The Weekly Volcanic Activity Report: April 10 - 16, 2024

New activity/unrest was reported for 8 volcanoes from April 10 to 16, 2024. During the same period, ongoing activity was reported for 12 volcanoes.

New activity/unrest

Awu, Sangihe Islands

3.689°N, 125.447°E | Summit elev. 1318 m

PVMBG reported that an increase in both deep and shallow volcanic earthquakes at Awu were recorded on 22 March and again during 10-15 April. Tiltmeter data from two stations recorded inflation during 1 March-16 April. The Alert Level was raised to 3 (on a scale of 1-4) at 1800 on 16 April and the public was warned to stay at least 5 km away from the crater’s center. PVMBG noted that elevated seismicity had been occurring periodically since July 2023.

Geological summary: The massive Gunung Awu stratovolcano occupies the northern end of Great Sangihe Island, the largest of the Sangihe arc. Deep valleys that form passageways for lahars dissect the flanks of the volcano, which was constructed within a 4.5-km-wide caldera. Powerful explosive eruptions in 1711, 1812, 1856, 1892, and 1966 produced devastating pyroclastic flows and lahars that caused more than 8000 cumulative fatalities. Awu contained a summit crater lake that was 1 km wide and 172 m deep in 1922, but was largely ejected during the 1966 eruption.

Etna, Sicily (Italy)

37.748°N, 14.999°E | Summit elev. 3357 m

INGV reported that at 2241 on 10 April a weak explosion at Etna’s Southeast Crater produced an ash emission that quickly dispersed based on webcam images. INGV issued a Volcano Observatory Notices for Aviation (VONA) on 12 and 16 April lowering the Aviation Color Code to Yellow and then Green, respectively.

Geological summary: Mount Etna, towering above Catania on the island of Sicily, has one of the world’s longest documented records of volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Fernandina, Isla Fernandina (Galapagos)

0.37°S, 91.55°W | Summit elev. 1476 m

Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that the eruption at Fernandina continued during 10-16 April. Daily thermal anomalies were identified in satellite images, though during 12-14 April they were characterized as slight. Sulfur dioxide emissions based on satellite data fluctuating between about 120 and 658 tons per day. Gas-and-steam emissions rose from the area where lava entered the ocean based on satellite images; the emissions decreased on 13 April suggesting that only a very small amount of lava was entering the ocean. A new lobe of lava to the W of the main flow was identified in satellite images during 15-16 February.

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.

Kavachi, Solomon Islands

8.991°S, 157.979°E | Summit elev. -20 m

Satellite data showed a roughly circular area of yellow-green discolored water that was about 2.9 km in diameter in the vicinity of the submarine Kavachi volcano on 9 April. A more diffuse plume expanded another ~5 km E. Weather clouds obscured views on 14 April.

Geological summary: Named for a sea-god of the Gatokae and Vangunu peoples, Kavachi is located in the Solomon Islands south of Vangunu Island. Sometimes referred to as Rejo te Kvachi (“Kavachi’s Oven”), this shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 1 km long many times since its first recorded eruption during 1939. Residents of the nearby islands of Vanguna and Nggatokae (Gatokae) reported “fire on the water” prior to 1939, a possible reference to earlier eruptions. The roughly conical edifice rises from water depths of 1.1-1.2 km on the north and greater depths to the SE. Frequent shallow submarine and occasional subaerial eruptions produce phreatomagmatic explosions that eject steam, ash, and incandescent bombs. On a number of occasions lava flows were observed on the ephemeral islands.

Kuchinoerabujima, Ryukyu Islands (Japan)

30.443°N, 130.217°E | Summit elev. 657 m

JMA reported that shallow volcanic earthquakes at Kuchinoerabujima had been frequent since the beginning of April, with most epicenters located near Furudake Crater, and some near Shindake Crater (just N of Furudake). Both the number and magnitude of the volcanic earthquakes increased and remained elevated. The Alert Level was raised to 3 (on a scale of 1-5) at 1200 on 13 April due to the increased seismicity. Visual observations during 10-12 April field visits indicated no changes to the craters nor to the geothermal area near the fissure on the W side of the Shindake. Sulfur dioxide gas emissions were at low levels. The public was warned that ejected blocks and pyroclastic flows may impact areas within 1 km of both craters and within 2 km of Shindake.

