The Weekly Volcanic Activity Report: November 2 - 8, 2022

New activity/unrest was reported for 4 volcanoes from November 2 to 8, 2022. During the same period, ongoing activity was reported for 20 volcanoes.

New activity/unrest: Bezymianny, Central Kamchatka (Russia) | Kerinci, Central Sumatra | Manam, Northeast of New Guinea | Villarrica, Central Chile.

New activity/unrest

Bezymianny, Central Kamchatka (Russia)

55.972°N, 160.595°E | Summit elev. 2882 m

KVERT reported that during 27 October-1 November a thermal anomaly over Bezymianny was identified in satellite images. Strong fumarolic activity was visible, the lava dome continued to grow and was sometimes incandescent at night, and occasional collapses from the dome produced avalanches of hot material. The activity had significantly decreased by 2 November. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale).

Geological summary: The modern Bezymianny, much smaller than its massive neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed about 4,700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7,000 years ago. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Kerinci, Central Sumatra

1.697°S, 101.264°E | Summit elev. 3800 m

PVMBG reported that diffuse white-and-brown plumes from Kerinci rose as high as 400 m above the summit and drifted NE and NW on most days during 2-7 November. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale). The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 3-km exclusion zone.

Geological summary: Gunung Kerinci in central Sumatra forms Indonesia’s highest volcano and is one of the most active in Sumatra. It is capped by an unvegetated young summit cone that was constructed NE of an older crater remnant. There is a deep 600-m-wide summit crater often partially filled by a small crater lake that lies on the NE crater floor, opposite the SW-rim summit. The massive 13 x 25 km wide volcano towers 2400-3300 m above surrounding plains and is elongated in a N-S direction. Frequently active, Kerinci has been the source of numerous moderate explosive eruptions since its first recorded eruption in 1838.

Manam, Northeast of New Guinea

4.08°S, 145.037°E | Summit elev. 1807 m

The Darwin VAAC reported that on 7 November an ash plume from Manam rose to 2.1 km (7,000 ft) and drifted NE based on satellite images and weather models. The plume had dissipated within four hours.

Geological summary: The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country’s most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island’s shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Villarrica, Central Chile

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

SERNAGEOMIN and Observatorio Argentino de Vigilancia Volcánica (OAVV) reported that activity at Villarrica increased during 1 October-7 November. Seismic signals indicated above-baseline activity, including intensifying continuous tremor and an increase in the number of long-period earthquakes. The largest earthquake was a M 2.3 event located 5.3 km ESE of the crater at a depth of 4.8 km. Acoustic data indicated that explosions became larger. Sulfur dioxide emissions recorded on two stations, 10 km ENE and 6 km ESE, averaged around 541 tons per day, with a maximum value of 1,273 tons per day on 13 October; the values were within normal ranges, though they were preceded by two months with high values. Sulfur dioxide emissions were identified in satellite images on 1 November.

The lava lake occupied an area of about 36 square meters on the crater floor based on a 14 October satellite image. During October webcam images showed eruption plumes rising as high as 460 m above the crater rim. Plumes deposited tephra on the E, S, and SW flanks within 500 m of the crater on 2, 18, 23, and 31 October. Nighttime crater incandescence seen in webcam images intensified during 1 October-7 November, and strombolian explosions ejected incandescent tephra onto the NW and SW flanks on 18 and 31 October and during 1, 2, and 6-7 November. Thermal anomalies were identified in satellite images on 2, 10, 15, 22, 27, and 31 October, and 1, 4, and 6 November. POVI reported that the width of lava fountains rising above the crater rim on 2 November suggested that the vent on the crater floor was about 6 m in diameter. Analysis of satellite images and reports from observers indicated that more material was being ejected onto the upper flanks in November, with clasts up to 20 cm in diameter and deposits trending NW. On 8 November SERNAGEOMIN raised the Alert Level to Yellow (the second lowest level on a four-color scale) and warned that material could be ejected within 500 m of the crater. ONEMI declared an Alert Level Yellow (the middle level on a three-color scale) for the municipalities of Villarrica, Pucón (16 km N), Curarrehue, and the commune of Panguipulli.

Geological summary: Glacier-clad Villarrica, one of Chile’s most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km-wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot 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. Historical eruptions, documented since 1558, 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.

Ongoing activity

Aira, Kyushu (Japan)

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

JMA reported ongoing eruptive activity at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) and nighttime crater incandescence during 31 October-7 November. Six eruptive events and two explosions produced volcanic plumes that rose as high as 1.3 km above the crater rim and ejected large blocks as far as 900 m from the vent. Sulfur dioxide emissions were slightly high on 1 November at 1,900 tons per day. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

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.

