Roundup of Global Volcanic Activity – New Activity for the Week 10 March 2021 – 16 March 2021
Bagana – Bougainville (Papua New Guinea) : Based on satellite and wind model data, the Darwin VAAC reported that on 10 March ash plumes from Bagana rose to 2.4 km (8,000 ft) a.s.l. and drifted NW and WNW.
Etna – Sicily (Italy) : INGV reported continuing episodes of lava fountaining at Etna’s Southeast Crater (SEC) on 9 and 12 March. The eleventh episode began with Strombolian activity at SEC observed at 1914 on 9 March. Just after midnight activity quickly intensified with lava fountaining and a large eruption plume that rose at least 9 km a.s.l. The plume drifted ENE and caused ash and lapilli to fall in Mascali (18 km E), Giarre (17 km ESE), and Fiumefreddo (19 km ENE). Lava reached an elevation of 1,800 m, also effusing from the flank of the S vent. Lava fountaining ceased at 0430 on 10 March and sporadic ash emissions continued until 0700. The twelfth episode began at 0630 on 12 March with Strombolian activity at SEC and ash emissions. The activity intensified at 0754 and lava overflowed the E part of SEC, traveling towards the Valle de Bove. Lava fountaining began at 0841, with jets up to 500 m, and an eruption plume rose 6 km a.s.l. and drifted E. Lava advanced to 2,800 m elevation and within another hour had reached 2,000 m elevation. At 0939 the plume had risen 9-10 km and had caused ashfall in Milo and Fornazzo (10 km E), Giarre, Santa Venerina (15 km SE), and Torre Archirafi (20 km ESE). Lava fountaining ceased at 1050, though weak Strombolian activity and ash emissions continued until 1115. The lava flow advanced as far as 1,700 m elevation and a second lava flow expanded SE on the W slope of the Valle del Bove, stopping at 3,000 m a.s.l.
Krysuvik-Trolladyngja – Iceland : IMO reported that seismicity in the Reykjanes Peninsula remained elevated with thousands of earthquakes recorded during 10-16 March, in the western part of the Krýsuvík-Trölladyngja volcanic system in the Fagradalsfjall fissure swarm area. About 16,500 earthquakes had been detected over the week. Some of the largest events, M 4.3-5.4 recorded during 10-12 and 14-15 March, were felt as far as Hvanneyri (97 km NNE of Grindavik), Hvolsvollur (110 km ESE of Grindavik), and Saudakrokur (250 NE of Grindavik). A few, short-lived pulses of tremor were also recorded. The magma intrusion continued to move SW along a fault between Keilir and Fagradalsfjall, and was as shallow as 1 km below the surface. GPS, satellite, and seismic data indicated that the intrusion had expanded S to Nátthaga, a valley just E of Borgarfjall and S of Fagradalsfjall, and was 3-5 km long. Ground fracturing was visible in the area above the intrusion. The Aviation colour Code for Krýsuvík remained at Orange.
Momotombo – Nicaragua : The Washington VAAC reported that on 14 March a possible ash emission was visible in webcam and satellite data just above Momotombo. Ash was not visible in a subsequent satellite image captured around six hours later.
Pacaya – Guatemala : INSIVUMEH and CONRED reported that pulses of moderate-to-strong Strombolian explosions at Pacaya’s Mackenney Crater were commonly recorded during 9-16 March. Frequent ash plumes rose as high as 2 km and drifted as far as 30 km W, SW, and S. On 10 March lapilli (2 mm to 6 cm in length) fell in El Caracol (3 km SW), and ash fell in El Patrocinio (about 5 km W) and likely in other areas downwind. Ash plumes caused daily ashfall in variable places during 11-16 March, including El Patrocinio, San José El Rodeo, the municipality of San Vicente Pacaya (5 km NW), San Francisco de Sales (5 km N), San José el Bejucal (4 km N), San Antonio el Pepinal (7 km N), Concepción El Cedro (9 km NNW), San José Calderas, and the municipalities of Amatitlán (12 km N), Villa Nueva (16 km N), and Mixco (30 km N). Lapilli as long as 2 cm fell in El Patrocinio, San José El Rodeo and Concepción El Cedro on 16 March. Strombolian explosions and periodic lava fountaining ejected incandescent material as high as 800 m above the summit; tephra fell within a 500 m radius of Mackenney Crater. Explosions and ash emissions also rose from fissures on the S flank, 300 m below Mackenney Crater. The lava flow on the S flank had two branches and was 1 km on 10 March, but had lengthened to 1.8 km by 16 March. Block avalanches from the summit traveled down the S flank.
