The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, these notices are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of eruptions during the week, but rather a summary of activity that meet selected criteria. Carefully reviewed, detailed reports are published monthly in the Bulletin of the Global Volcanism Network. The World Organization of Volcano Observatories (WOVO) website (https://wovo.iavceivolcano.org/) lists the regional volcano observatories that have the most authoritative data for many of these events.

Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that moderate eruptive activity continued at Fernandina during 20-26 March. Daily thermal anomalies were detected in satellite images. Sulfur dioxide (SO2) emissions identified in TROPOMI satellite data totaled 158 tons on 20 March, 720 tons on 24 March, and 790 tons during 25-26 March. Secretaría de Gestión de Riesgos (SGR) maintained the Alert Level at White (the lowest level on a four-color scale).

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) ,Secretaría de Gestión de Riesgos (SGR)

According to the Icelandic Meteorological Office (IMO), eruptive activity along the fissure that opened on 16 March began to stabilize on 20 March, with vents remaining in the same locations as previous days where cones had been built. The lava flows traveled S on top of older flows from the previous episodes in December 2023 and January-February 2024. Little or no change was observed at the flow fronts near Suðurstrandarvegur (the southern coast road) and Svartsengi. Lava began to flow into Melhólsnáma mine during 23-24 March, eventually filling it. Seismicity remained low. Early SO2 flux measurements from 17 March were up to 50 kg/s, but preliminary results from a more recent measurement indicated that the rate had decreased substantially. On the morning of 20 March, the National Land Survey of Iceland and the Institute of Natural History conducted aerial photography flights. Based on image analysis, an average discharge rate of 14.5 cubic meters per second during 17-20 March was estimated, and the new lava field was about 5.58 square kilometers with a volume of 20.9 million cubic meters. By 25 March the eruptive activity had decreased and possibly ceased at the smaller cones. The cones that remained active continued to grow, and the main lava flow extended south and bent westward. Seismicity and volcanic tremor gradually decreased. GPS monitoring continued to detect inflation at Svartsengi, but at a slower rate. High levels of SO2 were measured in Höfn and Grindavík over the past few days, and IMO warned of risk associated with gas emissions.

Sources: Almannavarnadeild ríkislögreglustjóra (National Commissioner of the Icelandic Police and Department of Civil Protection and Emergency Management),Icelandic Meteorological Office (IMO)

JMA reported ongoing eruptive activity at Minamidake Crater (Aira Caldera?s Sakurajima volcano) during 18-25 March. An explosion at 1952 on 18 March produced an ash plume that rose 1.2 km above the crater rim and drifted SE and ejected large blocks 800-1,100 m from the vent. Very small eruptions and nighttime incandescence were observed at the summit crater during other days of the report period. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 2 km away from both craters.

Source: Japan Meteorological Agency (JMA)

Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that Dukono continued to erupt during 20-26 March. Gray-and-white emissions rose as high as 450 m above the summit. The Alert Level remained at Level 2 (on a scale of 1?4), and the public was warned to remain outside of the 3-km exclusion zone.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

KVERT reported that moderate explosive activity was ongoing at Ebeko during 14-21 March. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), during 20-21 March explosions generated ash plumes that rose as high as 2.5 km (8,200 ft) a.s.l. and drifted SE. On other days the volcano was quiet, or weather clouds prevented satellite views. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are UTC; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

INSIVUMEH reported that eruptive activity continued at Fuego during 20-26 March. Explosions were recorded daily, averaging 3-12 per hour each day. The explosions generated ash and gas plumes that rose as high as 1 km above the crater rim and drifted as far as 30 km in multiple directions; ballistics occasionally fell as far as 2 km away. Frequent block avalanches caused by the explosions descended various drainages, including the Ceniza (SSW), Seca (W), Taniluyá (SW), Santa Teresa (W), and Las Lajas (SE), and sometimes reached vegetated areas. Incandescent material was ejected 100-300 m above the summit on 22 and 24 March. Weak rumbling sounds and shock waves were frequently reported. On 21 March ashfall was reported in Panimache (8 km SW), Morelia (9 km SW), and Santa Sofía (12 km SW).

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

AVO reported that slow lava effusion continued in Great Sitkin?s summit crater during 20-26 March. Weather clouds obscured or partly obscured satellite and webcam views during most of the week. A radar satellite image acquired during 19-20 March showed advancement of the active NW lava flow and uplift of the center of the lava dome above the vent. Seismicity was low and a few small earthquakes were recorded each day. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that white emissions rose as high as 100 m above the summit of Lewotobi Laki-laki during 20-26 March. Some rockfall events were detected by the seismic network. There were no visual observations of renewed lava effusion, and no reports of lava flow movement since 20 February. The Alert Level remained at Level 2 (on a scale of 1-4), and the public was warned to remain outside of the hazard zone, defined as a 2-km radius around the crater, the 3-km NNE sector expansion, and the 5-km NE sector expansion; both sector expansions extend from the established 2-km hazard radius.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported continuing activity at Lewotolok during 20-26 March. White-and-gray emissions were observed daily; plumes rose as high as 1 km above the summit. Seismicity included non-harmonic tremor episodes, frequent gas emission signals, and 6-18 daily eruption events. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 2-km away from the vent and 3-km away from the summit crater on the S and SE flank.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

PVMBG reported that eruptive activity at Marapi (on Sumatra) was ongoing during 20-26 March. White and gray ash plumes rose 200-500 m above the summit and drifted multiple directions on 20 and 24 March. White steam and gas plumes rose 200-250 m above the summit and drifted N, NE, and NW on 21 and 25 March. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 4.5 km away from the active crater.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

BPPTKG reported that the eruption at Merapi (on Java) continued during 15-21 March. Seismicity remained at high levels. The SW lava dome produced 59 lava avalanches that descended the SW flank as far as 1.8 km. Morphological changes to the SW lava dome caused by lava avalanches were identified in images from a drone survey on 21 March. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit, based on location.

Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG)

Servicio Geológico Colombiano?s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that eruptive activity at Nevado del Ruiz continued during 19-25 March. Seismicity associated with fluid movement decreased in both the number of events recorded and seismic energy released; most of these signals were associated with pulsating emissions of ash and gas. At 0516 on 22 March a seismic signal was associated with an ash emission that rose 1,100 m above the crater and drifted 1,400 m to the SW and W; this was the highest intensity signal this year. Several ash emissions were seen with a webcam. Seismicity associated with rock fracturing decreased in the number of events but increased in seismic energy released. These earthquakes at depths of 1-6 km below the summit were primarily located on the E flank, 3-5 km from the Arenas Crater, with additional events in other areas within 10 km of the crater. The largest event of the period was M 2.0 at 1217 on 24 March. Several thermal anomalies on the crater floor were identified in satellite data. The Alert Level remained at Yellow (the second level on a four-level scale), and the public was warned to stay out of the restricted areas around Arenas Crater.

Source: Servicio Geológico Colombiano (SGC)