The Weekly Volcanic Activity Report: February 14 - 20, 2024

New activity/unrest was reported for 2 volcanoes from February 14 to 20, 2024. During the same period, ongoing activity was reported for 20 volcanoes.

New activity/unrest: Gareloi, Aleutian Islands (USA) | Reykjanes, Reykjanes Peninsula.

New activity/unrest

Gareloi, Aleutian Islands (USA)

51.79°N, 178.794°W | Summit elev. 1573 m

AVO reported that unrest continued at Gareloi during 14-20 February. Seismicity remained elevated and was characterized by volcanic earthquakes and semi-continuous tremor, though after 16 February levels began to decline and only periods of seismic tremor were reported. Minor steaming was identified in webcam and satellite images on 14 February. The Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale) and the Aviation Color Code remained at Yellow (the second lowest color on a four-color scale).

Geological summary: The 8 x 10 km Gareloi Island, the northernmost volcano of the Delarof Group at the western end of the Andreanof Islands, consists of a stratovolcano with two summits and a prominent SE-trending fissure. The fissure was formed during an eruption in 1929 and extends from the southern summit to the sea. Steep sea cliffs that are cut into rocks of an older, eroded center are found on the SW coast, and submarine deposits of three debris avalanches produced by edifice collapse are found offshore. Young lava flows cover the older volcano from the summit to the coast along three broad axes trending NW, ENE, and S. The 1929 eruption originated from 13 craters along a 4-km-long fissure. Phreatic explosions were followed by the ejection of glassy pumice, lapilli, scoria, and older blocks, as well as by the emission of four short, steep lava flows, one of which reached the SE coast.

Reykjanes, Reykjanes Peninsula

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

A fissure eruption in the area between Sundhnúkur and Stóra Skógfell on the Reykjanes peninsula began at 0602 on 8 February after around 30 minutes of intense seismic activity, prompting IMO to raise the Aviation Color Code to Red (the highest level on a four-color scale). During a helicopter overflight the location of the fissure was confirmed to be near the 18 December 2023 fissure, less than 1 km NE of Sylingarfell. The fissure lengthened to 3 km N-S, with lava flows moving W and E. Lava fountains along the fissure rose 50-80 m high and a volcanic plume mainly comprised of gas and steam rose to 3 km. IMO lowered the Aviation Color Code to Orange at 0626, noting that ash was not present in the plume. Tephra fall was reported in parts of Grindavík, 3-5 km S of the fissure. Visitors to the Blue Lagoon were evacuated; there were no residents in Grindavík due to previous evacuations.

Deformation in the dike area had significantly decreased by noon, and the intensity of the eruption had also declined, with only three active craters along the fissure. Emissions from the fissure drifted SW. Lava advanced N, curving around the Stóra Skógfell cones and branching to the SW. The SW branch advanced at a rate of about 500 m per hour, according to a news article, and flowed over both Grindavíkurvegur (Road 43) and Bláalóns-road, at the exit for the Blue Lagoon, at around noon. Lava also advanced over the pipeline that supplied hot water to Svartsengi. Power lines were also affected by the flows, though electricity was restored later that day.

Minor explosive activity generated from the interaction of magma and ground water began during 1300-1400 on 8 February and produced dark plumes rising as high as 2.5 km from the middle of the fissure and drifting S. The explosive activity was mainly over by 1715 and the intensity of the eruption continued to decrease. Deformation was no longer being detected, suggesting that magma was no longer ascending at the same pressure as at the beginning of the eruption. Seismic activity significantly decreased after the onset of the eruption and remained at low levels with only about 20 small earthquakes recorded during 0800-1715. Lava flowed as far as 4.5 km W of the fissure. Activity and tremor levels fluctuated at low levels during the evening of the 8th and further decreased during 0700-0800 on 9 February, with only two craters active. No fountains were visible mid-morning; a drone overflight at around noon confirmed that activity had ceased. IMO lowered the Aviation Color Code to Yellow at 1713.

