The Weekly Volcanic Activity Report: March 3 - 9, 2021

The Weekly Volcanic Activity Report: March 3 - 9, 2021

New activity/unrest was reported for 8 volcanoes from March 3 to 9, 2021. During the same period, ongoing activity was reported for 12 volcanos.

New activity/unrest: Etna, Sicily (Italy) | Klyuchevskoy, Central Kamchatka (Russia) | Krysuvik, Iceland | Pacaya, Guatemala | Pinatubo, Luzon (Philippines) | Sinabung, Indonesia | Taal, Luzon (Philippines) | Veniaminof, United States.

Ongoing activity: Aira, Kyushu (Japan) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Kikai, Japan | Kilauea, Hawaiian Islands (USA) | Lewotolok, Lembata Island (Indonesia) | Merapi, Central Java (Indonesia) | Raung, Eastern Java (Indonesia) | Sangay, Ecuador | Sheveluch, Central Kamchatka (Russia) | Soufriere St. Vincent, St. Vincent | Suwanosejima, Ryukyu Islands (Japan).

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 23:00 UTC every Wednesday, these reports are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports about recent activity are published in issues of the Bulletin of the Global Volcanism Network.

New activity/unrest

Etna, Sicily (Italy)

37.748°N, 14.999°E, Summit elev. 3320 m

INGV reported continuing episodes of lava fountaining at Etna’s Southeast Crater (SEC) on 2, 4, and 7 March. Weak Strombolian activity began at SEC at 1145 on 2 March, then intensified at 1234 and produced an ash plume. Lava fountaining began at 1324. Ash plumes rose to 9 km above the summit and drifted S, causing lapilli to fall in Nicolosi (16 km S), Aci San Antonio (18 km SE), Pedara (15 km SSE), and Catania (29 km SSE). Lava fountaining ceased at 1550, ending the eighth episode.

The ninth episode began at the SEC as weak Strombolian at 0120 on 4 March. Ash emissions were visible at 0200 but dispersed quickly. Strombolian activity at Voragine (VOR) was also visible with ejected material rising above the crater rim. Lava fountaining began at SEC at 0320, but by 0515 the activity had decreased. Lava flows that advanced towards the Valle de Bove were fed by spattering and a new vent that opened at the E base of the SEC. Strombolian activity at VOR changed to 300-m-tall lava fountaining at 0850. Ash plumes rose 11 km above the summit and caused lapilli to fall in Fiumefreddo (19 km ENE), Linguaglossa (17 km NE), and the area of Reggio Calabria.

The tenth episode began with Strombolian explosions at SEC and minor lava effusion at the new vent at the E base of SEC during the first hour on 7 March. Strombolian activity intensified at 0430; an eruption plume rose 5 km above the summit and drifted E. Lava overflowed the SEC onto the E flank and expanded into the Valle de Bove, reaching an elevation of 2,800 m by 0450. Strombolian activity again intensified beginning at 0520 and the lava flow advanced to 2,700 m elevation. Lava fountaining started at 0720 and ended at 0810. An eruption plume rose 10 km and drifted E. Ash and lapilli fell in Milo (11 km ESE), Fornazzo (10 km ESE), Trepunti (17 km ESE), Giarre (17 km ESE), Macchia di Giarre (16 km ESE), Mascali (18 km E), Riposto (19 km ESE), and Torre Archirafi (20 km ESE). Strombolian activity resumed at 1050 and was over by 1500.

Strombolian activity at SEC returned at 1914 on 9 March. Lava overflowed the crater at 2013 and advanced towards the Valle de Bove. Strombolian activity increased at 2100 and ash emissions drifted NE. The lava flow reached 2,900 m elevation.

Geological summary: Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical 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 horseshoe-shaped 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.