Alaid, Kuril Islands (Russia)

50.861°N, 155.565°E | Summit elev. 2285 m

KVERT reported that the eruption at Alaid was ongoing during 27 October-3 November. A daily thermal anomaly was identified in satellite images. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Geological summary: The highest and northernmost volcano of the Kuril Islands, 2285-m-high Alaid is a symmetrical stratovolcano when viewed from the north, but has a 1.5-km-wide summit crater that is breached widely to the south. Alaid is the northernmost of a chain of volcanoes constructed west of the main Kuril archipelago. Numerous pyroclastic cones dot the lower flanks of this basaltic to basaltic-andesite volcano, particularly on the NW and SE sides, including an offshore cone formed during the 1933-34 eruption. Strong explosive eruptions have occurred from the summit crater beginning in the 18th century. Reports of eruptions in 1770, 1789, 1821, 1829, 1843, 1848, and 1858 were considered incorrect by Gorshkov (1970). Explosive eruptions in 1790 and 1981 were among the largest in the Kuril Islands during historical time.

Askja, Iceland

65.033°N, 16.783°W | Summit elev. 1080 m

On 9 November Icelandic Meteorological Office (IMO) lowered the Aviation Color Code for Askja to Green (the lowest level on a four-color scale) noting that although deformation data indicted continuing magma accumulation at depth, with a total uplift of 40 cm since August 2021, it was not accompanied by elevated seismicity.

Geological summary: Askja is a large basaltic central volcano that forms the Dyngjufjöll massif. It is truncated by three overlapping calderas, the largest of which is 8 km wide and may have been produced primarily from subglacial ring-fracture eruptions rather than by subsidence. A major rhyolitic explosive eruption from Dyngjufjöll about 10,000 years ago was in part associated with the formation of Askja caldera. Many postglacial eruptions also occurred along the ring-fracture. A major explosive eruption on the SE caldera margin in 1875 was one of Iceland’s largest during historical time. It resulted in the formation of a smaller 4.5-km-wide caldera, now filled by Öskjuvatn lake, that truncates the rim of the larger central caldera. The 100-km-long Askja fissure swarm, which includes the Sveinagja graben, is also related to the Askja volcanic system, as are several small shield volcanoes such as Kollatadyngja. Twentieth-century eruptions have produced lava flows from vents located mostly near Öskjuvatn lake.

Bagana, Bougainville (Papua New Guinea)

6.137°S, 155.196°E | Summit elev. 1855 m

The Darwin VAAC reported that on 2 November ash plumes from Bagana rose to 2.1 km (7,000 ft) a.s.l. and drifted NE based on satellite data. A thermal anomaly was present at the summit.

Geological summary: Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia’s youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.

Dukono, Halmahera

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

PVMBG reported that daily white-and-gray ash plumes from Dukono rose as high as 400 m above the summit and drifted NE, 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: 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

KVERT reported that moderate activity at Ebeko was ongoing. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions on 28 and 31 October and 1 November generated ash plumes that rose to 3.6 km (11,800 ft) a.s.l. and drifted in eastern directions. Ash plumes drifted 110 km SE on 1 November. A thermal anomaly was identified in satellite images during 1-3 November. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

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

Fuego, South-Central Guatemala

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

INSIVUMEH reported that 4-10 explosions per hour were recorded at Fuego during 1-8 November, generating daily ash plumes that rose as high as 1.1 km above the crater rim. The ash plumes drifted as far as 15 km NW, W, SW, and SSW, causing almost daily ashfall in areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Los Yucales (12 km SW), Sangre de Cristo (8 km WSW), El Porvenir (8 km ENE), San Pedro Yepocapa (8 km NW), La Rochela, San Andrés Osuna, Finca la Asunción, and Ceilán. Daily shock waves rattled structures in communities around the volcano. Daily block avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Honda, Las Lajas (SE), and El Jute (ESE) drainages, often reaching vegetated areas. Explosions ejected incandescent material as high as 200 m above the summit on some of the days.

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

Great Sitkin, Andreanof Islands (USA)

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

AVO reported that slow lava effusion continued at Great Sitkin during 2-8 November and seismicity was low. Satellite images were often cloudy, though elevated surface temperatures were identified almost daily. The flow field continued to grow, with lobes of lava extending more than 600 m E and around 430 m S. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The Great Sitkin volcano forms much of the northern side of Great Sitkin Island. A younger parasitic 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 ancestral volcano and produced a submarine debris avalanche. Deposits from this and an 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. Historical eruptions have been recorded since the late-19th century.

Grimsvotn, Iceland

64.416°N, 17.316°W | Summit elev. 1719 m

On 9 November Icelandic Meteorological Office (IMO) lowered the Aviation Color Code for Grímsvötn to Green (the lowest level on a four-color scale) noting no short-term increases in activity, though long-term trends remained above background levels. Seismicity continued to be characterized as unusual, with an increasing number of earthquakes that were also intensifying over the past months. The levels of deformation had already exceeded the level measured before the last eruption in 2011.