Deformation data suggested that inflation began again after the eruption had ended; model calculations showed that during 9-14 February an estimated two million cubic meters of magma had accumulated beneath the Svartsengi area, or about 20% of the volume of magma that had accumulated before the 8 February eruption. The hot water pipeline was restored by 12 February and the Blue Lagoon reopened to visitors on 16 February.

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 12-19 February with nighttime crater incandescence. Sulfur dioxide emissions averaged 1,400 tons per day on 20 December. An explosion at 0659 on 14 February generated an ash plume that rose 2 km above the crater rim and drifted N, and ejected blocks 300-500 m away from the vent. A larger explosion at 1833 on 14 February produced an ash plume that rose as high as 5 km above the summit that drifted E and NE and ejected large blocks as far as 1.3 km from the vent. Ash plumes had not risen that high since an explosion at 0538 on 9 August 2020. A large amount of ashfall completely covered roadways in some parts of the N part of the island based on 15 February field observations. Residents reported ashfall in Kagoshima, Aira, Kirishima, Kanoya, Soo, and parts of Miyazaki Prefecture. Eruptive events at 2220 on 16 February, and 1523, 1556, 1631, and 2359 on 17 February, generated ash plumes that rose 1-1.3 km above the summit and drifted E and SE. 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

PVMBG reported that the eruption at Dukono was ongoing during 14-20 February. Gray-and-white ash plumes rose 150-750 m above the summit and drifted S, W, and NW on most days; emissions were not observed on 16 February. The Alert Level remained at Level 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-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 8-15 February. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 8 and 11-15 February generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l and drifted E. A thermal anomaly was identified in satellite images on 15 February. 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.

El Misti, Peru

16.294°S, 71.409°W | Summit elev. 5822 m

Instituto Geofísico del Perú (IGP) reported that a lahar descended the SE flank of El Misti at 1905 on 20 February. The public was warned to stay away from drainages and roads on that flank.

Geological summary: El Misti is a symmetrical andesitic stratovolcano with nested summit craters that towers above the city of Arequipa, Peru. The modern symmetrical cone, constructed within a small 1.5 x 2 km wide summit caldera that formed between about 13,700 and 11,300 years ago, caps older Pleistocene volcanoes that underwent caldera collapse about 50,000 years ago. A large scoria cone has grown with the 830-m-wide outer summit crater. At least 20 tephra-fall deposits and numerous pyroclastic-flow deposits have been documented during the past 50,000 years, including a pyroclastic flow that traveled 12 km to the south about 2000 years ago. The most recent activity has been dominantly pyroclastic, and strong winds have formed a parabolic dune field of volcanic ash extending up to 20 km downwind. An eruption in the 15th century affected nearby Inca inhabitants. Some reports of historical eruptions may represent increased fumarolic activity.

Great Sitkin, Andreanof Islands (USA)

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

AVO reported that slow lava effusion likely continued at Great Sitkin during 13-20 February with growth concentrated at the center of the flow in the summit crater. Steam emissions were visible in satellite and webcam images during 14-15 February. A 15 February radar image showed inflation near the summit crater vent and a new lobe of lava advancing NW. A few small volcanic earthquakes were recorded by the seismic network on most days. Weather clouds obscured satellite and webcam views during most of the week. 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.

Kavachi, Solomon Islands

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

Satellite data showed distinct yellow-green discolored water in the vicinity of the submarine Kavachi volcano on 14 and 19 February. The discolored water extended 15-20 km SE and E.

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.

Lewotobi, Flores Island

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

PVMBG reported that the eruption at Lewotobi’s Laki-laki volcano was ongoing during 13-20 February. The lava flow on the NE flank continued to be active, advancing 100 m during 3-20 February to a total length of 4.2 km. A drone overflight on 20 February confirmed the position of the end of the lava flow. White steam-and-gas plumes were visible during 13, 15, 17, and 19-20 February rising as high as 100 m above the summit and drifting N, NE, and W; no emissions were observed on 14 February. White-and-gray ash plumes rose as high as 600 m above the summit on 16 and 18 February and drifted N and NE. According to a news article, all evacuees had returned to their homes. The Alert Level remained at 3 (the second highest level on a scale of 1-4) and the public was warned to stay outside of the exclusion zone, defined as a 3-km radius around Laki-laki crater, 4 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 31 January-6 February. White gas-and-steam plumes rose as high as 700 m above the summit and drifted NW, E, and SE during 14-19 February. A dense white-and-gray ash plume rose 1 km above the summit and drifted SE at 1639 on 19 February according to a news report. Emissions were not visible on 20 February. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay at least 2 km away from the summit crater.