Klyuchevskoy, Central Kamchatka (Russia)

56.056°N, 160.642°E, Summit elev. 4754 m

KVERT reported that the eruption from vents on Klyuchevskoy’s lower NW flank continued during 26 February-5 March. A large, bright thermal anomaly over the vents was identified daily in satellite images. IVS FEB RAS volcanologists visited the field site on 2 March during good weather conditions. They estimated that the cinder cone was 54 m high and 101 m wide at the base. Lava effused from the cone and traveled downslope, melting ice and snow that formed muddy streams. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Krysuvik, Iceland

63.883°N, 22.083°W, Summit elev. 360 m

IMO reported that seismicity in the area between the Krýsuvík and Reykjanes-Svartsengi volcanic systems remained elevated during 4-10 March. GPS and InSAR data indicated that the intrusion was ongoing, with magma moving slowly SW along a fault between Keilir and Fagradalsfjall at depths of 2-6 km. Seismicity fluctuated during 6-7 March but continued to be elevated; the largest event was a M 5.1 on 7 March. The geophysical and satellite data on 8 March suggested that magma movement had decelerated over the past week, and was possibly as shallow as 1 km. A burst of seismicity was recorded around 0520 on 9 March, concentrated at the S end of the intrusion in an area that was most likely source of the magma. On 10 March IMO stated that more than 34,000 earthquakes had been detected during the past two weeks, a total larger than all of 2020 which was characterized as an unusually high year for seismicity. The Aviation Color Code for Krýsuvík remained at Orange.

Geological summary: The Krysuvík volcanic system (also spelled Krisuvik) consists of a group of NE-SW-trending basaltic crater rows and small shield volcanoes cutting the central Reykjanes Peninsula west of Kleifarvatn lake. Several eruptions have taken place since the settlement of Iceland, including the eruption of a large lava flow from the Ogmundargigar crater row around the 12th century. The latest eruption took place during the 14th century.

Pacaya, Guatemala

14.382°N, 90.601°W, Summit elev. 2569 m

INSIVUMEH and CONRED reported that during 2-6 March strong Strombolian explosions at Pacaya’s Mackenney Crater produced ash plumes that rose as high as 1 km above the summit and drifted W, SW, and S. Tephra fell in areas downwind including El Patrocinio (5 km W), El Rodeo (4 km WSW), San Francisco de Sales (5 km N), El Cedro (9 km NNW), Calderas (3 km N), and Las Jazmines (5 km W), and in the municipalities of Palín (10 km WNW) and Escuintla (22 km SW). Periods of lava fountaining were visible, and incandescent material was ejected 300-1,000 m high. Three lava flows were active and all had several branches; one traveled SSW, one traveled S, and one on the SE flank was 800-1,200 m long. During 6-8 March strong explosions ejected material as high as 500 m and produced dense ash plumes that rose up to 1 km. Lava flows continued to be active, sometimes producing block avalanches from the ends. On 8 March the S-flank flow was about 850 m long and continued to generated block avalanches. Strong explosions during 8-9 March ejected ballistics 300-500 m away from the crater. Dense ash plumes rose up to 1.5 km and drifted 30 km SW and S. The lava flow on the S flank was 900 m long and shed blocks from the end.

Geological summary: Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.

Pinatubo, Luzon (Philippines)

15.13°N, 120.35°E, Summit elev. 1486 m

PHIVOLCS raised the Alert Level for Pinatubo to 1 (on a scale of 0-5) on 4 March noting elevated seismicity with a total of 1,722 earthquakes recorded in two swarms since 20 January. The first swarm was recorded during 20-26 January and was comprised of local M 1-2.5 events that occurred along the Sacobia Lineament fault at depths of 15-28 km. A more persistent swarm followed; it was comprised of local M 0.5-2.8 events at depths of 10-35 km along another fault system, with a few shallower earthquakes occurring at both ends of the swarm. Carbon dioxide flux at Pinatubo Crater lake was 378 tonnes per day in February, within background ranges that topped 1,000 tonnes per day during the last decade. Minor temperature increases were recorded at fumarolic vents.

Geological summary: Prior to 1991 Pinatubo volcano was a relatively unknown, heavily forested lava dome complex located 100 km NW of Manila with no records of historical eruptions. The 1991 eruption, one of the world's largest of the 20th century, ejected massive amounts of tephra and produced voluminous pyroclastic flows, forming a small, 2.5-km-wide summit caldera whose floor is now covered by a lake. Caldera formation lowered the height of the summit by more than 300 m. Although the eruption caused hundreds of fatalities and major damage with severe social and economic impact, successful monitoring efforts greatly reduced the number of fatalities. Widespread lahars that redistributed products of the 1991 eruption have continued to cause severe disruption. Previous major eruptive periods, interrupted by lengthy quiescent periods, have produced pyroclastic flows and lahars that were even more extensive than in 1991.