San Cristobal – Nicaragua : SINAPRED reported that a series of five explosions at San Cristóbal were recorded during 1306-1332 on 9 March. The strongest explosion, at 1325, produced an ash plume that rose 800 m above the crater rim. Ashfall as deep as 2 mm was reported in El Viejo (19 km WSW), Chinandega (16 km SW), and Chichigalapa (16 km S); ash also fell in other communities downwind including Las Grecias, La Mora, and La Bolsa.
Semisopochnoi – Aleutian Islands (USA) : On 12 March AVO reported that although no ash plumes were observed at Semisopochnoi and nothing was detected in regional infrasound data during the previous week, ash deposits within Mount Cerberus’s N crater and extending 1.5 km on the flank were identified in satellite data. The Aviation colour Code and the Volcano Alert Level remained at Yellow/Advisory, respectively.
Taal – Luzon (Philippines) : PHIVOLCS reported that during 10-13 March there were around 51-55 volcanic earthquakes recorded daily at Taal, and about 23-49 periods of volcanic tremor with variable durations. One hybrid earthquake was recorded during 11-12 March. Diffuse steam plumes from fumarolic vents in Main Crater rose only 5 m. Sulfur dioxide emissions were 1,327 tonnes per day on 10 March, and fluctuated between 518 and 795 tonnes per day through 14 March. At 1411 on 12 March a short-lived (2.5 minutes) burst of steam-rich gas from Main Crater generated white plumes that rose 400-500 m. Diffuse steam plumes rose 50 m above fumarolic vents on the inner N and E walls during the rest of the day. The number of volcanic earthquakes per day rose to 74 during 13-14 March and to 252 during 15-16 March. Episodes of tremor persisted, with 17-46 periods recorded per day. Five hybrid events were detected during 14-15 March. An episode of high-temperature gas upwelling to the crater lake’s surface occurred during 1830-2045 on 14 March. Sulfur dioxide emissions were 1,216 tonnes per day on 15 March. Steam emissions rose 10 km during 15-16 March. The seismic network recorded 42 volcanic earthquakes and 34 periods of tremor. The Alert Level for Taal remained at 2 (on a scale of 0-5). PHIVOLCS strongly recommended no entry onto the island, and access to the Main Crater and Daang Kastila fissure (along the walking trail) was strictly prohibited.
Veniaminof – United States : AVO reported that the eruption at Veniaminof continued during 9-16 March. Ash emissions rose to 2.1-3 km (7,000-10,000 ft) a.s.l. and drifted 200 km NE and SE during 9-10 March. Explosions and ash emissions declined to lower levels the rest of the week, though new ash deposits within the caldera, and as far as 10 km SE, were sometimes identified in satellite images. Lava continued to effuse under the intra-caldera glacier in an area on the flank about 1 km E of the cone’s summit. Elevated surface temperatures over this area were identified in a satellite images during most days, along with steam plumes and a broadening collapse pit in the ice from melting around the eruption site. Data from local seismic stations were back online by 12 March and showed elevated seismicity and tremor through 15 March. Steam-and-has plumes were identified in satellite images during 15-16 March. The Volcano Alert Level remained at Watch and the Aviation colour Code remained at Orange.
