turning E into the Nàtthagi valley. The Aviation Color Code remained at Orange due to the lack of ash and tephra emissions, though IMO warned of the potential for lapilli and scoria fallout within a 650 m radius of the active vent. Authorities also warned of gas emission hazards.

Langila – New Britain (Papua New Guinea) : Based on analyses of satellite imagery and wind model data, the Darwin VAAC reported that during 11-12 September ash plumes from Langila rose to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted W. A thermal anomaly at the summit was identified in satellite data.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the eruption at Lewotolok continued during 7-14 September. White-and-gray plumes rose as high as 700 m above the summit and drifted NWW, SW, and S.

Merapi – Central Java (Indonesia) : BPPTKG reported that both of Merapi’s two lava domes, situated just below the SW rim and in the summit crater, continued to grow during 3-9 September. The SW dome grew 5 m taller and had an estimated volume of 1.55 million cubic meters and the summit lava dome grew 1 m wider and had an estimated volume of 2.85 million cubic meters. One pyroclastic flow traveled 2 km down the SW flank and as many as 129 lava avalanches traveled a maximum of 2 km SW. According to the Darwin VAAC ash plumes rose 3 km (10,000 ft) a.s.l. and drifted E on 9 September, based on satellite and webcam views.

Nevados de Chillan – Chile : SERNAGEOMIN reported continuing explosive and effusive activity at Nevados de Chillán’s Nicanor Crater during 16-31 August, though weather conditions often prevented visual confirmation. Explosions generated ash plumes that rose as high as 1.1 km above the crater rim and were denser towards the end of August. Crater incandescence was sometimes visible at night, and though not intense, it brightened during explosive periods. The L5 and L6 lava flows continued to advance, though at a very low rate, averaging 1 m/h for L5. The L5 lava flow was 1,380 m long and L6 was 850 m long based on satellite images, measured from the rim of Nicanor Crater to the distal end of the flows. A decrease in thermal anomalies over the flows identified in satellite images suggested that the flows were cooling. The average temperature was 73 degrees Celsius with a maximum of 100 degrees for L5 and an average of 79 degrees Celsius with a maximum of 100 degrees for L6. Temperatures at the vents at Nicanor Crater averaged 115 degrees Celsius and were as high as 252 degrees during explosive phases. Sulfur dioxide emissions measured from local DOAS stations abruptly decreased and remained low. There was a total of five thermal anomalies, all with low radiance values. On 29 August pyroclastic flows traveled 560 m NE and collapses of L5’s middle and distal parts of the flow were observed.

Pavlof – United States : AVO reported that seismicity at Pavlof continued at low levels during 7-14 September and was interspersed with periods of more energetic tremor. Although weather clouds often obscured views, a series of four very minor ash emissions were visible in webcam images for a period of five hours on 10 September. The explosions produced minor and diffuse ash emissions that rose from a vent on the E flank and dissipated within minutes. A small explosion was recorded on 12 September and on 13 September, though cloud cover prevented visual confirmation of both events.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that eruptive activity at Semisopochnoi’s North Cerberus crater continued during 7-14 September. Seismicity was elevated and characterized by periods of continuous tremor. Short-lived explosions lasting several minutes were detected daily in infrasound data. Small ash clouds from the explosions rose 3-4.6 km (10,000-15,000 ft) and dissipated within two hours. Sulfur dioxide emissions were detected in satellite images at altitudes less than 3 km (10,000 ft) a.s.l., sometimes extending downwind for hundreds of kilometers. During 7-9 September periods of lower-altitude ash emissions interspersed with voluminous steam plumes were observed in web camera images moving horizontally by the wind and rising no higher than 1.5 km (5,000 ft) a.s.l.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a bright thermal anomaly over Sheveluch was identified in satellite images during 3-10 September. The Kamchatka Branch of Geophysical Services (KBGS; Russian Academy of Sciences) Kamchatka volcano station reported that tourists visiting the volcano on 8 September experienced ashfall; weather conditions prevented views of summit. The next day they saw a small pyroclastic flow and that night saw crater incandescence and small incandescent avalanches traveling SE.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that four explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 3.3 km above the crater rim during 3-10 September. Large volcanic bombs were ejected 500 m from the crater. Crater incandescence was visible nightly.

Taal – Luzon (Philippines) : PHIVOLCS reported that gas-and-steam plumes from Taal rose as high as 2.5 km above the lake during 8-14 September and drifted NE, SE, S, and SW. Sulfur dioxide emissions were 5,246-11,840 tonnes/day during 9-10 and 12-13 September.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 8 September – 14 September 2021

Askja – Iceland : On 9 September IMO raised the Aviation Color Code for Askja to Yellow, noting that inflation that began in early August was ongoing and notably rapid. The uplift was centered at the W edge of Oskjuvatn caldera, which rose a total of 7 cm. The data suggested that magma was accumulating at 2-3.5 km depth.

Fukutoku-Oka-no-Ba – Volcano Islands (Japan) : The Japan Coast Guard reported that during a 12 September overflight of Fukutoku-Oka-no-Ba, observers noted that the W island was unchanged while the E side had been completely eroded and submerged. Yellow-green to yellow-brown discolored water extended from the vent area to the SW, S, and SE, suggesting continuing eruptive activity. Another area of discolored water had an approximate diameter of 2 km and was about 2 km ENE of the volcano. The discolored water prompted JMA to issue a navigation warning to nearby vessels.

La Palma – Spain : Instituto Volcanológico de Canarias (INVOLCAN) reported that a seismic swarm beneath Cumbre Vieja at the S part of La Palma began at 1618 on 11 September and was likely associated with a magmatic intrusion. The swarm intensified in number of events and magnitude, and by 1600 on 12 September a total of 315 earthquakes had been recorded and ranged 8-13 km in depth. The largest event was a M 2.8 (on the Mb_lg scale). On 13 September a scientific committee comprised of representatives from multiple agencies and institutions raised the Alert Level to Yellow (the second lowest level on a four-color scale) for the municipalities of El Paso, Los Llanos de Aridane, Mazo, and Fuencaliente de la Palma. By 0800 on 14 September 2,935 earthquakes had been detected. Larger events were felt by residents during 13-14 September; the largest earthquake was a M 3.9, recorded at 0600 on 14 September. Overall, the events were becoming shallower (8-10 km) and hypocenters migrated slightly to the W. GPS and tiltmeter networks showed deformation totaling 1.5 cm centered over the clusters of epicenters. INVOLCAN noted that 10 seismic swarms have been detected at La Palma since 2017; one in 2017, one in 2018, five in 2020, and three in 2021. The earthquakes in the previous swarms were deeper, between 20 and 30 km, and were less intense than the current swarm.

Pagan – Mariana Islands (USA) : The U.S. Geological Survey reported that emissions of ash and sulfur dioxide from Pagan were last detected on 6 September, though robust steam plumes occasionally continued to be visible at least through 14 September.

Whakaari/White Island – North Island (New Zealand) : On 14 September GeoNet reported that intermittent ash emissions at Whakaari/White Island continued to be visible during the previous week. Vigorous fumarolic plumes from the active vent area sometimes carried minor amounts of ash downwind at low altitudes and occasionally deposited ash on the island. Periods where ash was visible in the emissions did not correspond to explosive seismic or acoustic signals, suggesting that the ash was produced by weak wall fragments falling into the gas stream through the active vents and not from eruptive activity. Seismicity was characterized by low levels of volcanic tremor and occasional volcanic earthquakes.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 1 September – 7 September 2021

Ebeko – Paramushir Island (Russia) : According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 28-29 August produced ash plumes that rose as high as 1.9 km (6,200 ft) a.s.l. and drifted SE and E.

Fuego – Guatemala : INSIVUMEH reported that 7-15 explosions per hour were recorded during 31 August-7 September at Fuego, generating ash plumes as high as 1.1 km above the crater rim and shock waves that often rattled buildings around the volcano. Ash plumes mostly drifted as far as 15 km SW, W, NW, and N, causing daily ashfall in several areas downwind, including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), Yucales (12 km SW), El Porvenir (8 km ENE), Finca Palo Verde, 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 100-350 m above the summit on most days. On 1 September lahars descended the SE, S, and SW flanks (the Las Lajas, El Jute, and Seca drainages), carrying fine material along with tree branches and blocks 2 m in diameter. Lahars descended the El Jute, Las Lajas, and Ceniza drainages during 6-7 September.

Great Sitkin – Andreanof Islands (USA) : AVO reported that elevated surface temperatures at Great Sitkin and daily small earthquakes were detected during 31 August-7 September, consistent with the growing lava dome. Gas plumes were observed almost daily in satellite data.