Sinabung, Indonesia

3.17°N, 98.392°E, Summit elev. 2460 m

PVMBG reported that the eruption at Sinabung continued during 3-9 March. According to the Darwin VAAC an ash plume was identified in satellite images rising to 3 km (10,000 ft) a.s.l. (or 600 m above the summit) and drifting NW on 5 March. The observatory noted that avalanches of material traveled 500 m down the SE flank during 6-7 March, and an ash plume rose 1 km and drifted NW at 1910 on 7 March. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Geological summary: Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. The youngest deposit is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at 740-880 CE. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.

Taal, Luzon (Philippines)

14.002°N, 120.993°E, Summit elev. 311 m

PHIVOLCS raised the Alert Level for Taal to 2 (on a scale of 0-5) on 9 March based on increased activity recorded since 13 February. During 8-9 March the seismic network recorded a total of 28 volcanic tremor events, four low-frequency volcanic earthquakes, and one hybrid event at depths of less than 1.5 km. These events added to the totals of 866 volcanic tremor events and 141 low-frequency volcanic earthquakes recorded during 13 February-9 March. Overall, seismicity over the past month indicated increased magmatic and hydrothermal activity at shallow depths beneath Taal Volcano Island (TVI).

Over the past month minor deformation centered at a source beneath the SE part of TVI was evident in monitoring data, including integrated real-time ground tilt and continuous GPS, daily Electronic Distance Measurement (EDM) monitoring, and InSAR. The data also showed slow and steady inflation across the Taal region after the 2020 eruption. Geochemical data collected from Taal’s Main Crater lake indicated a continuous acidification of the water from pH 2.79 to 1.59 between January 2020 and mid-February 2021. Microgravity data was consistent with magma migration. PHIVOLCS strongly recommended no entry onto the island, and access to the Main Crater and Daang Kastila fissure (along the walking trail) was strictly prohibited.

Geological summary: Taal is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. Though not topographically prominent, its prehistorical eruptions have greatly changed the landscape of SW Luzon. 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, and several eruptive centers lie submerged beneath the lake. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all historical eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones that have grown about 25% in area during historical time. Powerful pyroclastic flows and surges from historical eruptions have caused many fatalities.

Veniaminof, United States

56.17°N, 159.38°W, Summit elev. 2507 m

AVO reported that elevated sulfur dioxide gas emissions at Veniaminof were first detected on 1 March and elevated surface temperatures were identified in satellite images sometime during 2-3 March. At 0513 on 4 March infrasound sensors recorded a small explosion, prompting AVO to raise the Volcano Alert Level to Watch and the Aviation Color Code to Orange. A low-level ash plume, to less than 3 km (10,000 ft) a.s.l., was visible in satellite and webcam images drifting SSE and minor ash deposits around the volcano were visible. Small emissions continued at least through 1048 that day. Sulfur dioxide emissions were visible in a webcam image on 5 March. Numerous small explosions were recorded during 6-7 March; some of them were heard and felt by residents in Perryville (35 km SE). Elevated surface temperatures were identified in satellite images, suggesting lava near or at the surface. During times of clear weather low-level gas-and-ash plumes were visible in satellite and webcam data and observed by pilots. The plumes mainly stayed below 3 km (10,000 ft) a.s.l., but at times went as high as 4.6 km (15,000 ft) a.s.l., and drifted 150 km NE.

On 7 March satellite images revealed that the emissions originated from a small cone in the summit caldera. Additionally, lava was likely effusing under the intra-caldera glacier in an area on the flank about 1 km E of the cone’s summit. This area produced incandescence and strongly elevated surface temperatures, as well as a small steam plume and meltwater. During 8-9 March satellite images showed a small, steam-rich plume drifting about 10 km NE at 4.6 km (15,000 ft) a.s.l.

Geological summary: Veniaminof, on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 years ago. The caldera rim is up to 520 m high on the north, is deeply notched on the west by Cone Glacier, and is covered by an ice sheet on the south. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.