Geological summary: Grímsvötn, Iceland’s most frequently active volcano in recent history, lies largely beneath the vast Vatnajökull icecap. The caldera lake is covered by a 200-m-thick ice shelf, and only the southern rim of the 6 x 8 km caldera is exposed. The geothermal area in the caldera causes frequent jökulhlaups (glacier outburst floods) when melting raises the water level high enough to lift its ice dam. Long NE-SW-trending fissure systems extend from the central volcano. The most prominent of these is the noted Laki (Skaftar) fissure, which extends to the SW and produced the world’s largest known historical lava flow in 1783. The 15 km3 basaltic Laki lavas were erupted over a 7-month period from a 27-km-long fissure system. Extensive crop damage and livestock losses caused a severe famine that resulted in the loss of one-fifth of the population of Iceland.

Kilauea, Hawaiian Islands (USA)

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

HVO reported that lava continued to effuse from a vent in the lower W wall of Kilauea’s Halema`uma`u Crater during 2-8 November entering the lava lake and flowing onto the crater floor. The active part of the lake remained at a steady level all week. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Geological summary: Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.

Mauna Loa, Hawaiian Islands (USA)

19.475°N, 155.608°W | Summit elev. 4170 m

HVO reported continuing unrest at Mauna Loa during 1-8 November. The seismic network detected 13-50 daily small-magnitude (below M 3) earthquakes 2-5 km beneath Mokua’weoweo caldera and 6-8 km beneath the upper NW flank of Mauna Loa. Data from Global Positioning System (GPS) instruments at the summit and flanks showed continuing inflation, though data from tiltmeters at the summit did not show significant surface deformation over the past week. 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 level on a four-color scale).

Geological summary: Massive Mauna Loa shield volcano rises almost 9 km above the sea floor to form the world’s largest active volcano. Flank eruptions are predominately from the lengthy NE and SW rift zones, and the summit is cut by the Mokuaweoweo caldera, which sits within an older and larger 6 x 8 km caldera. Two of the youngest large debris avalanches documented in Hawaii traveled nearly 100 km from Mauna Loa; the second of the Alika avalanches was emplaced about 105,000 years ago (Moore et al. 1989). Almost 90% of the surface of the basaltic shield volcano is covered by lavas less than 4000 years old (Lockwood and Lipman, 1987). During a 750-year eruptive period beginning about 1500 years ago, a series of voluminous overflows from a summit lava lake covered about one fourth of the volcano’s surface. The ensuing 750-year period, from shortly after the formation of Mokuaweoweo caldera until the present, saw an additional quarter of the volcano covered with lava flows predominately from summit and NW rift zone vents.

Merapi, Central Java

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

BPPTKG reported that the eruption at Merapi continued during 28 October-3 November and seismicity remained at high levels. The SW lava dome produced lava avalanches that traveled as far as 1.2 km down the W flank (upstream in the Kali Sat drainage). No significant morphological changes to the central and SW lava domes were evident in drone photographs. 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.

Pavlof, Alaska Peninsula, Alaska

55.417°N, 161.894°W | Summit elev. 2493 m

AVO reported that a minor eruption at a vent on Pavlof’s upper E flank was ongoing during 2-8 November and nearly continuous seismic tremor was recorded. Multiple explosions were detected almost daily in seismic and infrasound data. Trace ash deposits on the NW flank were identified in satellite images during 1-2 November, and minor steaming was visible on 3 November. Minor steam-and-ash emissions were visible in webcam images and observed by pilots during 3-4 November, and ash deposits on the flanks were visible. Elevated surface temperatures were identified in satellite images during 4-8 November. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The most active volcano of the Aleutian arc, Pavlof is a 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing Strombolian to Vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest historical eruption took place in 1911, at the end of a 5-year-long eruptive episode, when a fissure opened on the N flank, ejecting large blocks and issuing lava flows.

Sabancaya, Peru

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

Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 31 October-6 November with a daily average of 30 explosions. Gas-and-ash plumes rose as high as 3 km above the summit and drifted NE, E, and SE. As many as five thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. Minor inflation continued to be detected near Hualca Hualca (4 km N). The Alert Level remained at Orange (the second highest 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.

Sangay, Ecuador

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

IG reported a high level of activity at Sangay during 1-8 November. Almost daily thermal anomalies were identified in satellite images, though weather clouds often prevented views. Incandescence at the summit was periodically visible at night. Daily ash-and-gas plumes were identified in either or both IG webcam photos and satellite images according to the Washington VAAC. Plumes generally rose as high as 2.1 km above the volcano and drifted NW, W, and SW. Ash emissions were first observed at 0520 on 4 November and then the amplitude of tremor signals increased at 0650. A pyroclastic flow descended the Volcán River drainage on the SE flank at 0700. The emissions intensified at 0840 and a plume rose 8.3 km above the crater rim and drifted NW, W, and SW. Minor-to-moderate amounts of ash fell in several cities including Riobamba (50 km NW), Guamote (42 km WNW), Colta (55 km NW), Alausí (60 km SW), Pallatanga (70 km W), Chambo (40 km NW), and Chunchi (73 km SW) during 4-5 November.

