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

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

New activity/unrest was reported for 4 volcanoes from November 3 to 9, 2021. During the same period, ongoing activity was reported for 16 volcanoes.

New activity/unrest: Karymsky, Eastern Kamchatka (Russia) | Krakatau, Indonesia | Manam, Papua New Guinea | Turrialba, Costa Rica.

Ongoing activity: Aira, Kyushu (Japan) | Ebeko, Paramushir Island (Russia) | Great Sitkin, Andreanof Islands (USA) | Kadovar, Papua New Guinea | Kilauea, Hawaiian Islands (USA) | La Palma, Spain | Merapi, Central Java (Indonesia) | Nevado del Ruiz, Colombia | Pavlof, United States | Semisopochnoi, Aleutian Islands (USA) | Sheveluch, Central Kamchatka (Russia) | Suwanosejima, Ryukyu Islands (Japan) | Taal, Luzon (Philippines) | Telica, Nicaragua | Villarrica, Chile | Whakaari/White Island, North Island (New Zealand).

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.

New activity/unrest

Karymsky, Eastern Kamchatka (Russia)

54.049°N, 159.443°E, Summit elev. 1513 m

KVERT reported that during 29 October-2 November explosions at Karymsky generated ash plumes that rose as high as 4 km (13,100 ft) a.s.l. and drifted 135 km E and SE. According to the Tokyo VAAC ash plumes rose as high as 7.9 km (26,000 ft) a.s.l. on 3 November and drifted SE and E.

A powerful explosive eruption on 4 November generated notable ash plumes described in a series of VONAs issued by KVERT and volcanic ash advisories (VAAs) issued by the Tokyo and Anchorage VAACs. On 4 November ash plumes rose 3-9.5 km (10,000-31,200 ft) a.s.l. and drifted E. Satellite images acquired at 1750 showed two large ash clouds, one was 400 x 560 km in extent and had drifted 1,090 km E and the second was 80 x 280 km and had drifted 460 km SE. On 5 November ash plumes rose 3-5.5 km (10,000-18,000 ft) a.s.l. and drifted E and NE. Additional explosions at 1540 on 6 November generated ash plumes that rose 7.5-8 km (24,600-26,200 ft) a.s.l. and drifted ENE, prompting KVERT to raise the Aviation Color Code to Red (the highest level on a four-color scale). Observers on Medny and Bering islands reported ashfall. Activity waned, but at 1305 on 7 November more ash plumes rose to 4-4.6 km (13,100-15,000 ft) a.s.l. and drifted 110 km NNE; KVERT lowered the Aviation Color Code to Orange.

Geological summary: Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed during the early Holocene. The caldera cuts the south side of the Pleistocene Dvor volcano and is located outside the north margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7600-7700 radiocarbon years ago; construction of the stratovolcano began about 2000 years later. The latest eruptive period began about 500 years ago, following a 2300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been vulcanian or vulcanian-strombolian with moderate explosive activity and occasional lava flows from the summit crater.

Krakatau, Indonesia

6.102°S, 105.423°E, Summit elev. 155 m

PVMBG reported that during periods of clear weather during 2-9 November white plumes from Anak Krakatau were visible rising as high as 100 m above the summit. White-to-gray plumes were seen in webcam images during 6-7 November rising 150 m and crater incandescence was visible three times. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km-radius hazard zone from the crater.

Geological summary: The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.

Manam, Papua New Guinea

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

The Darwin VAAC reported that on 3 and 8 November ash plumes from Manam rose to 1.8 km (6,000 ft) a.s.l. and drifted NW and W based on satellite data and weather models.

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.

Turrialba, Costa Rica

10.025°N, 83.767°W, Summit elev. 3340 m

OVSICORI-UNA reported that a one-minute-long eruption at Turrialba was recorded at 0646 on 3 November and produced a plume that rose 200 m above the crater rim and drifted W. Another small eruption was recorded on 7 November.

Geological summary: Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive edifice covers an area of 500 km2. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

Ongoing activity

Aira, Kyushu (Japan)

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

JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 1-8 November. An eruption at 2225 on 2 November produced a plume that rose 1.1 km above the crater rim and drifted SW. The sulfur dioxide emission rate was 1,000 tons per day on 4 November. Very small eruptions were detected during 5-8 November. 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.

