The Weekly Volcanic Activity Report: March 20 - 26, 2024

New activity/unrest was reported for 2 volcanoes from March 20 – 26, 2024. During the same period, ongoing activity was reported for 17 volcanoes.

New activity/unrest: Fernandina, Isla Fernandina (Galapagos) | Reykjanes, Reykjanes Peninsula.

New activity/unrest

Fernandina, Isla Fernandina (Galapagos)

0.37°S, 91.55°W | Summit elev. 1476 m

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).

Geological summary: Fernandina, the most active of Galápagos volcanoes and the one closest to the Galápagos mantle plume, is a basaltic shield volcano with a deep 5 x 6.5 km summit caldera. The volcano displays the classic “overturned soup bowl” profile of Galápagos shield volcanoes. Its caldera is elongated in a NW-SE direction and formed during several episodes of collapse. Circumferential fissures surround the caldera and were instrumental in growth of the volcano. Reporting has been poor in this uninhabited western end of the archipelago, and even a 1981 eruption was not witnessed at the time. In 1968 the caldera floor dropped 350 m following a major explosive eruption. Subsequent eruptions, mostly from vents located on or near the caldera boundary faults, have produced lava flows inside the caldera as well as those in 1995 that reached the coast from a SW-flank vent. Collapse of a nearly 1 km3 section of the east caldera wall during an eruption in 1988 produced a debris-avalanche deposit that covered much of the caldera floor and absorbed the caldera lake.

Reykjanes, Reykjanes Peninsula

63.817°N, 22.717°W | Summit elev. 140 m

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.

Geological summary: The Reykjanes volcanic system at the SW tip of the Reykjanes Peninsula, where the Mid-Atlantic Ridge rises above sea level, comprises a broad area of postglacial basaltic crater rows and small shield volcanoes. The submarine Reykjaneshryggur volcanic system is contiguous with and is considered part of the Reykjanes volcanic system, which is the westernmost of a series of four closely-spaced en-echelon fissure systems that extend diagonally across the Reykjanes Peninsula. Most of the subaerial part of the system (also known as the Reykjanes/Svartsengi volcanic system) is covered by Holocene lavas. Subaerial eruptions have occurred in historical time during the 13th century at several locations on the NE-SW-trending fissure system, and numerous submarine eruptions dating back to the 12th century have been observed during historical time, some of which have formed ephemeral islands. Basaltic rocks of probable Holocene age have been recovered during dredging operations, and tephra deposits from earlier Holocene eruptions are preserved on the nearby Reykjanes Peninsula.

Ongoing activity

Aira, Kyushu (Japan)

31.5772°N, 130.6589°E | Summit elev. 1117 m

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.

Geological summary: The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan’s most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim and built an island that was joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4,850 years ago, after which eruptions took place at Minamidake. Frequent eruptions since the 8th century have deposited ash on the city of Kagoshima, located across Kagoshima Bay only 8 km from the summit. The largest recorded eruption took place during 1471-76.

Dukono, Halmahera

1.6992°N, 127.8783°E | Summit elev. 1273 m

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.

Geological summary: Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia’s most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, have occurred since 1933. During a major eruption in 1550 CE, a lava flow filled in the strait between Halmahera and the N-flank Gunung Mamuya cone. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

Ebeko, Paramushir Island (Russia)

50.686°N, 156.014°E | Summit elev. 1103 m

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.

Geological summary: The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Fuego, South-Central Guatemala

14.473°N, 90.88°W | Summit elev. 3763 m

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).

Geological summary: Volcán Fuego, one of Central America’s most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala’s former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

Great Sitkin, Andreanof Islands (USA)

52.076°N, 176.13°W | Summit elev. 1740 m

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).

Geological summary: The Great Sitkin volcano forms much of the northern side of Great Sitkin Island. A younger volcano capped by a small, 0.8 x 1.2 km ice-filled summit caldera was constructed within a large late-Pleistocene or early Holocene scarp formed by massive edifice failure that truncated an older edifice and produced a submarine debris avalanche. Deposits from this and an even older debris avalanche from a source to the south cover a broad area of the ocean floor north of the volcano. The summit lies along the eastern rim of the younger collapse scarp. Deposits from an earlier caldera-forming eruption of unknown age cover the flanks of the island to a depth up to 6 m. The small younger caldera was partially filled by lava domes emplaced in 1945 and 1974, and five small older flank lava domes, two of which lie on the coastline, were constructed along northwest- and NNW-trending lines. Hot springs, mud pots, and fumaroles occur near the head of Big Fox Creek, south of the volcano. Eruptions have been recorded since the late-19th century.