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 the open 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 eroded by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of an eruption was in 1628. Almost 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.

Santa Maria, Southwestern Guatemala

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

On 6 November INSIVUMEH reported that activity at Santa María’s Santiaguito lava-dome complex transitioned from more extrusive to more explosive. The rate of lava effusion and advancement of the lava flows in the San Isidro and El Tambor drainages on the W and SW flanks had notably decreased. Explosivity had become more intense and audible in the recent weeks and particularly in the previous few days, according to seismic and infrasound data, webcam images, and reports from surrounding residents. Gas emissions had increased, and sulfur dioxide emissions were identified in satellite images during recent days. Gas, ash, and steam plumes rose as high as 500 m above the dome complex. Block avalanches from the dome, along with the ends and sides of the flows, descended the S, SW, and W flanks. Some block collapses generated ash clouds that rose to several hundred meters high. Lahars descended the Cabello de Ángel drainage (a tributary of Nimá I on the SE flank) on 3 November, carrying tree trunks, branches, and blocks up to 1 m in diameter. Minor ashfall was reported in Finca San José and La Quina on 5 November.

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

Semeru, Eastern Java

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

PVMBG reported that the eruption at Semeru continued during 2-8 November. An eruptive event at 0507 on 3 November produced a white-and-gray ash plume that rose 300 m above the summit. The Alert Level remained at 3 (on a scale of 1-4). The public was warned to stay at least 5 km away from the summit, and 500 m from Kobokan drainages within 17 km of the summit, along with other drainages originating on Semeru, 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.

Semisopochnoi, Aleutian Islands (USA)

51.93°N, 179.58°E | Summit elev. 1221 m

On 7 November AVO stated that small explosions at the N crater of Mount Cerberus at Semisopochnoi had been detected in geophysical data during the previous week and volcanic tremor simultaneously resumed. Though ash emissions were not visually observed, the type of unrest was similar to previous periods associated with ash emissions below 3 km (10,000 ft) a.s.l.; the Aviation Color Code was raised to Orange (the second highest level on a four-color scale) and the Volcano Alert Level was raised to Watch (the second highest level on a four-level scale). Seismicity was low during 7-8 November, and clouds prevented webcam and satellite images.

Geological summary: Semisopochnoi, the largest subaerial volcano of the western Aleutians, is 20 km wide at sea level and contains an 8-km-wide caldera. It formed as a result of collapse of a low-angle, dominantly basaltic volcano following the eruption of a large volume of dacitic pumice. The high point of the island is Anvil Peak, a double-peaked late-Pleistocene cone that forms much of the island’s northern part. The three-peaked Mount Cerberus was constructed within the caldera during the Holocene. Each of the peaks contains a summit crater; lava flows on the N flank of Cerberus appear younger than those on the south side. Other post-caldera volcanoes include the symmetrical Sugarloaf Peak SSE of the caldera and Lakeshore Cone, a small cinder cone at the edge of Fenner Lake in the NE part of the caldera. Most documented eruptions have originated from Cerberus, although Coats (1950) considered that both Sugarloaf and Lakeshore Cone could have been recently active.

Sheveluch, Central Kamchatka (Russia)

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

KVERT reported that the ongoing eruption at Sheveluch during 27 October-3 November was generally characterized by explosions, hot avalanches, and lava-dome extrusion. A daily thermal anomaly was identified in satellite images. Collapses generated hot avalanches and ash plumes that drifted 200 km SE on 31 October and 1 November. The Kamchatka Volcano Station reported that activity notably increased on 5 November. Debris avalanches and small pyroclastic flows were visible throughout the day and incandescent avalanches were seen traveling SE and SW at night. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

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

Suwanosejima, Ryukyu Islands (Japan)

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

JMA reported that the eruption at Suwanosejima’s Ontake Crater continued during 31 October-7 November and crater incandescence was visible nightly. An explosion at 0137 on 4 November produced an eruption plume that rose 2.4 km above the crater rim and ejected large blocks 200 m from the vent. Ashfall was reported in Toshima village (3.5 km SSW). The Alert Level remained at 2 and the public was warned to stay 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 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. 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 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 open 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.

References:

Smithsonian / US Geological Survey Weekly Volcanic Activity Report – November 2 – 8, 2022 – Managing Editor: Sally Kuhn Sennert

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