Grimsvotn – Iceland : On 1 September the Icelandic Meteorological Office (IMO) stated that the water level of the Skaftá river at Sveinstindur (the closest gauging station at 28 km downstream from the ice margin) rose, suggesting the beginning of a Skaftárhlaup or glacial outburst flood (also called a jökulhlaup), that originated from Grímsvötn’s Western Skaftá caldera. A sulfur odor was also noted in the vicinity of Skaftá and Hverfisfljót. IMO warned that hydrogen sulfide released from the floodwater as it drained from the caldera lake was particularly potent at the river outlet from the ice margin, where concentrations may reach toxic levels. The flow rate in the Skaftá peaked at 520 cubic meters per second downstream near the bridge at Eldvatn on 2 September and then declined to 412 cubic meters per second in the afternoon of 3 September. As a result, the ice shelf began to subside around 2300 on 4 September, dropping 1 m by 1145 the next morning, based on GPS data. On 6 September the discharge rate increased rapidly and peaked at 610 cubic meters per second at 1400, then declined later that day. Data suggested that the peak discharge rate on 6 September was due to a second release of water from the eastern part of the caldera lake. On 7 September the flow rate had increased to 520 cubic meters per second. Based on an overflight IMO concluded that the glacial flooding from both the E and W parts of the lake was smaller in volume and flow rates compared to a similar event in 2018.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that ash plumes from Karymsky were visible in satellite images drifting 50 km NE and E during 26-27 August, and a thermal anomaly over the volcano was visible every day during 26 August -2 September except for on 29 August.

Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, paused on 2 September. Steam-and-gas emissions were seen rising from the crater during 2-7 September.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the eruption at Lewotolok continued during 31 August-7 September. White and gray plumes rose as high as 600 m above the summit and drifted W and NW. Rumbling and banging were heard on most days. Incandescent material was ejected 300 m on 1 September, as far as 1 km SE during 4-5 September, and 200 m during 6-7 September.

Merapi – Central Java (Indonesia) : BPPTKG reported that both of Merapi’s two lava domes, situated just below the SW rim and in the summit crater, continued to grow during 27 August-2 September. The SW dome grew 2 m taller and had an estimated volume of 1.44 million cubic meters and the summit lava dome grew 1 m taller and had an estimated volume of 2.84 million cubic meters. A total of six pyroclastic flows descended the SW flank as far as 2.5 km; as many as 80 lava avalanches traveled a maximum of 2 km SW.

Popocatepetl – Mexico : CENAPRED reported that each day during 31 August-7 September there were 66-102 steam-and-gas emissions from Popocatépetl. Cloudy weather often prevented views of the volcano. Crater incandescence was visible during the morning of 1 September and explosions were recorded at 2135, 2254, and 2345 later that same day. The Washington VAAC noted that ash plumes rose to 5.8-6.1 km (19,000-20,000 ft) a.s.l. and drifted NW and W during 5-6 September based on satellite and webcam views. Explosions were recorded by CENAPRED at 1642 on 5 September and 0820 on 6 September. Emissions had a low ash content during 6-7 September; explosions occurred at 0212 and 0414 on 7 September.

Semeru – Eastern Java (Indonesia) : PVMBG reported that at 0544 on 2 September an observer saw an ash plume from Semeru rising 200 m above the summit and drifting SW. At 0549 on 6 September an ash plume rose 500 m and drifted N.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that eruptive activity at Semisopochnoi’s North Cerberus crater continued during 31 August-7 September. Multiple daily explosions were detected by seismic and infrasound networks. Ash-and-steam plumes from the explosions were sometimes confirmed in satellite and webcam images rising to altitudes lower than 3 km (10,000 ft) a.s.l., though during 6-7 September ash plumes rose as high as 4.6 km (15,000 ft) a.s.l. Local ashfall on the island was visible in satellite data. Sulfur dioxide emissions were detected in satellite images during 31 August-2 September and on 6 September.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 27 August-3 September. A gas-and-steam plume with some ash was visible in satellite data drifting 54 km NE and NW on 26 and 28 August.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that three explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 4.8 km above the crater rim during 27 August-3 September. Large volcanic bombs were ejected 700 m from the crater. Crater incandescence was visible nightly and ashfall was often reported in Toshima village (4 km SSW).

Telica – Nicaragua : INETER reported that at 0525 on 1 September an explosion at Telica produced an ash plume that rose 250 m above the crater rim and drifted N and NW. Emissions periodically continued later that day, without explosions, and caused minor ashfall in areas to the NW, W, and SW including in the communities of Aguas Frías, San Pedro Nuevo, and Las Marías (7 km NNW).

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 1 September – 7 September 2021

Askja – Iceland : On 3 September IMO reported that inflation at Askja had begun in early August based on ground deformation data derived from satellite images and continuous GPS data. The uplift was centered at the W edge of Oskjuvatn caldera and vertically deformed at a rate of about 5 cm per month. Data indicated that the source of the inflation was at a depth of about 3 km and caused a volume change of about 0.01 cubic kilometers per month; the source was unknown, though most likely was caused by an influx of magma.

Kilauea – Hawaiian Islands (USA) : HVO reported that ground deformation beneath the S part of Kilauea’s summit ceased on 30 August and the earthquake rate decreased during 30-31 August. The data suggested that a magma intrusion had slowed or stopped. Earthquake rates and ground deformation remained near pre-intrusion levels through 7 September.

Pagan – Mariana Islands (USA) : Continuous gas-and-ash plumes from Pagan were observed in satellite images for most of 1 September, prompting the USGS to raise the Aviation Color Code and the Volcano Alert Level remained at Orange/Watch, respectively. The plumes drifted 150 km NW and SW at an altitude of 3 km (10,000 ft) a.s.l. The emissions briefly paused at 2300 and then resumed; satellite images acquired the next morning, on 2 September, showed gas-and-ash plumes drifting 650 km. A plume of ash and sulfur dioxide was identified in satellite data, drifting 150 km W at an altitude of 1.2 km (4,000 ft) a.s.l. early on 3 September. Ash deposits in and around the crater and on downwind parts of the island were observed in 4 September images. During 4-6 September gas-and-ash plumes rose to 1.5 km (5,000 ft) a.s.l. and drifted at least 400 km W. Sulfur dioxide emissions were observed in satellite data on 6 September; ash emissions paused sometimes during 6-7 September as activity declined. A robust steam plume possibly containing a minor amount of ash was visible in satellite data on 7 September drifting 24 km W at an altitude of 1.5 km (5,000 ft) a.s.l.

Pavlof – United States : AVO reported that seismicity at Pavlof was low, though elevated above background levels during 31 August-7 September. Inclement weather sometime prevented satellite and webcam views of the volcano. A sulfur dioxide plume was visible in satellite images on 2 September.

Whakaari/White Island – North Island (New Zealand) : GeoNet reported that beginning at 0630 on 2 September minor ash emissions from the active vent at Whakaari/White Island were visible in webcam images. The emissions were observed in satellite images drifting SW and reaching the Bay of Plenty coastline. GeoNet noted that short episodes of minor ash emissions had been recorded during the previous few weeks, though none were as sustained as the 2 September episode. Minor ash emissions were also recorded on 3 September, but then ceased. The webcam continued to record nighttime incandescence from the vent, at least through 6 September, suggesting that temperatures were likely 500-600°C. Steam-and-gas plumes were voluminous, and coupled with weather conditions, were easily visible from the coast. Deformation measurement showed a broad area of subsidence around the vent area, possibly from the release of pressurized gas at depth and the more voluminous plumes. Additionally, the ash emissions may have possibly been caused by wall fragments falling into the vent.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 25 August – 31 August 2021

Dukono – Halmahera (Indonesia) : The Darwin VAAC reported that during 24 and 26-27 August white-and-gray ash plumes from Dukono rose 2.3 km (7,000 ft) a.s.l. and drifted W, SW, and S.

Ebeko – Paramushir Island (Russia) : According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 20-21 and 24-25 August produced ash plumes that rose as high as 4.6 km (15,100 ft) a.s.l. and drifted SE. A thermal anomaly was identified in satellite images during 20 and 23-25 August.

Etna – Sicily (Italy) : INGV reported that activity at Etna was concentrated at the Southeast Crater (SEC) during 23-29 August. Gas emissions rose from Bocca Nuova crater. A series of explosions at SEC that began at 1530 on 27 August and continued through the next morning produced ash puffs. Strombolian activity began in the early afternoon of 29 August and within an hour, lava fountains were visible rising up to 400 m above the vent. Ash emissions rose a few hundred meters. The activity varied in intensity and during intense periods, ash plumes rose up to 10 km above the summit. Ash and lapilli fell in areas to the E, including in Fornazzo, Milo, San Alfio, and Giarre. Lava flows from the SEC traveled SW and one from the E base traveled E toward the Valle del Bove.

Great Sitkin – Andreanof Islands (USA) : AVO reported that the lava dome at Great Sitkin continued to grow, reaching 880 m in diameter by 25 August and 1,090 m during 28-29 August. Elevated surface temperatures and small earthquakes were detected during 25-31 August, consistent with the growing dome.

Kadovar – Papua New Guinea : Based on satellite and wind model data, the Darwin VAAC reported that on 27 and 30 August ash plumes from Kadovar rose to altitudes of 1.2-1.5 km (4,000-5,000 ft) a.s.l. and drifted W and WNW.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that during 20-27 August daily gas-and-ash plumes from Karymsky were identified in satellite images drifting 94 km NE, E, and SE. Daily thermal anomalies were also visible. The Tokyo VAAC noted that during 25-27 August ash plumes rose to 3-4.6 (10,000-14,000 ft) a.s.l. and drifted E and NE.