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 14-20 February. White-and-gray ash plumes rose 200-900 m above them summit and drifted in multiple directions during 14-15, 18, and 20 February. White steam-and-gas plumes rose 400 m and drifted SW, W, and NE on 17 February; no emissions were observed on 16 and 19 February. 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 9-15 February. Seismicity remained at high levels. The SW lava dome produced 189 lava avalanches, three times the number from the previous week, that descended the S and SW flanks; two traveled S as far as 1.4 km down the upper part of the Boyong drainage and 187 traveled SW as far as 1.7 km down the upper part of the Bebeng drainage. Two pyroclastic flows descended the Bebeng drainage, traveling as far as 1.5 km. Morphological changes to the SW lava dome identified in webcam images and during a 15 February drone overflight were due to continuing effusion and collapses of material. The highest temperature on the dome was 254.3 degrees Celsius, lower than the previous highest temperature. 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 at moderate levels during 13-19 February. Seismic events indicating rock fracturing increased in number compared to the previous week. These events were located in areas up to 7 km in various directions from Arenas Crater at depths of 1-8 km. The largest earthquake, a M 1.6, was recorded at 1518 on 18 February and was located SE of the crater at a depth of 2 km. Seismicity associated with fluid movement in the conduit decreased in both number and magnitude. These events were mainly associated with ash-and-gas emissions that rose as high as 1 km above the summit and drifted NW. Several thermal anomalies on the crater floor were identified in satellite data; the highest value recorded since 2007 (when this type of monitoring began) was recorded on 15 February. The Alert Level remained at Yellow, Level III (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.

Popocatepetl, Mexico

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

CENAPRED reported that eruptive activity continued at Popocatépetl during 14-20 February. Long-period events totaling 9-330 per day were accompanied by steam-and-gas plumes that occasionally contained minor amounts of ash. The seismic network recorded from 9 to almost 24 hours of daily tremor, often characterized as high frequency and low amplitude. The Washington VAAC reported that daily ash plumes visible in webcam and/or satellite images rose to km (19,000-20,000 ft) a.s.l. and drifted N, NE, SSE, and S. Based on information from El Centro Nacional de Comunicación y Operación de Protección Civil (CENACOM), CENAPRED noted that at 0830 on 14 February minor amounts of ashfall was reported in the municipalities of Nativitas (40 km NE), Santa Isabel (45 km ESE), Tetlatlahuaca (42 km NE), Tlaxcala (51 km NE), Santa Ana Chiautempan, and Zacatelco (45 km NE). Additionally, the Hermanos Serdán International Airport, located 30 km NE in the municipality of Huejotzingo, was closed during 0800-1300 so that ashfall could be cleared from the runway. Later that afternoon ashfall was reported in Puebla (43 km E). Minor ashfall was reported in the municipality of Hueyapan (17 km SSW) at 2025 on 19 February. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay 12 km away from the crater.

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 the eruption at Sabancaya continued at moderate levels during 12-18 February with a daily average of 35 explosions. Gas-and-ash plumes rose as high as 2.6 km above the summit and drifted less than 10 km E, SE, and W. 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). 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 14-20 February. Daily gray-and-white ash plumes rose 400-1,000 m above the summit and drifted in multiple directions. The plumes were often dense. 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 the eruption at Sheveluch continued during 8-15 February with a daily thermal anomaly identified in satellite images. 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.