Ebeko, Paramushir Island (Russia)

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

According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, an explosion on 2 November produced an ash plume that rose as high as 2.6 km (8,500 ft) a.s.l. and drifted SE. 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.

Great Sitkin, Andreanof Islands (USA)

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

AVO reported that lava flows at Great Sitkin were approximately 680 m long on the W flank, 560 m long on the S flank, and 90 m long on the N flank by 30 October based on satellite images. Lava effusion probably continued during 3-9 November, though weather clouds prevented visual confirmation. Elevated surface temperatures were occasionally detected in satellite images during 2-3 and 5-6 November. Seismicity was low overall, though slightly increased during 6-7 November. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

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.

Kadovar, Papua New Guinea

3.608°S, 144.588°E, Summit elev. 365 m

Based on satellite and wind model data, the Darwin VAAC reported that on 3 and 5 November ash plumes from Kadovar rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted W.

Geological summary: The 2-km-wide island of Kadovar is the emergent summit of a Bismarck Sea stratovolcano of Holocene age. It is part of the Schouten Islands, and lies off the coast of New Guinea, about 25 km N of the mouth of the Sepik River. Prior to an eruption that began in 2018, a lava dome formed the high point of the andesitic volcano, filling an arcuate landslide scarp open to the south; submarine debris-avalanche deposits occur in that direction. Thick lava flows with columnar jointing forms low cliffs along the coast. The youthful island lacks fringing or offshore reefs. A period of heightened thermal phenomena took place in 1976. An eruption began in January 2018 that included lava effusion from vents at the summit and at the E coast.

Kilauea, Hawaiian Islands (USA)

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

HVO reported that the summit eruption at Kilauea continued during 2-9 November at a vent in the lower W wall of Halema`uma`u Crater. Lava entered the lake through a short channel in the E part of the W wall cone, feeding the lake which had risen 56 m since 29 September; the channel was covered with a cooled crust by 3 November. Lava began to flow over the E edge of the lava lake, which is perched above the crater floor, by 4 November. The sulfur dioxide emission rate was 1,700-2,900 tonnes per day during 3-5 November and 250 tonnes per day during 7-8 November. Low roiling and bursts of spatter from the small perched pond in the W vent cone were observed; activity at the vent had decreased by 8 November, along with the area of active lava at the surface of the main lava lake, then returned to higher levels by 9 November. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

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.

La Palma, Spain

28.57°N, 17.83°W, Summit elev. 2426 m

The eruption at La Palma continued during 2-9 November, characterized by Strombolian explosions and lava fountaining from multiple vents, advancing and branching lava flows, and daily ash emissions. Eruption details are based on official sources including PEVOLCA (Plan de Emergencias Volcánicas de Canarias) steering committee daily summaries. Volcanic tremor levels decreased around noon on 2 November and again during 4-5 November, and remained at low levels through 9 November. Most earthquakes were located 10-15 km deep (though some were as deep as 38 km); dozens of events were felt by local residents and some were felt across the entire island. At 0824 on 3 November a M 4.8 located 36 km deep was followed three seconds later by a M 5 at 35 km depth; they were perceived by residents as one long event; the M 5 was the largest earthquake of the week. Two other notable earthquakes occurred consecutively; a M 4.6 at a depth of 37 km at 1807 on 7 November was followed eight seconds later by a M 4.5 at 38 km depth. Some of the larger earthquakes were felt across La Palma Island, as well as in some areas of La Gomera and Tenerife islands. In general, decreases were observed in the levels of seismicity, tremor, deformation, and sulfur dioxide emissions, though by 9 November the data continued to fluctuate with no consistent trends.

The vents in the main cone continued to effuse lava, eject tephra, sometimes producing dense billowing ash-and-gas plumes that rose 2.5-3.5 km (8,200-11,500 ft) a.s.l. and drifted WSW, SW, and SSE. Several vents in the main cone were active, though the activity levels varied in intensity throughout the week. Weather conditions and large amounts of emitted ash resulted in air quality alerts issued daily by authorities as they warned residents of some affected areas (Los Llanos de Aridane, Tazacorte, El Paso, Puntagorda, and Tijarafe) to stay indoors; air quality was “extremely unfavorable” on most days then upgraded to “unfavorable” on 9 November. Sulfur dioxide emissions fluctuated at high levels between 9,000 and 31,300 tons per day and showed an overall decrease. On 5 November photos showed sulfur deposits on the E flank on the main cone and in other areas near vents emitting volcanic gases.