Ongoing activity

Aira, Kyushu (Japan)

31.593°N, 130.657°E, Summit elev. 1117 m

JMA reported that during 1-8 March incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. An explosion at 1810 on 1 March ejected bombs 600-900 m away from the crater; an eruption plume was not confirmed. That same day the sulfur dioxide emission rate was high, at 2,900 tons per day. An explosion on 5 March produced an eruption plume that rose 2.7 km above the summit and ejected bombs 800-1,100 m away. The Alert Level remained at 3 (on a 5-level scale).

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 Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.

Dukono, Halmahera (Indonesia)

1.693°N, 127.894°E, Summit elev. 1229 m

Based on satellite and wind model data, the Darwin VAAC reported that during 7-9 March ash plumes from Dukono rose to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted E, SE, and SW. The Alert Level remained at 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, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. 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

Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 26-28 February and 1-2 March that sent ash plumes to 3.6 km (11,800 ft) a.s.l. and drifted in multiple directions. Ashfall was reported in Severo-Kurilsk on 26 February and 2 March. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

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.

Kikai, Japan

30.793°N, 130.305°E, Summit elev. 704 m

In response to an eruption at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, on 2 November 2019 JMA had raised the Alert Level to 2 (on a 5-level scale). Since then, surveillance cameras sometimes recorded minor incandescence reflected in emitted plumes. On 8 March JMA revised the Alert Level guidelines, keeping the level at 2, but reducing the exclusion zone around the crater from 1 km to 500 m.

Geological summary: Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. It was the source of one of the world's largest Holocene eruptions about 6,300 years ago when rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km E of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.

Kilauea, Hawaiian Islands (USA)

19.421°N, 155.287°W, Summit elev. 1222 m

HVO reported that a vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 2-8 March through a submerged inlet. The sulfur dioxide emission rate was 1,000 tons/day during 2-3 March, and 800 tons/day on 7 March. The depth of the western part of the lake fluctuated around 219-220 m. The E half of the lake remained solidified and lower that the W half, with the crusted E half expanding towards the W. Rangefinder measurements and visual observations indicated that the eastern and western portions of the lake were rising at the same rate, suggesting that lava was accumulating under the crusted eastern portion.

In recent weeks a part of the cone, several meters NE of the main vent, occasionally fed short (less than 100 m) lava flows that entered the lake at the crusted margins. During 5-7 March flows from this vent poured lava into the lake at several shifting inlets, though lava also accumulated on the lake margin within 50 m of the vent. By midday on 7 March the flows had built a perched lava pond on the NW lake margin, but it abruptly collapsed just after 1300. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Geological summary: Kilauea, which overlaps the E flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 km2, destroying nearly 200 houses and adding new coastline to the island.

Lewotolok, Lembata Island (Indonesia)

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

PVMBG reported that the eruption at Lewotolok continued during 3-9 March; weather conditions sometimes hindered visual observations. Gray-and-white ash plumes rose 100-1,000 m above the summit and drifted E, SE, SW, and W. Incandescent material was ejected 300-800 m SE from the crater during 3-6 March. Rumbling and occasional thumping sounds were reported. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 4 km away from the summer 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.

Merapi, Central Java (Indonesia)

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

BPPTKG reported that the 2021 lava dome just below Merapi’s SW rim and the new lava dome in the summit crater both continued to grow during 19-25 February. The 2021 lava-dome volume was an estimated 618,700 cubic meters on 25 February, with a growth rate of about 13,600 cubic meters per day. A total of three pyroclastic flows traveled 1.9 km down the SW flank. One of the three, recorded at 1652 on 25 February, was followed by minor ashfall in Kali Tengah Lor, Kali Tengah Kidul, Deles, and Tlukan. The Alert Level remained at 3 (on a scale of 1-4), and the public were warned to stay 5 km away from the summit. 

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.

Raung, Eastern Java (Indonesia)

8.119°S, 114.056°E, Summit elev. 3260 m

PVMBG reported that daily gray ash plumes rose 200-1,200 m above Raung’s summit during 2-9 March. Ash plumes drifted mainly E and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Geological summary: Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The unvegetated summit is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and W, respectively.