Katmai – United States : AVO reported that on 28 August strong winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes picked up unconsolidated ash and drifted SE towards Kodiak Island at an altitude up to 1.8 km (6,000 ft) a.s.l. The ash was originally deposited during the Novarupta eruption in 1912.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the eruption at Lewotolok continued during 25-30 August. White, gray, and sometimes black plumes rose as high as 1.2 km above the summit and drifted W and NW.

Merapi – Central Java (Indonesia) : BPPTKG reported that of Merapi’s two lava domes, the dome just below the SW rim was more active than the dome in the summit crater during 20-26 August. The SW dome grew and shed material down the flanks, increasing in height by just 3 m overall. On 25 August the volume of the SW dome was estimated at 1.4 million cubic meters and the summit lava dome was stable at an estimated 2.831 million cubic meters. A total of two pyroclastic flows descended the SW flank as far as 2 km; as many as 211 lava avalanches traveled a maximum of 2 km SW. Based on satellite images the Darwin VAAC noted that during 28-29 August ash plumes rose to 3-3.7 km (10,000-12,000 ft) a.s.l. and drifted SW, W, and NW.

Nevado del Ruiz – Colombia : Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 25-31 August seismicity at Nevado del Ruiz had generally decreased compared to the previous week. Deformation data indicated minor changes. Gas-and-steam emissions were sometimes visible in satellite data and webcam images rising as high as 1.2 km above the summit and drifting NW and W. These emissions sometimes contained ash; on 26 August an ash emission rose 490 m and drifted WNW.

Rincon de la Vieja – Costa Rica : OVSICORI-UNA reported that small eruptive events at Rincón de la Vieja were recorded at 1915, 2049, and 2053 on 26 August, though weather conditions prevented visual confirmation of emissions. A one-minute-long phreatic eruption was recorded at 1446 on 27 or 28 August and produced an eruption plume that rose 1 km above the crater rim.

Sabancaya – Peru : Instituto Geofísico del Perú (IGP) reported a daily average of 36 explosions at Sabancaya during 23-30 August. Gas-and-ash plumes rose as high as 3.5 km above the summit and drifted S, SW, N, and NE. Ten 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).

Semeru – Eastern Java (Indonesia) : PVMBG reported that at 0718 on 26 August an ash plume from Semeru rose 500 m above the summit and drifted SW.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that the lava dome at Sheveluch continued to grow and produced hot lava avalanches during 20-27 August. A daily bright thermal anomaly was identified in satellite images and gas-and-steam plumes containing some ash drifted 307 km NE, E, and SE. At 1100 on 29 August an ash plume 14×15 km in dimension drifted 30 km W at altitudes of 2.5-3 km (8,200-10,000 ft) a.s.l. On 28 August the Kamchatka Branch of Geophysical Services (KBGS; Russian Academy of Sciences) posted photos of the incandescent dome and avalanches, noting that small landslides and hot avalanches periodically traveled down the S and SE flanks of the dome. Larger landslides were observed 2-4 times per night.

Sinabung – Indonesia : PVMBG reported that on most days during 25-31 August white gas-and-steam plumes from Sinabung rose as high as 500 m above the summit and drifted in multiple directions. Lava avalanches traveled 700 m down the flanks on 25 August.

Stromboli – Aeolian Islands (Italy) : INGV reported that during 23-29 August activity at Stromboli was characterized by ongoing explosive activity from three vents in Area N (North Crater area) and six vents in Area C-S (South-Central Crater area). Explosions from the N1 vent (Area N) ejected lapilli and bombs 80 m high, and produced minor ash emissions. Explosions at N2 vents (Area N) averaged 4-5 events per hour and ejected material 80 m high. Explosions from the S1 and S2 vents in Area C-S were sporadic and occurred at a rate of 5-12 per hour; coarse material was ejected 120 m high. Gas emissions rose from the C vent.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that 15 explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 3.2 km above the crater rim during 20-27 August. Large volcanic bombs were ejected 300 m from the crater. Crater incandescence was visible nightly and ashfall was often reported in Toshima village (4 km SSW); a large amount of ash fell in the village on 26 August. At 1231 on 28 August an eruption produced an ash plume that rose 4.8 km above the crater.

Yasur – Vanuatu : On 26 August the Vanuatu Meteorology and Geo-Hazards Department (VMGD) reported that seismic data and recent visual observations at confirmed ongoing explosions and gas-and-ash emissions. The Alert Level remained at 2 (on a scale of 0-4).

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 25 August – 31 August 2021

Atka – Andreanof Islands (USA) : AVO lowered the Aviation Color Code and Volcano Alert Level for the Atka Volcanic Complex to Green and Normal, respectively, on 27 August, noting that seismicity had returned to baseline levels over the previous week.

Chirinkotan – Kuril Islands (Russia) : SVERT reported that during 23-26 August ash plumes from Chirinkotan were visible rising 2.5-3.5 km (8,200-11,500 ft) a.s.l. and drifting S and SW.

Fukutoku-Oka-no-Ba – Volcano Islands (Japan) : The Japan Coast Guard reported that during a 26 August overflight of Fukutoku-Oka-no-Ba, observers noted that the W island was unchanged while the E side had mostly eroded, leaving two small islands. While no eruptions were visible, gray material from the central vent was intermittently ejected to the sea surface and brown, discolored water was widely distributed, especially to the W.

Kilauea – Hawaiian Islands (USA) : HVO reported that a seismic swarm and ground deformation continued beneath the S part of Kilauea’s summit during 24-25 August. The rate of earthquakes per hour peaked at 28 during 1900-2000 on 24 August and then decreased to 5-12 through 25 August. Most of the earthquakes were between magnitudes 1 and 2, occurring at depths of 1-2 km. By 26 August seismicity and ground deformation levels had decreased, suggesting magma was no longer moving; HVO lowered the Volcano Alert Level and Aviation Color Code to Advisory and Yellow, respectively. Later that day, ground deformation began again in the S part of the caldera at around 1800 and was followed by an increase in seismicity after 2030. Earthquakes in the swarm were located at depths of 1-3 km. The strongest earthquake was a M 2.8, though the majority were less than M 1. The rate of events per hour was 16, with a peak of 24 just after midnight on 27 August, and then declined to about six. Seismicity remained low through 30 August with 7-8 events per hour, all under M 2 and at depths of 1-4 km. Deformation continued to be detected at variable rates. Although the deformation and seismicity suggested renewed magma movement, the data did not indicate an upward movement of magma.

Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the volcanic system, close to on the Reykjanes Peninsula, continued during 25-31 August, though weather often obscured the view of the vents. Low lava fountaining and overflows from the main vent were interspersed with periods of calm. Parts of the crater sometimes collapsed and produced minor ash clouds based on webcam views. According to a news article, lava flowed into the S part of Meradalir valley and then down a hillside into Nàtthagi valley on 26 August in multiple branches. Observers noted that parts of the flows were turbulent and splashed above the flow surface. Lava stopped advancing at around 1600 as the eruption paused. A geophysicist noted that lava had been flowing S more often due to the new vent that had opened on the flank of the cone during the previous few weeks. The Aviation Color Code remained at Orange due to the lack of ash and tephra emissions, though IMO warned of the potential for lapilli and scoria fallout within a 650 m radius of the active vent. Authorities also warned of gas emission hazards.

Pavlof – United States ; AVO reported that several small daily explosions at Pavlof were recorded by seismic and infrasound sensors during 24-26 August. A pilot observed an ash plume from an explosion that rose to 3.7 km (12,000 ft) a.s.l on 25 August. Seismicity was relatively quiet during 27-31 August; elevated surface temperatures continued to be recorded on most of those days. One explosion on 28 August produced an ash emission visible in webcam data.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that eruptive activity at Semisopochnoi’s North Cerberus crater continued during 25-31 August. Multiple daily explosions were detected by seismic and infrasound networks. Ash-and-steam plumes from the explosions were sometimes confirmed in webcam images, in satellite data, and by nearby observers; plumes rose no higher than 3 km (10,000 ft) a.s.l. and produced local ashfall on the island. Daily sulfur dioxide emissions were identified in satellite images, drifting as far as 300 km NW during 29-31 August.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 18 August – 24 August 2021

Atka – Andreanof Islands (USA) : AVO reported that small earthquakes and seismic tremors at Atka continued to be detected, though at near background levels during 18-24 August.

Ebeko – Paramushir Island (Russia) : According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, and the Tokyo VAAC, explosions continued during 14-20 August and produced ash plumes that rose as high as 3 km (10,000 ft) a.s.l and drifted S, SE, E, and NE. Thermal anomalies were detected in satellite imagery on 13 and 14 August. On 25 August an explosion produced an ash plume that rose to 3.7 km (12,000 ft) a.s.l. and drifted 10 km SE.

Fuego – Guatemala : INSIVUMEH reported that 6-13 explosions per hour were recorded during 18-25 August at Fuego, though the weather sometimes prevented visual confirmation. The resulting ash plumes rose to 4.5-4.8 km (14,800-15,700 ft) a.s.l. and drifted as far as 15 km W, SW, S, and NW, causing daily ashfall downwind in Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), Yucales (12 km SW), El Porvenir (8 km ENE), and Yepocapa (8 km NW). White gas-and-steam plumes rose to 4.5 km (14,764 ft) a.s.l. on 19 and 25 August. Shock waves often rattled buildings around the volcano as far as 15 km from the summit. Block avalanches accompanied the explosions, descending the Santa Teresa, Ceniza (SSW), Taniluyá (SW), Trinidad (S), Seca (W), Las Lajas (SE), and Honda drainages, sometimes reaching vegetated areas. Incandescent ejecta was visible rising 100-400 m above the summit during the nights and early mornings of 20-23 August.

