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

Cleveland – Chuginadak Island (USA) : AVO reported that on 10 March an earthquake at Cleveland was large enough to be recorded by seismometers 100 km away on Umnak Island. On 17 March volcanic gas emissions increased and elevated surface temperatures were identified in satellite images. The Aviation colour Code was raised to Yellow and the Volcano Alert Level was raised to Advisory.

Etna – Sicily (Italy) : INGV reported continuing episodes of lava fountaining at Etna’s Southeast Crater (SEC) on 15, 17, and 19 March, though weather conditions often prevented visual observations. Strombolian activity at SEC began at 2110 on 14 March and turned into lava fountaining at 0048 on 15 March. Lava traveled towards the Valle de Bove and an eruption plume drifted E. Lava fountaining ceased by 0343 and only weak Strombolian activity followed. The lava flows continued to advance. Weak Strombolian activity at SEC on 17 March began to intensify at 0155 and changed into lava fountaining at 0319. An eruption plume drifted SE and lava flow advanced. Fountaining activity ceased at 0717 and was followed by explosive activity. By 1859 the lava flows had reached 2,200 m elevation. Explosions at SEC and the lava flow in the Valle de Bove were visible at 2142 on 18 March when the weather conditions allowed for partial visibility of the summit. Explosive activity at SEC was visible at 0734 on 19 March. The activity intensified at 0915 and ash emissions were visible. Lava fountaining started at 0935 and an ash plume drifted ENE. Lava fountaining activity ceased at 1136 and changed to Strombolian activity which gradually decreased; by 1350 only sporadic explosions were visible along with minor ash emissions. Lava flows were noted late in the morning.

Krysuvik-Trolladyngja – Iceland : IMO reported that a small eruption in the western part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, began at around 2045 on 19 March. The eruption was first visible in webcam images and confirmed by satellite data, and an orange glow in clouds on the horizon was seen from Reykjanesbaer and Grindavík (10 km SW). The Aviation colour Code was raised to Red. Reykjanesbraut, the main road from the capital region to Reykjanesbaer and the international airport at Keflavík, was closed. A fissure, 500-700 m long, had opened on a slope in the Geldingadalur valley about 4.7 km N of the coast and just off the SE flank of Fagradalsfjall mountain. Small lava fountains rose as high as 100 m above the fissure, and by 1110 on 20 March, the lava had covered an area less than 1 square kilometer and was approximately 500 m across. The extrusion rate was an estimated 5 cubic meters per second. The Aviation colour Code was lowered to Orange because there was little to no ash production that would affect aircraft. Reykjanesbraut reopened, but Sudurstrandarvegur, the road along the S coastline, was closed between Grindavík and Thorlakshofn. The eruption continued during 21-23 March with a consistent extrusion rate. About three cones had formed along the fissure; the tallest and widest was situated at the higher part of the fissure. Lava flows, mainly from the largest cone, fanned out to the NW, W, and SW, and also flowed S and fanned out to the E. Spatter was ejected above the cones. Video captured by visitors showed parts of the largest cone collapsing and rebuilding. 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. IMO noted that through the night of 22-23 March night sulfur dioxide levels in Reykjavík had increased, though not to unsafe levels.

Pacaya – Guatemala : INSIVUMEH reported periods of intense activity at Pacaya’s Mackenney Crater during 17-18 March. Explosions produced dense ash plumes that rose 500-1,000 m above the crater rim and drifted 25-30 km S, SW, W, NW, and N. Incandescent material was ejected 300-500 m above the crater and fell within a 600 m radius of the crater. Lava flows on the S flank were 1.5 km long and set fire to vegetation at the advancing edge. Two new lava flows were visible; one traveled 400 m E and the other traveled 500 m S. Ashfall was reported in El Rodeo (4 km WSW), Patrocinio (about 5 km W), El Cedro (9 km NNW), San Francisco de Sales (5 km N), Amatitlán (12 km N), and Villa Nueva (16 km N). Strong explosions during 21-23 March generated dense ash plumes that rose as high as 1.5 km above the summit. The plumes drifted 25-30 km NE, E, SE, and S, causing ashfall in Los Llanos, Los Pocitos (5 km S), Los Dolores (6 km SE), El Rodeo, Patrocinio, Mesías Alta and Mesías Baja, and Santa Elena Barillas (6 km ENE). Incandescent material was ejected 500 m above the crater and fell within 300-600 m of the crater. A lava flow on the SW flank was 1.5 km long, a flow on the S flank was 300 m long, and the E-flank lava flow had lengthened to 500 m. On 23 March ash plumes drifted 50 km NW, N, and NE, causing ashfall in Pepinal San Francisco de Sales, Los Pocitos, Los Dolores, Mesías Altas and Mesías Bajas, Santa Elena Barillas, Villa Nueva, and in the capital of Guatemala City (25-30 km NNE). Ash fell at Guatemala’s international airport, Aeropuerto Internacional La Aurora, 50 km N of Pacaya, causing the airport to close. Soldiers swept ash off of the runway and incoming flights were diverted to El Salvador.

San Cristobal – Nicaragua : The Washington VAAC reported that on 19 March a notable ash cloud from San Cristóbal rose at least to 12.2 km (40,500 ft) a.s.l. and drifted over 80 km ENE based on satellite data, ash dispersion models, and weather models.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that satellite data showed minor ash deposits on Semisopochnoi’s flanks and a possible gas cloud on 14 March. Two small explosions on 19 March, at 0350 and 0534, were recorded by regional infrasound sensors and prompted AVO to raise the Aviation colour Code and the Volcano Alert Level to Orange and Watch, respectively. A small explosion at 0230 on 21 March was followed by a series of smaller explosions. A volcanic gas cloud was visible in satellite data during the previous day. Three small explosions were detected during 22-23 March, though 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.

Taal – Luzon (Philippines) : PHIVOLCS reported that at Taal during 16-23 March there were 36-193 daily volcanic earthquakes and 27-156 daily periods of volcanic tremor with variable durations (1-15 minutes). Three hybrid earthquakes were recorded each day on 18 and 19 March. Diffuse steam plumes from fumarolic vents in Main Crater rose as high as 100 m. Daily measurements of sulfur dioxide emissions were 603-1,184 tonnes per day. The Alert Level 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 the eruption at Veniaminof continued during 17-23 March. Low surface temperatures were visible in satellite images along with steam-and-gas plumes. Low-level tremor was recorded in local seismic data. During the morning of 21 March small explosions were identified using seismic data and infrasound sensors in Chignik Lagoon. A volcanic gas cloud drifted SE at or below 1.5 km (5,000 ft) a.s.l. Small explosions were detected again during 21-23 March. Sulfur dioxide plumes were identified in satellite data. Minor ash emissions rose hundreds of meters and rapidly dissipated, though on 23 March a pilot saw an ash plume rise to 3 km (10,000 ft) a.s.l. Satellite data during 22-23 March showed highly elevated surface temperatures and subsidence of the glacial ice over the flank vent where lava was erupting. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.

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