Sangay, Ecuador

2.005°S, 78.341°W, Summit elev. 5286 m

IG reported a high level of activity at Sangay during 3-9 March. Seismicity was characterized by daily explosions, long-period earthquakes, and signals indicating emissions. Weather clouds often prevented visual observations of the volcano, but satellite and webcam images recorded daily ash plumes.

Ash plumes were notable during 5-6 March and impacted communities downwind with ashfall. According to the Washington VAAC ash plumes rose 5.8-12.2 km (19,000-40,000 ft) a.s.l. and drifted 170-370 km SW, W, and NW; ash at altitudes of 5.8-8.2 km (19,000-27,000 ft) a.s.l. drifted 185 km E. During 5-6 March ashfall was reported in Alfredo Baquerizo Moreno (132 km W), but fell more significantly in Alausí (61 km WSW), Chunchi (73 km SW), Cumandá (90 km WSW), Guamote (42 km WNW), Pallatanga (70 km W), Milagro (140 km W), San Jacinto de Yaguachi (150 km W), Samborondon (170 km W), Daule (180 km W), and Durán (168 km W). SNGRE reported that the ashfall affected a total of 108,457 people (23,750 families) as well as numerous crops and animals; they distributed volcano-related aid kits to impacted populations.

Ashfall continued to impact multiple communities during 6-7 March. Ash fell in Guayaquil (175 km W), General Antonio Elizalde (97 km WSW), Simón Bolívar, Milagro (140 km W), San Jacinto de Yaguachi (150 km W), El Triunfo (125 km WSW), Daule, Samboróndon (170 km W), Coronel Marceliño Maridueña (120 km WSW), Durán, Naranjito, Alfredo Baquerizo Moreno, Playas (240 km WSW), Guamote (40 km WNW), Alausí (60 km SW), Pallatanga (70 km W), Chunchí (72 km SW), and Colta (55 km NW).

Geological summary: The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador's volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex.

Sheveluch, Central Kamchatka (Russia)

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

KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 26 February-5 March. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. 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 dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. 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.

Soufriere St. Vincent, St. Vincent

13.33°N, 61.18°W, Summit elev. 1220 m

University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that the lava dome in Soufrière St. Vincent’s main crater continued to slowly grow during 2-8 March. The SE part of the dome was in line with the pre-existing fumarolic area on the 1979 dome. Gas plumes continued to damage vegetation in the summit area as well as on the SW flank. The Alert Level remained at Orange (the second highest level on a four-color scale).

Geological summary: Soufrière St. Vincent is the northernmost and youngest volcano on St. Vincent Island. The NE rim of the 1.6-km wide summit crater is cut by a crater formed in 1812. The crater itself lies on the SW margin of a larger 2.2-km-wide caldera, which is breached widely to the SW as a result of slope failure. Frequent explosive eruptions after about 4,300 years ago produced pyroclastic deposits of the Yellow Tephra Formation, which cover much of the island. The first historical eruption took place in 1718; it and the 1812 eruption produced major explosions. Much of the northern end of the island was devastated by a major eruption in 1902 that coincided with the catastrophic Mont Pelée eruption on Martinique. A lava dome was emplaced in the summit crater in 1971 during a strictly effusive eruption, forming an island within a lake that filled the crater. A series of explosive eruptions in 1979 destroyed the 1971 dome and ejected the lake; a new dome was then built.

Suwanosejima, Ryukyu Islands (Japan)

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

JMA reported intermittent eruptive events at Suwanosejima’s Ontake Crater during 26 February-2 March. Bombs were ejected as far as 600 m away from the crater and ashfall was reported in Toshima village (4 km SSW). The number of explosions began increasing on 2 March; the total recorded through 1500 on 7 March was 139, but by 1500 on 8 March there was only one additional explosion. The Tokyo VAAC reported that ash plumes rose 0.9-2.1 km (3,000-7,000 ft) a.s.l. during 3-7 March. An explosion at 0317 on 6 March ejected tephra as high as 500 m above the crater rim and bombs 900 m away. The Alert Level remained at 2 (on a 5-level scale).

Geological summary: The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed 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 the horseshoe-shaped Sakuchi caldera, which extends 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.

Source: GVP

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