Great Sitkin – Andreanof Islands (USA) : AVO reported that the lava dome at Great Sitkin remained active during 17-24 August; satellite imagery showed changes from a diameter of 800 m on 17 August to 850-860 m throughout 18-21 August. Elevated surface temperatures and daily small earthquakes were consistent with an active dome. Gas-and-steam plumes were visible to local ground observers and in satellite imagery during 20-22 and 24 August.

Ibu – Halmahera (Indonesia) : PVMBG reported that during 18-24 August gray-and-white ash plumes from Ibu rose 200-800 m above the summit and drifted N, W, and NW. On 18 August at 0810 an ash plume rose 800 m above the summit and drifted W. A thermal anomaly was visible in satellite images during 22-23 August, according to the Darwin VAAC.

Kadovar – Papua New Guinea : Based on satellite and wind model data, the Darwin VAAC reported that on 19 August an ash plume from Kadovar rose to an altitude of 1.2 km (4,000 ft) a.s.l. and drifted NW.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that ash emissions from Karymsky were observed in satellite data during 14-20 August; gas-and-steam plumes containing some ash were also noted. The Tokyo VAAC reported that multiple ash plumes rose to 2.4-3.4 km (8,000-11,000 ft) a.s.l. and drifted SE, SW, S, and E during 17-21 August. On 19 August an explosion produced an ash plume that rose 2-2.5 km (6,600-8,200 ft) a.s.l and drifted 60 km ESE. Ash plumes during 19-20 August rose to 2.4 km (8,000 ft) a.s.l. and drifted E. A thermal anomaly was identified in satellite imagery all week.

Langila – New Britain (Papua New Guinea) : Based on analyses of satellite imagery and wind model data, the Darwin VAAC reported that on 20 August ash plumes from Langila rose to 2.4 km (8,000 ft) a.s.l. and drifted WNW. A thermal anomaly was observed at the summit based on satellite imagery on 20 August.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that daily white, gray, and sometimes black plumes from Lewotolok rose 50-1,500 m above the summit and drifted SW, NW, and W during 18-24 August. Eruptive activity on 18 and 22 August generated an ash plume that rose 1 and 1.5 km above the summit, respectively, both of which drifted W. Material was ejected as far as 500 m SE on 18 August. On 22 August at 1244 an ash plume was reported 1.5 km above the summit and drifted generally W.

Merapi – Central Java (Indonesia) : BPPTKG reported that both the lava dome just below Merapi’s SW rim and the lava dome in the summit crater remained active during 13-19 August. Webcam images showed some changes in the SW dome due to lava avalanches and pyroclastic flows; there were no significant changes in the central dome. The volume of the SW lava dome was 1.35 million cubic meters. During 13-19 August a total of 20 pyroclastic flows were observed descending the SW flank as far as 3.5 km. Lava avalanches were observed 172 times to the SW, traveling up to 2 km. BNPB noted that ashfall was reported in several areas on 16 August, including Dukun, Sawangan, Tegalrejo, Secang, Gowok, Mertoyudan, Selo, Mojotengah, Temanggung, Kedu, Pringsurat, Bulu, Tlogomulyo, Kranggan, and Parakan. PVMBG reported that during 18-19 and 23-24 August white plumes rose 20-200 m above the crater and drifted in different directions. As many as 331 lava avalanches traveled a maximum distance of 1.5 km SW. Two pyroclastic flows moved as far as 2 km, though the direction was not observed.

Pacaya – Guatemala : INSIVUMEH reported that white-to-blue gas-and-steam emissions rose as high as 600 m above Pacaya’s Mackenney crater and drifted as far as 2 km S, SW, and N during 18-25 August. Seismic stations recorded some weak explosion and degassing events on 18 August.

Reventador – Ecuador : IG reported that several ash emissions from Reventador during 18-24 August rose 500-1,400 m above the summit and drifted NW, W, SW, and S; sometimes weather conditions prevented visual confirmation. Seismicity was characterized by daily explosions, harmonic tremor, long-period earthquakes, and signals that indicated emissions. The Washington VAAC reported gas-and-steam and ash plumes to 1.4 km above the summit that drifted W, NW, and SW, often observed multiple times per day in satellite imagery or webcams. Nighttime crater incandescence was frequently observed, accompanied by incandescent blocks rolling down the NE, E, and S flanks as far as 600 m. A lava flow was reported traveling down the NE flank during 17-18 August.

Sangay – Ecuador : IG reported gas-and-ash emissions from Sangay rising 500-1,500 m above the summit that drifted W and SW during 19-20 and 24 August. During 20-23 August gas-and-steam plume rose 1-2 km above the summit and drifted W, SW, and NW. Weather clouds and rain sometimes prevented visual and webcam observations of the volcano. Ash plumes were identified in satellite images by the Washington VAAC, rising 570-1,500 m above the volcano and drifting W and SW during 19-21 and 23-24 August. During the evening on 19 August explosions accompanied by incandescent blocks were reported around 1852 rolling down the SE drainage. Signals indicating lahars were recorded by the seismic network during 18-19 and 22-23 August.

Santa Maria – Guatemala : INSIVUMEH reported that daily ash plumes from Santa Maria’s Santiaguito lava-dome complex during 18-25 August rose to 2.8-3.5 km (9,200-11,500 ft) a.s.l. and drifted as far as 8 km W and SW. Ashfall was reported in San Marcos (8 km SW), Loma Linda Palajunoj (6 km WSW), and surrounding farms on 24 August. An active lava flow 600 m long extended down the W and S flanks of the dome during 18-24 August. Collapses of blocky lava from the Caliente dome generated block-and-ash avalanches down the W, S, and SW flanks, often reaching the base and causing minor ashfall on the flanks. Weak explosions accompanied these avalanches on 21 August and generated abundant gas-and-steam emissions. Nighttime incandescence was often observed from the lava flow and dome.

Semeru – Eastern Java (Indonesia) : PVMBG reported that a vertical gray-and-white plume from Semeru rose 400-500 m above the summit and drifted SW on 19 August. This eruption continued during 20-24 August, but the height of the plume was not observed due to cloud cover.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that multiple explosions and seismicity at Semisopochnoi’s North Cerberus crater continued during 18-24 August. Low-level gas-and-ash emissions, including occasional sulfur dioxide emissions were detected in satellite and webcam data during 18-24 August and rose no higher than 3 km (10,000 ft) a.s.l.; views were often obscured due to weather. On 20 August minor ashfall deposits were reported; ashfall may have continued following explosive events during the rest of the week.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that the growth of the lava dome at Sheveluch continued during 14-24 August, accompanied by strong fumarolic activity, dome incandescence, and hot avalanches. A thermal anomaly was identified in satellite imagery all week. Gas-and-steam plumes containing some ash drifted 370 km SW, E, and SE. On 21 and 24 August ash plumes rose to 4 km (13,100 ft) a.s.l. and drifted 86 km SE and 3.5 km (11,500 ft) a.s.l. and drifted as far as 100 km SE, respectively. The Tokyo VAAC reported ash plumes during 17-25 August that rose to 3.7-5.5 km (12,000-18,000 ft) a.s.l. and drifted E, S, SE.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that explosions at Suwanosejima’s Ontake crater were detected on 19, 20, and 21 August. The first explosion at 0137 on 19 August produced an ash plume that rose 3 km above the crater and drifted NE, followed by another at 1613 that generated an ash plume 2.2 km above the crater and drifted N. A small amount of ashfall was reported in Yakushima, Nishinoomote, and Nakatane. A third explosion at 2059 that day produced an ash plume that rose 2.5 km above the crater and drifted N; ashfall was reported in Toshima village (4 km SSW). Explosions at 0628 and 0713 on 20 August generated ash plumes that rose 2.5-3 km above the crater and drifted N, resulting in ashfall in Toshima village, with smaller amounts of ash in Yakushima, Mishima, Ibusuki, Minamikyushu, and Makurazaki. On 21 August at 0617 an explosion generated an ash plume that rose 3.2 km above the crater and drifted N. A large amount of ashfall (over 1 mm) was reported in Toshima village and smaller amounts (less than 0.1 mm) were reported in Makurazaki, Minamisatsuma, Minamikyushu, Kagoshima, Ibusuki, and Hioki. A second explosion followed at 0906 that produced an ash plume 3.2 km above the crater that drifted N. The Tokyo VAAC reported ash plumes to 1.5-3.9 km (5,000-13,000 ft) altitude that drifted NE during 18-25 August.

Taal – Luzon (Philippines) : PHIVOLCS reported that gas-and-steam plumes from Taal rose 1-3 km and sulfur dioxide emissions peaked at 15,347 tonnes/day on 19 August and declined to an average of 8,351 tonnes/day during 13-19 August.