Lava continued to flow west through pre-existing lava channels and tubes, over older flows, and occasionally formed new branches. The flows were numbered 1-11. Flow 11 originated at the end of October along the upper central part of the S margin of the flow field, N of Montaña Cogote; by 3 November it was 100 m from the LP-211 road and on 6 November the advancement rate increased. Lava number 2, located between the main flow, number 1, that had reached the ocean on 21 September and flow number 9 which had previously branched off of the main flow to the S, advanced during 8-9 November. The flow reached the sea cliff at Los Guirres Beach and then entered the ocean at 0245 on 9 November. Overall, the flow field covered an estimated 9.84 square kilometers by 8 November.

Geological summary: The 47-km-long wedge-shaped island of La Palma, the NW-most of the Canary Islands, is composed of two large volcanic centers. The older northern one is cut by the massive steep-walled Caldera Taburiente, one of several massive collapse scarps produced by edifice failure to the SW. The younger Cumbre Vieja, the southern volcano, is one of the most active in the Canaries. The elongated volcano dates back to about 125,000 years ago and is oriented N-S. Eruptions during the past 7,000 years have formed abundant cinder cones and craters along the axis of Cumbre Vieja, producing fissure-fed lava flows that descend steeply to the sea. Eruptions recorded since the 15th century have produced mild explosive activity and lava flows that damaged populated areas. The southern tip of the island is mantled by a broad lava field emplaced during the 1677-1678 eruption. Lava flows also reached the sea in 1585, 1646, 1712, 1949, and 1971.

Merapi, Central Java (Indonesia)

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

BPPTKG reported no morphological changes to Merapi’s SW lava dome, located just below the SW rim, and in the summit crater during 29 October-4 November. As many as 106 lava avalanches traveled a maximum of 2 km SW. One pyroclastic flow traveled 2 km SW. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-5 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

On 9 November Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that intense seismicity at Nevado del Ruiz had been recorded for the previous few weeks. Deformation data indicated minor changes. Low-temperature thermal anomalies were visible in satellite images during the previous week. Gas-and-steam emissions were sometimes visible in satellite data and webcam images rising as high as 1.9 km above the summit and drifting NE and E. These emissions sometimes contained ash; during 0735-0815 on 3 November an ash plume rose 1.4 km above the summit. Ash emissions on 7 November drifted W and NW, causing ashfall in Manizales and Villamar?a, both 25 km NW. The La Nubia airport temporarily suspended operations. The Alert Level remained at 3 (Yellow; the second lowest level on a four-color scale).

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.

Pavlof, United States

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

AVO reported that the eruption at Pavlof continued during 3-9 November and was focused at a vent on the upper NE flank. Seismicity remained elevated; several small explosions and discontinuous tremor were recorded during 5-8 November with increased frequency compared to the previous week. The explosions likely produced small, low-level ash plumes, though weather clouds often prevented confirmation by satellite and webcam images. Elevated surface temperatures were visible in satellite images overnight during 7-8 November, coincident with the emplacement of a 30-m-long lava flow. Small diffuse ash plumes were visible in webcam images and dissipated quickly. Elevated surface temperatures remained visible through 9 November. The Volcano Alert Level and Aviation Color Code remained at Watch and Orange, respectively.

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.

Semisopochnoi, Aleutian Islands (USA)

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

AVO reported that eruptive activity at Semisopochnoi's North Cerberus crater continued during 2-9 November. Daily tremor and minor explosions were detected in seismic and infrasound data. Several small low-level ash plumes were visible in webcam data rising to an estimated altitude of 1.5 (5,000 ft) a.s.l. during 2-3 November. Weather clouds obscured views during 4-7 November with the top of the cloud deck varying at altitudes of 3-6.1 km (10,000-20,000 ft) a.s.l.; ash plumes likely continued to be emitted though none rose above the cloud deck. Ash plumes were typically dissipating within 50 km of the volcano. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

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 a thermal anomaly over Sheveluch was identified in satellite images during 29 October-5 November. 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.

Suwanosejima, Ryukyu Islands (Japan)

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

JMA reported that seven explosions at Suwanosejima's Ontake Crater were recorded during 1-8 November. The explosions produced ash plumes that rose as high as 2 km above the crater rim and ejected material 300-600 m from the carter. Ashfall was reported in Toshima village (4 km SSW) during 1-5 November. The Alert Level remained at 3 and the public was warned to stay 2 km away from the crater.