Lewotobi, Flores Island

8.542°S, 122.775°E | Summit elev. 1703 m

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.

Geological summary: The Lewotobi edifice in eastern Flores Island is composed of the two adjacent Lewotobi Laki-laki and Lewotobi Perempuan stratovolcanoes (the “husband and wife”). Their summits are less than 2 km apart along a NW-SE line. The conical Laki-laki to the NW has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has had observed eruptions in 1921 and 1935. Small lava domes have grown during the 20th century in both of the summit craters, which are open to the north. A prominent cone, Iliwokar, occurs on the E flank of Perampuan.

Lewotolok | Lembata Island

8.274°S, 123.508°E | Summit elev. 1431 m

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.

Geological summary: The Lewotolok (or Lewotolo) stratovolcano occupies the eastern end of an elongated peninsula extending north into the Flores Sea, connected to Lembata (formerly Lomblen) Island by a narrow isthmus. It is symmetrical when viewed from the north and east. A small cone with a 130-m-wide crater constructed at the SE side of a larger crater forms the volcano’s high point. Many lava flows have reached the coastline. Eruptions recorded since 1660 have consisted of explosive activity from the summit crater.

Marapi, Central Sumatra

0.38°S, 100.474°E | Summit elev. 2885 m

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.

Geological summary: Gunung Marapi, not to be confused with the better-known Merapi volcano on Java, is Sumatra’s most active volcano. This massive complex stratovolcano rises 2,000 m above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera. The summit craters are located along an ENE-WSW line, with volcanism migrating to the west. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no lava flows outside the summit craters have been reported in historical time.

Merapi, Central Java

7.54°S, 110.446°E | Summit elev. 2910 m

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.

Geological summary: Merapi, one of Indonesia’s most active volcanoes, lies in one of the world’s most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequent growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities.

Nevado del Ruiz, Colombia

4.892°N, 75.324°W | Summit elev. 5279 m

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.

Geological summary: Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers more than 200 km2. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America’s deadliest eruption.

Nyiragongo, DR Congo

1.52°S, 29.25°E | Summit elev. 3470 m

Observatoire Volcanologique de Goma (OVG) reported that the sulfur dioxide (SO2) flux at Nyiragongo decreased slightly but remained at moderate levels during 18-23 March. The Munigi station measured a small increase in carbon dioxide (CO2) concentrations from fractures in the S area. Additionally, CO2 concentrations in the “mazuku”, or lowland areas located in the W area of the city of Goma, remained lethal. The Alert Level remained at Yellow.

Geological summary: The Nyiragongo stratovolcano contained a lava lake in its deep summit crater that was active for half a century before draining catastrophically through its outer flanks in 1977. The steep slopes contrast to the low profile of its neighboring shield volcano, Nyamuragira. Benches in the steep-walled, 1.2-km-wide summit crater mark levels of former lava lakes, which have been observed since the late-19th century. Two older stratovolcanoes, Baruta and Shaheru, are partially overlapped by Nyiragongo on the north and south. About 100 cones are located primarily along radial fissures south of Shaheru, east of the summit, and along a NE-SW zone extending as far as Lake Kivu. Many cones are buried by voluminous lava flows that extend long distances down the flanks, which is characterized by the eruption of foiditic rocks. The extremely fluid 1977 lava flows caused many fatalities, as did lava flows that inundated portions of the major city of Goma in January 2002.

Popocatepetl, Mexico

19.023°N, 98.622°W | Summit elev. 5393 m

Centro Nacional de Prevención de Desastres (CENAPRED) reported that eruptive activity continued at Popocatépetl during 20-26 March. Daily activity consisted of 14-69 long-period (LP) events that were accompanied by emissions of gas, steam, and small quantities of ash. Additionally, high-frequency and variable amplitude episodes of tremor were registered; duration of episodes ranged from approximately 2.9 to 17.6 hours per day. Continuous gas, steam, and sometimes ash emissions were observed during the mornings; plumes dispersed towards the NE and ENE. Centro Nacional de Comunicación y Operación de Protección Civil (CENACOM) reported light ashfall in multiple municipalities within the state of Puebla during 20-26 March, and within the state of Tlaxcala during 25-26 March.