Tengger Caldera – Eastern Java (Indonesia) : PVMBG reported that during 18-24 August white gas-and-steam plumes rose 50-400 m above Tengger Caldera’s Bromo cone and drifted SW, W, and NW. A weak thermal anomaly was visible in Sentinel-2 infrared satellite images on 23 August.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 18 August – 24 August 2021

Chirinkotan – Kuril Islands (Russia) : SVERT and KVERT reported that moderate eruptive activity continued at Chirinkotan during 14-23 August, characterized by explosions and ash plumes that rose to 2.5-4.5 km (4,900-9,800 ft) a.s.l. and drifted as far as 125 km S, E, SE, and SW. At 1110 on 18 August an explosion produced an ash plume, 20 x 27 km in size, that rose to 2-3 km (6,600-9,800 ft) a.s.l. and drifted 7 km NE and as far as 100 km SE. An explosion at 0935 on 23 August rose to 1.5-2.5 km (4,900-8,200 ft) a.s.l. and drifted 8 km SW and later, as far as 126 km W. The Tokyo VAAC reported ash plumes to 2.7-4.9 km (9,000-16,000 ft) a.s.l. that drifted S, NE, and SW during 18 and 23 August. .

Fukutoku-Oka-no-Ba – Volcano Islands (Japan) : The Japan Coast Guard reported that the eruption at Fukutoku-Oka-no-Ba continued during 16-22 August. Gas-and-steam emissions continued to be observed from the center of the island on 16 August. The pumice raft that was first identified on 15 August had expanded to about 100 km to the WNW and was about 13 km wide. Brown discoloration was visible surrounding the new island, which had a variable shape but a consistent diameter of 1 km by 16 August. A local fisherman in the Ogasawara Islands who was fishing in South Iwo Jima (5 km NNE) posted photos and videos on 17, 20, and 22 August that showed strong white gas-and-steam plumes rising above the volcano. On 20 August lightning was visible within the gas-and-steam plume. On 22 August the plume was observed during 0430-0630.

Kilauea – Hawaiian Islands (USA) : HVO reported that a swarm of earthquakes beneath the S part of Kilauea that began at 1630 on 23 August continued into the early morning of 24 August. The earthquake swarm increased in intensity at 0130 and was accompanied by an increase in the rate of ground deformation to the W of the swarm, as recorded by the Sandhill tiltmeter. This possibly indicated that there was magma movement 1-2 km beneath the S part of the caldera. Over 140 earthquakes were recorded during 24 August, the largest of which was an Mw 3.3; a majority of them were less than Mw 1. Small earthquakes continued at a rate of at least 10 earthquakes per hour through 24 August.

Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 18-24 August, though weather often obscured the view of the vents. During 18-19 August new lava flows were observed overflowing the SW and NE crater rims and traveling S, E, and SE in the Geldingadalur and Meradalir valleys. Gas-and-steam plumes often accompanied these flows. On 20 August a large collapse from the inner crater rim was observed in video images (Langihryggur camera), generating some ash emissions. Lava flows traveled toward the Nàtthagi valley during 21-24 August, based on webcam data. Video taken during 21-22 August showed some lava fountaining and flows overflowing the sides of the main cone, accompanied by white gas-and-steam emissions.

Pavlof – United States : AVO reported that occasional small explosions and elevated seismicity at Pavlof were detected in geophysical data during 18-19 August; clouds often obscured the view of the volcano. Observations from webcams and pilots indicated minor low-level ash emissions during 18-19 August. Weakly elevated surface temperatures were frequently detected during 18-22 August in the active vent based on satellite and webcam data.

 

Whakaari/White Island – North Island (New Zealand) : GeoNet maintained the Volcanic Alert Level at 2 and the Aviation Color Code at Yellow for Whakaari/White Island. A volcanic earthquake was recorded at 1900 on 19 August that continued for ten minutes; other seismic activity has been minor. Webcam images showed some incandescence during the night, which suggested that temperatures in the vent area were likely 500-600°C. On 22 August at 0740 a period of minor ash emissions was observed from the active vent area that lasted for two minutes, based on webcam images. Low levels of ground deformation around the active vent and lake area were identified in satellite radar data.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 11 August – 17 August 2021

Ebeko – Paramushir Island (Russia) : According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 6-9 and 11 August produced ash plumes that rose as high as 2.5 km (8,200 ft) a.s.l. and drifted E and SE. A thermal anomaly was identified in satellite images on 6, 9, and 11 August.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that explosions at Karymsky during 6-13 August produced ash plumes that rose as high as 2.5 km (8,200 ft) a.s.l. Gas-and-steam plumes containing some ash drifted over 60 km SE and SE. A thermal anomaly was identified in satellite images during 7-8 August.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 11-17 August. White, gray, and sometimes black plumes rose as high as 2 km above the summit and drifted S, NW, and W during 10-12 August. Incandescent lava was ejected 200-350 m radially on 10 August, accompanied by banging noises. Ash plumes rose 100-300 m during 13-17 August and drifted NE and W. Incandescence from the SW part of the crater was visible during 15-16 August.

Merapi – Central Java (Indonesia) : BPPTKG reported that both the lava dome just below Merapi’s SW rim and the lava dome in the summit crater remained active during 5-12 August. The domes grew and shed material down the flanks, resulting in relatively stable dome volumes. A total of 28 pyroclastic flows descended the SW flank as far as 3 km; as many as 252 lava avalanches traveled a maximum of 2 km SW and one traveled 500 m SE. BNPB noted that ashfall was reported in 19 villages on 10 August and several on 12 August, in the districts of Dukun, Sawangan, Grabag, Pakis, Tegalrejo, Secang, Srumbung, Salam, Muntilan, and Mungkid. Winds played a role in the extensive distribution of ashfall.

Rincon de la Vieja – Costa Rica : OVSICORI-UNA reported that eruptive events at Rincón de la Vieja were recorded at 1052 on 12 August and 0703 on 13 August, though weather conditions prevented visual confirmation of emissions. Fumarolic activity within the crater increased during 16-17 August.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 6-13 August. Gas-and-steam plumes containing some ash drifted 140 km SW during 7 and 9-12 August. On 11 August the Kamchatka Branch of Geophysical Services (KBGS; Russian Academy of Sciences) reported that the spine had crumbled and incandescent material descended the flanks.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that 10 explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 2.2 km above the crater rim during 6-13 August. Large volcanic bombs were ejected 400 m from the crater. Crater incandescence was visible nightly and ashfall was occasionally reported in Toshima village (4 km SSW).

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 11 August – 17 August 2021

Atka – Andreanof Islands (USA) : The number of small shallow earthquakes increased at Atka during 10-11 August, prompting AVO to raise the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. The earthquakes were located at a depth of 3-6 km and around 7 km SW of Korovin, though may be related to the several vents that are part of the Atka volcanic complex. Seismicity declined afterwards but remained above background levels through 16 August, and was near baseline levels by 17 August.

Chirinkotan – Kuril Islands (Russia) : KVERT reported that the eruption at Chirinkotan continued during 11-17 August. An explosion at 1315 on 14 August produced a 15 x 17 km ash plume that rose 3-3.5 km (10,000-11,500 ft) a.s.l. and drifted 13 km SSE. Ash plumes from an explosion at 0945 on 15 August rose 2.5-3 km (8,200-10,000 ft) a.s.l. and drifted 8 km S. KVERT and SVERT noted that another explosive event at 1010 on 16 August generated ash plumes that rose 3.5-5 km (11,500-16,400 ft) a.s.l. and drifted 23 km E.

Fukutoku-Oka-no-Ba – Volcano Islands (Japan) : JMA reported that a large eruption at Fukutoku-Oka-no-Ba commenced around 0620 on 13 August based on satellite data. Ash plumes rose as high as 16 km (54,000 ft) a.s.l. and drifted W. The eruption was also confirmed during an overflight later that day. Video showed Surtseyan explosions ejecting black material above the ocean’s surface, and ash plumes drifted W. Ash plumes identified in satellite images rose 12.2-16 km (40,000-54,000 ft) a.s.l. during 13-15 August; the height of the plume decreased afterwards though the eruption intermittently continued. The Japan Coast Guard observed a new horseshoe-shaped island that was about 1 km in diameter during an overflight on 15 August. They also observed and photographed a notable pumice raft swirling with the currents as far as 60 km NW. JMA noted that the volcano last erupted in 2010 and frequent episodes of discolored seawater had been observed since then.

Great Sitkin – Andreanof Islands (USA) : AVO reported that the lava dome at Great Sitkin continued to be active, growing in diameter from 250 m on 6 August, to 380 m three days later, and to 700 m by 16 August. Steam-and-gas plumes were periodically observed in webcam images, in satellite data, and by observers on the ground during 11-17 August. Elevated surface temperatures and small earthquakes detected daily were consistent with the growing dome.

Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 11-17 August. According to the Institute of Earth Sciences photographs of the flow field captured on 8 August suggested that the lava effusion rate averaged 9.3 cubic meters per second over the previous 12 days. The area of the flow field had grown to 4.4 square kilometers, and the total volume erupted was 119 million cubic meters. New ground cracks were observed in Gónhóll, a hill S of the main crater (the fifth vent) that was a former vantage point but is now surrounded by lava, though they had likely formed sometime in the previous two weeks and may not have been caused by rising magma. A new vent that opened on 9 August was not confirmed to be separate from the nearby main vent until about a week later. The new cone quickly grew from intense spattering and by 17 August was around the same height as the main crater. Spattering from the new vent was at times ejected higher than spatter from the main vent.

Nishinoshima – Japan : JMA reported that ash plumes from Nishinoshima were visible in satellite images on 14 August rising about 1.9 km and drifting N. The Japan Coast Guard conducted an overflight the next day and did not observe eruptive activity or new deposits from the day before. The Tokyo VAAC noted that a period of continuous ash emissions was visible in satellite data on 15 August.

Pacaya – Guatemala : INSIVUMEH reported that gas emissions rose as high as 1.1 km above Pacaya’s summit and drifted as far as 1 km S and SW during 10-17 August. Two explosions produced ash plumes that drifted S on 13 August.

Pavlof – United States : AVO reported that several small daily explosions at Pavlof were recorded by seismic and infrasound sensors during 10-17 August. The vent producing the explosions was possibly near the 2007 vent location on the upper SE flank. Small ash emissions, visible in webcam images and occasionally observed by pilots, dissipated quickly and likely deposited ash no further on the upper flanks.

Sarychev Peak – Matua Island (Russia) : SVERT reported that an emission of sulfur dioxide from Sarychev Peak was identified in satellite data on 15 August.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that an eruption at Semisopochnoi’s North Cerberus crater was ongoing during 11-17 August, characterized by daily explosions, ash plumes, and occasional sulfur dioxide emissions identified in satellite images. Multiple energetic explosions were detected daily in seismic and infrasound data, and strong seismic tremor was occasionally recorded. Daily steam-and-ash plumes identified in webcam and satellite data rose no higher than 3 km (10,000 ft) a.s.l. and drifted 200-300 km W. Daily ashfall likely occurred on the island.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 4 August – 10 August 2021

Aira – Kyushu (Japan) : JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 2-9 August. Very small eruptive events were recorded during 2-6 August. The sulfur dioxide emission rate was relatively elevated at 1,500 tons per day on 4 August. 

Asamayama – Honshu (Japan) : On 6 August JMA lowered the Alert Level for Asamayama to 1 (on a scale of 1-5), noting that the number of shallow volcanic earthquakes had been decreasing, sulfur dioxide gas emissions had been low, and deformation on the W flank had stabilized. 

Copahue – Central Chile-Argentina border : SERNAGEOMIN and SEGEMAR reported increased activity at Copahue during 9-10 August, characterized as increased gas emissions, ash emissions, and crater incandescence. During the morning of 9 August gas-and-steam emissions increased and sulfur dioxide flux was as high as 7,200 tons per day. Crater incandescence was visible in nighttime webcam views and was intense during the early hours of 10 August. An ash plume rose 300 m above the crater rim and drifted N and NNW. Seismicity remained stable; data suggested no rising magma. 

Dukono – Halmahera (Indonesia) : PVMBG reported that during 3-4 and 6 August white-and-gray ash plumes from Dukono rose 100-500 m above the summit and drifted E and W. Weather conditions prevented visual observations during 5 and 7-10 August.

Ebeko – Paramushir Island (Russia) : According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 29 July, 1 August, and 3-5 August produced ash plumes that rose as high as 2.5 km (8,200 ft) a.s.l. and drifted S and SE. A thermal anomaly was identified in satellite images on 1 August.

Etna – Sicily (Italy) : INGV reported continuing activity at Etna’s summit craters during 2-8 August, mainly from the Northeast Crater (NEC) and the Southeast Crater (SEC). Gas emissions rose from Voragine Crater and from two active craters in Bocca Nuova. A series of discontinuous ash emissions from NEC began at 1350 on 4 August and lasted about two hours. An ash plume rose to 1.8 km (6,000 ft) a.s.l. and drifted NE. Similar but less intense ash emissions were visible on 5 August. The reddish mostly fine-grained material emitted from NEC was erupted when no thermal anomalies were present in the crater, suggesting that they were the result of landslides rather than eruptive activity. Strombolian activity began at SEC at 2057 on 7 August and was characterized by isolated explosions and the ejection of incandescent material beyond the crater rim; activity ceased during the night. An explosion at 2056 on 8 August was followed by the resumption of Strombolian activity at 0030 on 9 August. Incandescent material was again ejected beyond the crater rim and an ash plume drifted SE.

Fuego – Guatemala : INSIVUMEH reported that 4-13 explosions per hour were recorded during 3-10 August at Fuego, generating ash plumes as high as 1.1 km above the crater rim and shock waves that often rattled buildings around the volcano. Ash plumes mostly drifted as far as 15 km W and SW, causing daily ashfall in several areas downwind, including Morelia (9 km SW), Panimaché (8 km SW), Santa Sofía (12 km SW), Yucales (12 km SW), El Porvenir (8 km ENE), Finca Palo Verde, 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 100-400 m above the summit during 4-6 and 9-10 August. At 1700 on 6 August a lahar descended the Las Lajas drainage, carrying fine material along with tree branches and blocks 1-2 m in diameter.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was identified in satellite images during 29 and 31 July, and 1, 2, and 4 August. Weather clouds prevented satellite observations on the days in between as well as during 5-6 August. Gas, steam, and ash plumes from explosions rose 2.5 km (8,200 ft) a.s.l. and drifted 75 km SE during 1 and 4-5 August.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 3-10 August. Daily white, gray, and sometimes black plumes rose as high as 1.5 km above the summit and drifted in multiple directions. Banging noises associated with eruptions were reported almost daily.

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 remained active during 30 July-5 August. The SW rim dome volume was an estimated 1.895 million cubic meters and about 3 m tall. A total of seven pyroclastic flows descended the SW flank as far as 2 km and as many as 84 lava avalanches traveled a maximum of 2 km SW. Multiple pyroclastic flows traveled 2-3 km down the SW flank on 8 August and ash plumes rose 1 km above the summit. According to a news article ashfall was reported in several local communities. Pyroclastic flows traveled up to 3 km down the SW flanks multiple times during 9-10 August. BNPB noted that a small fire on the SW flank, 2.5 km from the crater, was set by ejected incandescent material; the fire burned an area of only 30 square meters during 25-26 August.

Popocatepetl – Mexico : CENAPRED reported that each day during 4-10 August there were 30-92 steam-and-gas emissions from Popocatépetl. The plumes drifted mainly W and some contained ash. A minor explosion was recorded at 0652 on 4 August. At 2137 on 6 August a moderately-sized explosion produced a plume, thought the height and drift direction were obscured by weather conditions. Incandescent fragments ejected from the crater were seen falling on the flanks not far from the crater rim. Weather conditions again prevented views of an explosion at 0258 on 8 August.

Raung – Eastern Java (Indonesia) : PVMBG reported that neither explosive nor effusive activity had been recorded at Raung since February, and emissions were not observed during 1 July-8 August. Seismicity had declined and deformation data indicated a trend of deflation.

Santa Maria – Guatemala : INSIVUMEH reported that during 4-10 August daily explosions at Santa María’s Santiaguito lava-dome complex generated ash plumes that rose as high as 1 km above the summit and drifted as far as 7 km SW and W. Incandescence from the complex was occasionally visible at night. Collapses of blocky lava from Caliente dome sent avalanches down the S, SW, and W flanks, often reaching the base, and caused minor ashfall mostly on the volcano’s flank. Ashfall was also reported in San Marcos (8 km SW), Loma Linda Palajunoj (6 km WSW), and surrounding farms during 3-4 and 8-9 August. Heavy rainfall on 7 August caused a lahar to descend the Tambor River, carrying branches, tree trunks, and blocks up to 3 m in diameter.

Semeru – Eastern Java (Indonesia) : Semeru continued to erupt during 4-10 August. Inclement weather often prevented visual observations, though during 4-7 August avalanches of lava from the end of the flow in the summit crater were seen traveling 200 m SE down the Kobokan drainage. Gray-and-white plumes rose 500 m above the summit and drifted SW during 6-7 and 9 August.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 30 July-6 August.

Sinabung – Indonesia : PVMBG reported that on most days during 3-10 August white gas-and-steam plumes from Sinabung rose as high as 500 m above the summit and drifted in multiple directions. Avalanches of lava traveled 500-700 m down the E and SE flanks during 4-7 August.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 4 August – 10 August 2021

Chirinkotan – Kuril Islands (Russia) : According to KVERT an explosion at Chirinkotan at 1745 on 8 August produced an ash plume that rose 2-2.7 km (6,600-9,000 ft) a.s.l. and drifted 86 km WSW and SW. KVERT raised the Aviation Color Code to Orange (the second highest level on a four-color scale). KVERT, SVERT, and the VAAC reported continuing ash-producing events through 10 August. Notably at 1915 on 9 August an ash cloud, 10 x 13 km in size, possibly rose as high as 3.7 km (12,000 ft) a.s.l. and drifted 26-30 km SSE and S. An explosive event at 0855 on 10 August produced an ash plume 11 x 14 km in size that rose 2-2.5 km (6,600-8,200 ft) a.s.l. and drifted 70 km W.