Geological summary: A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

Poas, Costa Rica

10.2°N, 84.233°W | Summit elev. 2697 m

OVSICORI-UNA reported continuing emissions and eruptive activity at Poás during 10-16 April. Vents on the nearly dry crater floor emitted plumes of gas and steam on 10 April and the number of phreatic events began to increase. Starting at around 0600 on 11 April ash was present in emissions rising from Boca C. The plumes rose 500 m and drifted SW and S and residents in Naranjo (17 km WSW), Palmares (27 km SW), and Atenas (32 km SW) reported a sulfur odor. Eruptive events were not detected in seismic or infrasound data on 13 April. A small explosion at 2025 on 14 April produced a pulse of incandescence and an ash emission that rose less than 300 m. Emissions containing diffuse ash continued at least through the morning of 15 April.

Geological summary: The broad vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the complex stratovolcano extends to the lower N flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, last erupted about 7,500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world’s most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since an eruption was reported in 1828. Eruptions often include geyser-like ejections of crater-lake water.

Ruang, Sangihe Islands

2.3°N, 125.37°E | Summit elev. 725 m

PVMBG reported that the number of deep volcanic earthquakes at Ruang increased each day during 10-15 April, with the total number significantly higher than from the entire month of March. During the morning of 16 April dense white plumes were visible rising 200-500 m above the summit and seismicity intensified. At 1000 on 16 April the Alert Level was raised to 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the crater.

A minor eruption began at around 1337 on 16 April. The Darwin VAAC noted that an ash plume was visible in a satellite image rising to 1.2 km (4,000 ft) a.s.l. and drifting SSW. At 1600 the Alert Level was raised to 3. According to a news article a larger eruption began at 2045 and ash plumes rose 2 km. The eruption intensified overnight during 16-17 April. The Darwin VAAC report that at 0230 on 17 April ash plumes rose to 9.1 km (30,000 ft) a.s.l. and drifted W; another plume at 0300 reached 12.2 km (40,000 ft) a.s.l. and detached from the summit. Ash plumes at a lower altitude, 4.6 km (15,000 ft) a.s.l., drifted WSW. At 0600 ash plumes rose to 13.7 km (45,000 ft) a.s.l. and drifted W and NW. The plume was detached from the summit by 0713. BNPB reported that 828 people evacuated and the communication network in Laingpatehi village was not operational. Photos showed incandescent material being ejected above the summit, incandescent material on the flanks, and dense ash plumes with lightning rising into dark, nighttime skies.

Geological summary: Ruang volcano is the southernmost volcano in the Sangihe Island arc, north of Sulawesi Island; it is not the better known Raung volcano on Java. The 4 x 5 km island volcano is across a narrow strait SW of the larger Tagulandang Island. The summit contains a crater partially filled by a lava dome initially emplaced in 1904. Explosive eruptions recorded since 1808 have often been accompanied by lava dome formation and pyroclastic flows that have damaged inhabited areas.

Taal, Luzon (Philippines)

14.0106°N, 120.9975°E, Summit elev. 311 m

PHIVOLCS reported that a phreatic eruption at Taal was recorded during 0511-0524 on 12 April based on seismic data, infrasound data, and visual observations. A steam plume rose 2.4 km and drifted SW. Four phreatic eruptions recorded during 0945-1522 produced steam plumes that rose 100-300 m. The events originated from a new vent on the SW side of Taal Main Crater and each lasted 1-13 minutes long. A phreatic event was recorded at 1013 on 13 April, lasted for four minutes, and generated a steam plume that rose 600 m and drifted WNW. Sulfur dioxide emissions that same day averaged 4,709 tonnes per day. Steam emissions during 14-15 April rose as high as 900 m and drifted WSW. The Alert Level remained at 1 (on a scale of 0-5), and PHIVOLCS reminded the public that the entire Taal Volcano Island was a Permanent Danger Zone (PDZ) and to take extra precaution around Main Crater and along the Daang Kastila fissure.

Geological summary: Taal is one of the most active volcanoes in the Philippines and has produced some powerful eruptions. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, with several submerged eruptive centers. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all observed eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones. Powerful pyroclastic flows and surges have caused many fatalities.

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 8-15 April with nighttime crater incandescence. An explosion at 2137 on 10 April produced an ash plume that rose 500 m above the crater rim and ejected large blocks 1.2 km from the vent. Sulfur dioxide emissions were extremely high, averaging 4,300 tons per day on 12 April. Very small eruptive events occasionally occurred during 12-15 April. 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.

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 4-11 April. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 6-8 and 11 April generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l. and drifted NW, NE, and E. A thermal anomaly was identified in satellite images on 6, 9, and 11 April; on other days either no activity was observed or weather conditions prevented 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.