Geological summary: Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America’s 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.

Sabancaya, Peru

15.787°S, 71.857°W | Summit elev. 5960 m

Instituto Geofísico del Perú (IGP) reported that moderate levels of eruptive activity continued at Sabancaya during 20-26 March. The monitoring network recorded a range of 5-30 explosions per day. Explosions generated ash plumes that rose as high as 1.1 km above the summit crater and drifted less than 10 km in multiple directions; plume heights were not visible during 24-26 March. Seismic signals associated with the movement of magma and gases were registered; totaled counts ranged between 16 and 76 events per day. Thermal anomalies over the lava dome in the summit crater were identified in satellite images almost daily but were not detected during the night of 22 March. Deformation monitoring data indicated continued slight inflation near the Hualca Hualca sector (4 km N). The Alert Level remained at Orange (the third level on a four-color scale) and the public was reminded to stay at least 12 km away from the summit crater in all directions.

Geological summary: Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning “tongue of fire” in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.

Santa Maria, Southwestern Guatemala

14.757°N, 91.552°W | Summit elev. 3745 m

INSIVUMEH reported that eruptive activity continued at Santa Maria’s Santiaguito lava dome complex during 20-26 March with a lava extrusion and avalanches at the Caliente dome. Incandescence from the dome was visible during most nights and early mornings, and occasional incandescence was also present along the upper WSW flank lava flow. Daily explosions generated ash, gas, and steam plumes that rose as high as 900 m above the summit and drifted multiple directions on most days, and on 20 March rose 2.2 km above the summit. The explosions occurred at rates between 1 and 7 per hour that generated block avalanches on the dome’s flanks and occasional short pyroclastic flows that descended multiple flanks. Sometimes the block avalanches were accompanied by rumbling sounds. On 21 and 22 March ashfall was reported in Loma Linda (7 km W), San Marcos Palajunoj (8 km SW) and other communities in this area; ash caused hazy conditions around the volcano on 24 and 25 March.

Geological summary: Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing E towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Semeru, Eastern Java

8.108°S, 112.922°E | Summit elev. 3657 m

PVMBG reported that eruptive activity continued at Semeru during 20-26 March. During the week, 14 eruptive events were recorded by the seismic network, and ash plumes rose 500-1,200 m above the summit and drifted in multiple directions. During 20 and 23-24 March white and gray emissions rose 50-200 m above the summit and drifted multiple directions. On 25 March white emissions rose 100-200 m above the summit and drifted SW, W, and NW. The Alert Level remained at 3 (the third highest level on a scale of 1-4). The public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17 km from the summit, and to avoid other drainages including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

Geological summary: Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.

Sheveluch, Central Kamchatka (Russia)

56.653°N, 161.36°E | Summit elev. 3283 m

KVERT reported that eruptive activity at Sheveluch continued with a thermal anomaly identified in satellite images during 17-21 March. Strong gas and steam emissions were observed at the Karan dome. On 21 March plumes of resuspended ash extended 65 km to the SE. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka’s largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Suwanosejima, Ryukyu Islands (Japan)

29.638°N, 129.714°E | Summit elev. 796 m

Japan Meteorological Agency (JMA) reported that the eruption at Suwanosejima’s Ontake Crater continued during 20-26 March. Crater incandescence was observed nightly in infrared camera images. A total of seven explosions were registered by the seismic network; resulting ash plumes rose up to 1.3 km above the crater rim before drifting N and SE and ejected large ballistic projectiles (20-30 cm in diameter) as far as 600 m away from the center of the crater. The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1-km away from the crater.

Geological summary: The 8-km-long island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two active summit craters. The summit is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. One of Japan’s most frequently active volcanoes, it was in a state of intermittent Strombolian activity from Otake, the NE summit crater, between 1949 and 1996, after which periods of inactivity lengthened. The largest recorded eruption took place in 1813-14, when thick scoria deposits covered residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed, forming a large debris avalanche and creating an open collapse scarp extending to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

References:

¹ Smithsonian Institution / US Geological Survey – Weekly Volcanic Activity Report March 20 – 26, 2024 – Managing Editor: Sally Sennert – Written by JoAnna G. Marlow.

Featured image credit: TW

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