Great Sitkin – Andreanof Islands (USA) : AVO reported that unrest continued at Great Sitkin during 4-10 August with elevated seismicity, elevated surface temperatures, and explosions associated with a growing lava dome. Numerous earthquakes and small explosions were recorded on local infrasound and seismic stations during 4-5 August. During the morning of 5 August observers reported possible low-level lava fountaining from the active vent; the activity was also visible from Adak Island. Throughout the same day a volcanic plume comprised mostly of gas and steam (and possibly ash) was visible in webcam images rising to 3 km (10,000 ft) a.s.l. By 6 August the lava dome had grown to 250 m in diameter and had an approximate volume of about 1 million cubic meters. AVO noted that most of the crater was full of lava erupted in 1974 and that the current lava covered only 4-5 percent of the total summit crater area. Elevated surface temperatures were identified in satellite images during 6-10 August.

Nyiragongo – DR Congo : Goma Volcano Observatory (GVO) reported that a gas-and-ash plume rose from Nyiragongo at 1420 on 4 August.

Pacaya – Guatemala : INSIVUMEH reported that explosions at Pacaya were recorded at 0905, 1340, and 1421 on 4 August, a departure from the low levels of activity observed during the previous four months. The explosions produced ash plumes that rose about 1 km above the summit and drifted 12 km N, causing ashfall in Mesías Altas, Mesías Bajas, and Villa Canales. The report noted that the cinder cone in Mackenney Crater had been destroyed during the previous eruption phase and the crater was about 100 m deep. Cracks were seen around the crater indicating areas of instability at the summit. Steam-and-gas plumes rose as high as 1 km above the summit and drifted as far as 3 km in multiple directions during 5-10 August. No explosions were heard or visually observed, though the seismic network recorded weak explosion signals during 6-7 August.

Pagan – Mariana Islands (USA) : Felt earthquakes and minor emissions from Pagan were observed on 29 July. No additional activity had been reported by 6 August; the Aviation Color Code and the Volcano Alert Level remained at Yellow/Advisory, respectively. Seismic, infrasound, and web camera data from the volcano remained unavailable; no activity was observed in satellite images.

Pavlof – United States : Intermittent bursts of ash from the summit of Pavlof were visible in webcam views on 5 August, prompting AVO to raise the Volcano Alert Level and Aviation Color Code to Watch and Orange, respectively. The bursts formed diffuse plumes that rose just above the summit and drifted almost 10 km SE before dissipating. Minor daily ash emissions continued to be observed in webcam images during 5-9 August. The seismic network recorded elevated seismicity (tremor) and small explosions. Several small explosions were recorded during 8-9 August though weather clouds prevented satellite and webcam views.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that an eruption at Semisopochnoi’s North Cerberus crater was ongoing during 4-10 August, characterized by daily explosions, ash plumes, and sulfur dioxide emissions identified in satellite images. Multiple energetic explosions were detected almost daily in seismic and infrasound data. An ash cloud rose to 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted 33 km NE during 3-4 August. Ash emissions were also visible in webcam images and photographed by an observer S of the island. An ash cloud was generated at 2123 on 4 August and was visible in satellite data until 0250 on 5 August, drifting 180 km SE over Gareloi and southern Tanaga Island. A small ash cloud at 2040 on 6 August drifted 50 km beyond the N crater vent and quickly dissipated. Another small ash cloud at 2103 caused ashfall on the webcam located 5 km NE about 30 minutes later. Ash-and-steam emissions were visible in webcam images until 2333. A large infrasound signal was recorded at 0653 on 8 August, though weather conditions prevented visual confirmation of emissions. A possible small ash cloud was visible in a satellite image at 0700. At least three separate explosions were recorded at 1714 on 8 August and 0339 and 0417 on 9 August. A small ash cloud at 900 m (3,000 ft) a.s.l. was visible in satellite images on the morning of 9 August. There were 10 explosions recorded during 9-10 August; small ash-and-steam emissions were visible in the webcam and small low-level plumes were occasionally identified in satellite data.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that 13 explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 3.8 km above the crater rim during 30 July-6 August. Large volcanic bombs were ejected 500 m from the crater. Crater incandescence was visible nightly.

Tengger Caldera – Eastern Java (Indonesia) : PVMBG reported that during 3-9 August white steam-and-gas plumes rose as high as 400 m above Tengger Caldera’s Bromo cone and drifted NW, W, and SW. Thermal anomalies were visible in satellite images on 3 and 8 August; a weaker anomaly was also visible on 29 July.

Whakaari/White Island – North Island (New Zealand) : GeoNet maintained the Volcanic Alert Level at 2 and the Aviation Color Code at Yellow for Whakaari/White Island based on continuing unrest and data collected during a recent overflight. In a 9 August report GeoNet noted that temperatures in the vent area remained high at 520 degrees Celsius; crater incandescence continued to be visible in webcams images at night. Moderate levels of carbon dioxide and sulfur dioxide emissions measured downwind of the volcano were similar to levels observed on 20 July. Low levels of ground deformation around the active vent and lake area were identified in satellite radar data. The interpretation of the data suggested a shallow magma intrusion beginning in June. Very steamy conditions obscured views of the vent area.

Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 28 July – 3 August 2021

Aira – Kyushu (Japan) : JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 26 July-2 August. An eruptive event at 2009 on 28 July produced a plume that rose 1.3 km above the crater rim. A very small eruptive event was recorded on 2 August.

Aniakchak – United States : AVO reported that strong winds in a region N of Aniakchak and E of Port Heiden resuspended ash and blew it N on 2 August. A dense cloud of possible resuspended ash near ground levels was identified in Port Heiden webcam views. The cloud was also visible in satellite data drifting about 200 km N.

Bagana – Bougainville (Papua New Guinea) : The Darwin VAAC reported that on 31 July an ash plume from Bagana rose to 4.6 km (15,000 ft) a.s.l. based on a pilot observation. A few hours later steam emissions were identified in satellite images.

Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 27-30 July and 1-3 August ash plumes from Dukono rose to 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NE, E, and SE.

Ebeko – Paramushir Island (Russia) : A thermal anomaly over Ebeko was identified in satellite images on 25 July. According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 26-28 July produced ash plumes that rose as high as 2 km (6,600 ft) a.s.l. and drifted E.

Gareloi – United States : AVO reported that the elevated seismicity first detected at Gareloi in May had continued through June and then declined to background levels.

Kadovar – Papua New Guinea : Based on satellite and wind model data, the Darwin VAAC reported that on 1 August an ash plume from Kadovar rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted W.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was identified in satellite images during 23-30 July. Multiple explosions during the week produced ash plumes that rose to 2 km (6,600 ft) a.s.l. and drifted about 350 km E.

Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 28 July-3 August. Lava fountaining and overflows from the fifth vent occurred at intervals of 10-15 hours, with similarly long periods of no activity in between; this pattern emerged around 17 July. According to the Institute of Earth Sciences an overflight was conducted on 27 July; based on new measurements, the lava effusion rate averaged 11 cubic meters per second during 2-27 July, though the average since 17 July was likely lower. The area of the flow field had grown to 4.3 square kilometers, and the total volume erupted was 109 million cubic meters. Lava flowed into the Meradalir Valley and areas to the W and did not advance in the Geldingadalur, Nátthaga, and Sydri Meradalir (SE of the fifth vent) valleys. The flows in Meradalir thickened about 1 m per day.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 27 July-2 August. Daily white, gray, and black plumes rose as high as 1 km above the summit and drifted in multiple directions. At 0023 on 28 July an eruptive event accompanied by a loud bang ejected incandescent lava 700-800 m from the crater. At 0722 another event ejected incandescent lava 1 km SE. Vegetated areas on the S and SW flanks caught fire, which quickly spread to the SE and W flanks due to dry conditions, burning forest as far as 2 km from the crater. At 0840 on 30 July lava was again ejected 1 km SE and loud rumbling was reported. By the morning of 30 July, the fire on the flanks was less intense and declining, but remained active at least through 1 August. Banging noises were reported on 31 July and 2 August.

Mayon – Luzon (Philippines) : On 30 July PHIVOLCS lowered the Alert Level for Mayon to 0 (on a 0-5 scale) noting that activity had declined to baseline levels over the previous several months. Ground deformation data indicated tectonic origins rather than magmatic or hydrothermal causes. The frequency of volcanic earthquakes had declined to baseline levels (0-5 events/day) during the previous six months and sulfur dioxide flux had dropped to 156 tonnes/day on 14 July, below the baseline of 500 tonnes/day. Dim crater incandescence from hot gas emissions at the summit continued to be visible in camera images; the last time it was visually observed was in May 2021.

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 remained active during 23-29 July. The SW rim lava-dome volume was an estimated 1.878 million cubic meters and material continued to collapse down the flank. The volume of the summit lava dome was 2.817 million cubic meters. A total of four pyroclastic flows descended the SW flank as far as 2.5 km. Lava avalanches traveled a maximum of 1.2 km SE (29 times), 2 km SW (145 times), 800 m W (four times), and 500 m NW (one time). Avalanches of material that descended the W flank originated from lava emplaced in 1992 and 1998, and material that descended the NW flank is from 1948 lava.