Great Sitkin, Andreanof Islands (USA)

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

AVO reported that slow lava effusion in Great Sitkin’s summit crater was last confirmed in a 10 April radar satellite image with continuing inflation over the vent and advancement of the NW and E lava lobes. Effusion likely continued during 11-16 April. Seismicity was low with a few small daily earthquakes recorded by the seismic network. Weather clouds fully or partly obscured satellite and webcam views during some of the week. Possible weakly elevated surface temperatures were observed in satellite images during 15-16 April. 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.

Ibu, Halmahera

1.488°N, 127.63°E | Summit elev. 1325 m

PVMBG reported that Ibu continued to erupt during 10-16 April. White-and-gray ash plumes rose 200-2,000 m above the summit and drifted in multiple directions almost daily; white plumes rose 200-500 m above the summit and drifted SE, W, and NW on 15 April. The Alert Level remained at 2 (the second highest level on a four-level scale), with the public advised to stay outside of the 2 km hazard zone and 3.5 km away from the N area of the active crater.

Geological summary: The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, has contained several small crater lakes. The 1.2-km-wide outer crater is breached on the N, creating a steep-walled valley. A large cone grew ENE of the summit, and a smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. The first observed and recorded eruption was a small explosion from the summit crater in 1911. Eruptive activity began again in December 1998, producing a lava dome that eventually covered much of the floor of the inner summit crater along with ongoing explosive ash emissions.

Lewotobi, Flores Island

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

PVMBG reported that on 11 and 14 April white-and-gray plumes rose 100-500 m above the summit of Lewotobi’s Laki-laki volcano and drifted N and E. White plumes rose as high as 150 m above the summit and drifted in multiple directions during 10, 12-13, and 15-16 April. Incandescence at the summit was visible in a 14 April webcam image. An eruptive event was recorded on 15 April, though no emissions were observed, possibly due to weather conditions. The Alert Level remained at 2 (the second lowest level on a scale of 1-4) and the public was warned to stay outside of the exclusion zone, defined as a 2-km radius around Laki-laki crater, 3 km to the NNE, and 5 km on the NE flanks.

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

PVMBG reported that the eruption at Lewotolok continued during 10-16 April. White-and-gray ash plumes rose as high as 800 m above the summit and drifted in multiple directions almost every day; white emissions rose 400 m above the summit and drifted W and NW on 15 April. The Alert Level remained at 3 (on a scale of 1-4) and the residents of Lamawolo, Lamatokan, and Jontona were warned to stay 2 km away from the vent and 3 km away from the vent on the S and SE flanks.

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 10-16 April. White-and-gray ash plumes rose 200-600 m above the summit and drifted N and NW on 14 April. White steam-and-gas plumes rose 250-500 m above the summit and drifted in multiple directions on the other days. 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 5-11 April. Seismicity remained at high levels and was more intense than the previous week. The SW lava dome produced 103 lava avalanches that traveled as far as 1.8 km down the SW flank. One pyroclastic flow traveled 1.1 km SW down the upper part of the Bebeng drainage. Morphological changes to the SW lava dome were due to continuing effusion and collapses of material. 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.

Reykjanes, Reykjanes Peninsula

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

IMO reported that the eruption at a cone along the fissure within the Reykanes volcanic system continued during 10-15 April. Lava flowed short distance mostly S and the flows thickened near the crater. Inflation continued to be detected and gas emissions continued to drift downwind. Video posted by a news outlet showed lava roiling and spattering in the crater.

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.

Sabancaya, Peru

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

Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya continued at moderate levels during 8-14 April with a daily average of 44 explosions. Gas-and-ash plumes rose as high as 3 km above the summit and drifted less than 10 km E, SE, and S. Thermal anomalies over the lava dome in the summit crater were identified in satellite data. Slight inflation was detected near the Hualca Hualca sector (4 km N). Sulfur dioxide emissions were at moderate levels, 524 tons per day. The Alert Level remained at Orange (the third level on a four-color scale) and the public were warned to stay outside of a 12 km radius.

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.

Semeru, Eastern Java

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

PVMBG reported that eruptive activity continued at Semeru during 10-16 April. White-and-gray or occasionally white-to-brown ash plumes rose 300-1,000 m above the summit and drifted in multiple directions on most days. An eruptive event was recorded on 14 April but no emission was visible. 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 continuing eruptive activity at Sheveluch. A thermal anomaly was identified in satellite images during 6-9 and 11 April. A plume of resuspended ash drifted 140 km ESE on 11 April. 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.

References:

¹ Smithsonian Institution / US Geological Survey – Weekly Volcanic Activity Report – April 10 – 16, 2024 – Managing Editor: Sally Sennert.

Featured image credit: The Watchers

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