Shishaldin, Fox Islands (USA)

54.756°N, 163.97°W | Summit elev. 2857 m

AVO reported that low-level unrest at Shishaldin continued during 13-20 February. Occasional small volcanic earthquakes were recorded daily by the seismic network. Robust steaming was observed in satellite and webcam images and reported by local pilots on 13 February, and minor steaming was visible in satellite and webcam images during 14-15 February. AVO noted that steam emissions were not uncommon at Shishaldin. At 1126 on 17 February AVO lowered the Volcano Alert Level to Advisory (the second lowest level on a four-level scale) and the Aviation Color Code to Yellow (the second lowest color on a four-color scale) noting that there were no signs of eruptive activity.

Geological summary: The symmetrical glacier-covered Shishaldin in the Aleutian Islands is the westernmost of three large stratovolcanoes in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning “mountain which points the way when I am lost.” Constructed atop an older glacially dissected edifice, it is largely basaltic in composition. Remnants of an older edifice are exposed on the W and NE sides at 1,500-1,800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is covered by massive aa lava flows. Frequent explosive activity, primarily consisting of Strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century. A steam plume often rises from the summit crater.

Suwanosejima, Ryukyu Islands (Japan)

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

JMA reported that the eruption at Suwanosejima’s Ontake Crater continued during 12-19 February. Crater incandescence was observed in webcam images nightly. Eruptive events at 0810 and 1414 on 13 February generated ash plumes that rose 1.1-1.3 km above the crater rim and drifted N. An explosion at 1908 on 15 February generated an ash plume that rose 400 m and drifted E. Explosions were also detected at 2125 on 15 February and at 0616 on 19 February, though details of emissions were unknown. 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.

Taal, Luzon (Philippines)

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

In a special report issued for Taal on 19 February, PHIVOLCS noted that sulfur dioxide emissions were as high as 14,211 tonnes per day (t/d) and that a sulfur odor was reported in the neighborhoods of Bilibinwang and Banyaga, in the Municipality of Agoncillo. Sulfur dioxide emissions have been continuously released since 2021 and averaged 10,000 t/d during January-February 2024. Seismicity has been low in 2024 with only 17 volcanic earthquakes, mainly associated with gas emissions. 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).

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.

Ubinas, Peru

16.345°S, 70.8972°W | Summit elev. 5608 m

Instituto Geofísico del Perú (IGP) reported that a lahar descended the Volcánmayo drainage on the SE flank at Ubinas at 1645 on 19 February. The report noted that the lahars traveled towards the Ubinas River. The public was warned to stay away from the drainage and to avoid driving on the Querapi-Ubinas-Huarina highway.

Geological summary: The truncated appearance of Ubinas, Perú’s most active volcano, is a result of a 1.4-km-wide crater at the summit. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45°. The steep-walled, 150-m-deep summit crater contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3,700 years ago extend 10 km from the volcano. Widespread Plinian pumice-fall deposits include one from about 1,000 years ago. Holocene lava flows are visible on the flanks, but activity documented since the 16th century has consisted of intermittent minor-to-moderate explosive eruptions.

Villarrica, Central Chile

39.42°S, 71.93°W | Summit elev. 2847 m

SERNAGEOMIN reported that the eruption at Villarrica continued during 12-20 February. At 1937 on 12 February a long-period (LP) earthquake associated with fluid movement was accompanied by a gas emission with minor ash content that rose 420 m above the vent and drifted SW. LP earthquakes at 2206 on 13 February and 0153 on 14 February were accompanied by Strombolian explosions that ejected material 40-60 m high. The ejected material fell back into the crater. LP events were recorded at 0740 on 15 February and 0228 on 17 February, though no emissions were visible on the 15th and weather conditions prevented visual observations on the 17th. The Volcanic Alert level remained at Yellow (the second lowest level on a four-level scale) and the public was warned to stay 1 km away from the active crater.

Geological summary: The glacier-covered Villarrica stratovolcano, in the northern Lakes District of central Chile, is ~15 km south of the city of Pucon. A 2-km-wide caldera that formed about 3,500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesite cone at the NW margin of a 6-km-wide Pleistocene caldera. More than 30 scoria cones and fissure vents are present on the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Eruptions documented since 1558 CE have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks.

References

¹ Smithsonian Institution / US Geological Survey – Weekly Volcanic Activity Report – February 14 – 2024 – Managing Editor: Sally Sennert.

Featured image credit: TW

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