Rincon de la Vieja – Costa Rica : OVSICORI-UNA reported that an eruptive event at Rincón de la Vieja was recorded at 1133 on 1 August, though weather conditions prevented visual confirmation of emissions.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 23-30 July. Activity was notable on 26 July with collapses of lava-dome blocks and small explosions. A gas-and-steam plume with some ash was visible in satellite data drifting 45 km E that same day.

Sinabung – Indonesia : PVMBG reported that at 1320 on 28 July an eruption at Sinabung produced dense ash plumes that rose as high as 4.5 km above the summit that drifted E and S; pyroclastic flows traveled as far as 1 km down the E and SE flanks. The event lasted over 12 minutes, and caused ashfall in areas to the E including the subdistricts of Namanteran, Merdeka, Berastagi, and Simpang Empat. White plumes rose up to 500 m above the summit during 29 July-2 August; weather conditions sometimes prevented visual observations.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that during 26-30 July bombs ejected from Suwanosejima’s Ontake Crater landed as far as 500 m away from the crater and plumes rose as high as 3.3 km above the rim. Explosive activity had been elevated during June and most of July, with ejected bombs landing as far as 1 km from the crater. Activity peaked on 22 July but then declined afterwards.

Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 28 July – 3 August 2021

Dieng Volcanic Complex – Central Java (Indonesia) : PVMBG reported that on 30 July a burst of mud originated from the Siglagah thermal feature (Dieng Volcanic Complex), located on a steep hill, about 1 km NE of the center of Pagerkandang cone. The event caused an audible banging noise and sent a mudflow, 1-3 m thick, 10 m N. Observers that had visited the site in July saw gas emissions rising 10-30 m high and occasionally heard “bursting” noises up to 100 m away. The event was not accompanied by an increase in seismicity.

Great Sitkin – Andreanof Islands (USA) : AVO reported that unrest continued at Great Sitkin during 28 July-3 August. Seismicity remained elevated and a small swarm was recorded during 1-2 August. Elevated surface temperatures and a north-drifting steam plume were identified in satellite images during 27-28 July. Minor steam emissions were visible during 31 July-3 August. The circular lava dome in the crater had grown to 180 m in diameter based on measurements taken using a 3 August satellite image.

Nyiragongo – DR Congo : Goma Volcano Observatory (GVO) reported that a small area of incandescence from the floor of Nyiragongo’s collapsed crater was visible in a 26 July satellite image.

Pagan – Mariana Islands (USA) : Residents reported felt earthquakes and observed minor emissions at Pagan at around 1430 on 29 July.

Savo – Solomon Islands : According to a news source, residents on Savo in the Solomon Islands reported increased seismicity to authorities on 28 July. Two days later a team from the Geological Survey Division (GSD) and the National Disaster Management Office (NDMO) investigated the volcano. They saw steam-and-gas emissions rising from an area in the crater, possibly indicating an active fissure.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that seismicity at Semisopochnoi had increased in recent days. A notable increase at 0200 on 31 July prompted AVO to raise the Aviation Color Code to Orange and the Volcano Alert Level to Watch a few hours later. Additionally, increased infrasound recorded by local stations suggested low-level emissions. Weather clouds obscured satellite views, though a possible sulfur dioxide plume was detected. Steaming was visible in webcam images. Increased seismicity and elevated activity in infrasound data were recorded during 31 July-1 August, and multiple, discrete, energetic explosions were detected during 1-3 August. Weather clouds again obscured satellite views; steaming was visible in webcam views. Beginning at 1015 on 2 August the local networks recorded an explosion and an intense burst of seismic and acoustic tremor that lasted for about 15 minutes. A small ash cloud was visible in satellite images drifting 60 km N at altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. Ash emissions from the active vent in North Crater were visible in webcam views on the morning of 3 August.

Ulawun – New Britain (Papua New Guinea) : According to the Darwin VAAC, pilots observed ash plumes from Ulawun on 29 July and 3 August rising 3-3.4 km (10,000-11,000 ft) a.s.l. and drifting E and SSE, respectively. Weather clouds prevented satellite confirmation of the emissions.

Volcanos

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

Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 13-19 July ash plumes from Dukono rose to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted NW, N, NE, and ESE.

Ebeko – Paramushir Island (Russia) : According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 10-14 July produced ash plumes that rose as high as 3 km (10,000 ft) a.s.l. and drifted E. A thermal anomaly was identified in satellite images on 10 and 12 July.

Fuego – Guatemala : INSIVUMEH reported that 5-15 explosions per hour were recorded during 13-20 July at Fuego, generating ash plumes as high as 1.1 km above the crater rim and shock waves that often rattled buildings around the volcano. Ash plumes mostly drifted 10-20 km NW, W, and SW and caused daily ashfall 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), Finca Palo Verde, 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 100-400 m above the summit during 13-19 July.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that ash plumes from Karymsky were identified in satellite data drifting 80 km NW, NE, and ESE during 8-11 and 15 July. A thermal anomaly was visible during 8 and 10-13 July.

Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 14-20 July. Lava fountaining and overflows from the fifth vent were sometimes visible, and lava from the crater flowed in tubes as well as on the surface. Visible activity at the vent occasionally paused for various lengths of time. IMO warned of the potential for lapilli and scoria fallout within a 650 m radius of the active vent. Authorities warned of increased gas emissions hazards.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that daily white-and-gray plumes from Lewotolok rose as high as 1 km and drifted W, NW, NE, and E during 13-20 July. Rumbling was heard daily. Incandescent material was ejected as far as 1 km from the summit vent in various directions during 16-18 July.

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 remained active during 9-15 July. The SW rim lava-dome volume was an estimated 1.83 million cubic meters and continued to shed material down the flank. One pyroclastic flow traveled 1.1 km down the SW flank and as far as 1.5 km SE. Avalanches traveled a maximum of 1.5 km SE (58 times), 2 km SW (98 times), 1 km W (one time), and 700 m NW (three times). The volume of the summit lava dome was 2.796 million cubic meters.

Nevado del Ruiz – Colombia : On 21 July Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that seismicity at Nevado del Ruiz was generally characterized by higher number of earthquakes that had larger magnitudes than the previous week. Gas-and-steam emissions were sometimes visible in webcam images rising as high as 1.1 km above the summit and drifting WNW and WSW; these emissions sometimes contained ash. Episodes of drumbeat seismicity were recorded during 13-14 and 17 July, indicating ascent or growth of a lava dome in Arenas Crater.

Sangay – Ecuador : IG reported a high level of activity at Sangay during 13-20 July. Weather clouds and rain sometimes prevented visual and webcam observations of the volcano. Daily ash plumes were identified in satellite images by the Washington VAAC, rising between 900 m to as high as 5.4 km above the volcano and drifting W, SW, SE, and NE. Ashfall was reported in Barca and Guamote (40 km WNW) on 14 July and in Guamote on 19 July. Signals indicating lahars were recorded by the seismic network during 15-16 and 18-20 July.

Santa Maria – Guatemala : INSIVUMEH reported that during 13-20 July daily explosions at Santa María’s Santiaguito lava-dome complex generated ash plumes that rose as high as 1 km above the summit and drifted as far as 12 km SW and W. Collapses of blocky lava from Caliente dome sent avalanches down the SW and W flanks, often reaching the base, and caused minor ashfall mostly on the volcano’s flank. Ashfall was also reported in San Marcos (8 km SW) and Loma Linda Palajunoj (6 km WSW) during 14-15 and 19-20 July. On 15 July blocks of extruded lava formed a lava flow on the W flank that was 700 m long. Block-and-ash flows descended the W and NE flanks.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that unrest continued at Semisopochnoi during 13-20 July. Periods of low-level tremor and steam plumes from Mount Cerberus were occasionally recorded. Elevated surface temperatures at the N cone of Mount Cerberus were identified in satellite images during 13-14 July and robust steam-and-gas emissions were seen in webcam images. A plume with low amounts of sulfur dioxide drifting about 200 km N was identified in satellite data on 17 July. Sulfur dioxide emissions were also detected the next day.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 9-16 July.

Sinabung – Indonesia : Video taken on 13 July and posted on social media showed new vents on the upper W flank of Sinabung that were producing steam-and-ash emissions. PVMBG reported that white-and-gray plumes rose 100-300 m from the summit and drifted E and SE. During 14-18 June white plumes rose as high as 300 m. An eruptive event that began around 1850 on 19 July and lasted about 11 minutes produced an ash plume that rose 1 km and drifted ESE.

Whakaari/White Island-North Island (New Zealand) : GeoNet reported continuing unrest at Whakaari/White Island. During overflights of the island on 15 and 20 July scientists observed minor steam-and-gas activity around the 2019 Primary Crater lava domes and noted that the Main Crater area continues to fill with water. Other fumarolic vents remained active and unchanged. Overall, seismicity was at low levels during the previous few months, punctuated by a few notable events; a short-lived tremor episode was recorded on 2 June, discrete acoustic signals recorded during 18-20 June were associated with geysering in a new vent N of 2019 Crater, and a 15-minute low-frequency volcanic earthquake occurred on 30 June. Nighttime incandescence has persisted in webcam views since the 30 June earthquake.