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.

Taal, Luzon (Philippines)

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

PHIVOLCS reported that a series of volcanic earthquakes at Taal began at 0347 on 3 November and lasted for two minutes based on the seismic data; the events were felt at Intensity I in Banyaga, Agoncillo, and Batangas, and the largest event was a local M 2.9. The events were accompanied by a series of four short-lived plumes that rose less than 1 km above the lake. The characteristics of the seismic signals were similar to the phreatic bursts recorded in July. Upwelling hot volcanic fluids were visible in the crater lake during 3-9 November, and gas-and-steam plumes rose 0.9-1.8 km above the lake and drifted mainly SW. Sulfur dioxide emissions averaged 4,877-19,463 tonnes/day. Low-level background tremor continued along with as many as 111 volcanic earthquakes per day during 2-3 and 5-9 November and as many as 85 low-frequency volcanic earthquakes per day during 2-3 and 7-8 November. There were also 6-40 daily episodes of volcanic tremor, each lasting between 1 and 19 minutes. The Volcano Alert Level remained at a 2 (on a scale of 0-5). PHIVOLCS reminded the public that the entire Taal Volcano Island is a Permanent Danger Zone (PDZ) and that boating on Taal Lake was 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.

Telica, Nicaragua

12.606°N, 86.84°W, Summit elev. 1036 m

INETER reported that at 1650 on 28 October a small explosion from Telica produced an ash plume that rose 150 m above the crater rim and deposited ash on the NW flank. The event was followed by a small series of low-energy explosions that generated ash plumes that rose 300 m high and drifted N and NE. Minor ashfall was reported in Aguas Frías.

Geological summary: Telica, one of Nicaragua's most active volcanoes, has erupted frequently since the beginning of the Spanish era. This volcano group consists of several interlocking cones and vents with a general NW alignment. Sixteenth-century eruptions were reported at symmetrical Santa Clara volcano at the SW end of the group. However, its eroded and breached crater has been covered by forests throughout historical time, and these eruptions may have originated from Telica, whose upper slopes in contrast are unvegetated. The steep-sided cone of Telica is truncated by a 700-m-wide double crater; the southern crater, the source of recent eruptions, is 120 m deep. El Liston, immediately E, has several nested craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, SE of Telica, form a prominent geothermal area frequented by tourists, and geothermal exploration has occurred nearby.

Villarrica, Chile

39.42°S, 71.93°W, Summit elev. 2847 m

According to the Buenos Aires VAAC an ash plume from Villarrica rose to km (11,000 ft) a.s.l. and drifted SE on 6 November.

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.

Whakaari/White Island, North Island (New Zealand)

37.52°S, 177.18°E, Summit elev. 294 m

On 9 November GeoNet reported results from a recent overflight of Whakaari/White Island. Gas measurements showed that sulfur dioxide emissions had increased from 267 tons per day recorded on 14 October to 681 tonnes per day. Additionally, carbon dioxide increased from 757 to 2712 tonnes per day and hydrogen sulfide increased from 10 to 38 tonnes per day. The gas data suggested that a pulse of gas was rising from molten material at depth. Temperatures in the main vent area were as high as 252 degrees Celsius, similar to temperatures first measured in September and onward. Very minor ash emissions were visible and deposits only extended around the active vents. The lake had slightly deepened from recent rainfall. The Volcanic Alert Level remained at 2 and the Aviation Color Code remained at Yellow.

Geological summary: The uninhabited Whakaari/White Island is the 2 x 2.4 km emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes. The SE side of the crater is open at sea level, with the recent activity centered about 1 km from the shore close to the rear crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km NW. Descriptions of volcanism since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity there also forms a prominent part of Maori legends. The formation of many new vents during the 19th and 20th centuries caused rapid changes in crater floor topography. Collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining project. Explosive activity in December 2019 took place while tourists were present, resulting in many fatalities. The official government name Whakaari/White Island is a combination of the full Maori name of Te Puia o Whakaari ("The Dramatic Volcano") and White Island (referencing the constant steam plume) given by Captain James Cook in 1769.

Reference:

Smithsonian / US Geological Survey Weekly Volcanic Activity Report - 3 November-9 November 2021 - Managing Editor: Sally Kuhn Sennert


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