The Weekly Volcanic Activity Report: November 10 - 16, 2021

The Weekly Volcanic Activity Report: November 10 - 16, 2021

New activity/unrest was reported for 2 volcanoes from November 10 to 16, 2021. During the same period, ongoing activity was reported for 15 volcanoes.

New activity/unrest: Karymsky, Eastern Kamchatka (Russia) | Turrialba, Costa Rica.

Ongoing activity: Aira, Kyushu (Japan) | Ebeko, Paramushir Island (Russia) | Fernandina, Ecuador | Fukutoku-Oka-no-Ba, Volcano Islands (Japan) | Great Sitkin, Andreanof Islands (USA) | Ibu, Halmahera (Indonesia) | Kadovar, Papua New Guinea | Kilauea, Hawaiian Islands (USA) | La Palma, Spain | Merapi, Central Java (Indonesia) | Pavlof, United States | Semisopochnoi, Aleutian Islands (USA) | Sheveluch, Central Kamchatka (Russia) | Stromboli, Aeolian Islands (Italy) | Taal, Luzon (Philippines).

New activity/unrest

Karymsky, Eastern Kamchatka (Russia)

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

KVERT reported that during 8-12 November explosions at Karymsky generated ash plumes that rose as high as 5.5 km (18,000 ft) a.s.l. and drifted 300 km E and SE. A thermal anomaly was visible in satellite images. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

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.

Turrialba, Costa Rica

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

OVSICORI-UNA reported that on 11 November a small area of incandescence was visible on the internal SW wall of Turrialba’s summit vent. Vigorous degassing from the vent was recorded.

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 8-15 November. Very small eruptions were recorded. 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 each day during 5-9 November produced ash plumes that rose as high as 2.3 km (7,500 ft) a.s.l. and drifted SE and E. 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.

Fernandina, Ecuador

0.37°S, 91.55°W, Summit elev. 1476 m

IG reported that slow deformation at Fernandina has been recorded over the previous 18 months. InSAR data showed that inflation was occurring at a rate of about 400 mm/year in the summit caldera and on the NE flank, while deflation was occurring at a rate of about 100-400 mm/year in areas on the upper W and SW flanks. On 13 October the areas of deflation changed to inflation and the rate of deformation in the caldera increased. On 17 November IG noted that fumarolic activity in the summit crater was visible during the previous few days and may have been related to a small episode of tremor on 16 November. IG also noted that periodic fumarolic activity and small episodes of tremor are common at Fernandina without an eruption.

Geological summary: Fernandina, the most active of Galápagos volcanoes and the one closest to the Galápagos mantle plume, is a basaltic shield volcano with a deep 5 x 6.5 km summit caldera. The volcano displays the classic "overturned soup bowl" profile of Galápagos shield volcanoes. Its caldera is elongated in a NW-SE direction and formed during several episodes of collapse. Circumferential fissures surround the caldera and were instrumental in growth of the volcano. Reporting has been poor in this uninhabited western end of the archipelago, and even a 1981 eruption was not witnessed at the time. In 1968 the caldera floor dropped 350 m following a major explosive eruption. Subsequent eruptions, mostly from vents located on or near the caldera boundary faults, have produced lava flows inside the caldera as well as those in 1995 that reached the coast from a SW-flank vent. Collapse of a nearly 1 km3 section of the east caldera wall during an eruption in 1988 produced a debris-avalanche deposit that covered much of the caldera floor and absorbed the caldera lake.

Fukutoku-Oka-no-Ba, Volcano Islands (Japan)

24.285°N, 141.481°E, Summit elev. -29 m

The Japan Coast Guard reported that during an 11 November overflight of Fukutoku-Oka-no-Ba, observers noted that the size of the W island was mainly unchanged. White fumarolic plumes rose from the N end of the island and bubbling was seen on the ocean surface near the N end.

Geological summary: Fukutoku-Oka-no-ba is a submarine volcano located 5 km NE of the pyramidal island of Minami-Ioto. Water discoloration is frequently observed from the volcano, and several ephemeral islands have formed in the 20th century. The first of these formed Shin-Ioto ("New Sulfur Island") in 1904, and the most recent island was formed in 1986. The volcano is part of an elongated edifice with two major topographic highs trending NNW-SSE, and is a trachyandesitic volcano geochemically similar to Ioto.

Great Sitkin, Andreanof Islands (USA)

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

AVO reported that lava effusion at Great Sitkin continued during 10-16 November. Elevated surface temperatures were visible in clear satellite images during 11 and 15-16 November. Two days later effusion was confirmed in satellite images; the N lava flow had not progressed but the W and S flank flows had advanced to 680 and 650 m, respectively. 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.

Ibu, Halmahera (Indonesia)

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

PVMBG reported that during 10-11 and 14-16 November gray-and-white ash plumes from Ibu rose 200-800 m above the summit. During 10-11 November the ash plumes drifted S and W, causing minor ashfall in villages to the W. The Alert Level remained at a 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater and 3.5 km away on the N side.

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

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 9 November an ash plume from Kadovar rose to an altitude of 1.5 km (5,000 ft) a.s.l.

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 at a vent in the lower W wall of Halema`uma`u Crater. By 9 November the total volume of erupted lava was an estimated 27 million cubic meters. The sulfur dioxide emission rate was 2,600 tonnes per day on 9 November. Spatter and ponded lava in the vent were visible during 9-16 November; lava entered the lake through a short channel in the E part of the W wall cone, feeding the lake which had risen 60 m since 29 September. The active area of the lava lake had increased during the week. 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 10-16 November, characterized by Strombolian explosions and lava fountaining from multiple vents, advancing and sometimes branching lava flows, and daily ash emissions. Eruption details are based on official sources including daily PEVOLCA (Plan de Emergencias Volcánicas de Canarias) steering committee summaries. Volcanic tremor levels continued to be low. Seismicity at intermediate depths of 10-15 km remained low compared to previous weeks. The number and magnitude of deeper events, 20-38 km deep, increased during 9-11 with the highest number of deeper events recorded since the beginning of the eruption; the rate of deeper events decreased during 11-12 November. Two M 5 earthquakes were the largest events recorded during the week, occurring at 0447 on 11 November at a depth of 30 km and at 0756 on 13 November at a depth of 38 km.

Several vents in the main cone continued to effuse lava, eject tephra, and emit ash-and-gas plumes. The activity levels varied in intensity, though decreased overall during the week. By 10 November the highest point of the main cone was 1,130 m a.s.l. Lava continued to flow west through pre-existing lava channels and tubes, over older flows, and occasionally formed new branches. Occasional short-lived overflows of lava ponds occurred at the main crater vents. The flow field was made up of overlapping flows numbered 1-11. Lava filled in some gaps between the N flows, numbers 4 and 7, though lava-flow advancement was mainly focused at and near the ocean entries, with lava feeding flows 1, 2, and 9. The first flow, number 1, had previously reached the sea, and flow 9 had stalled before reaching the coast. Flow number 2 (in between 1 and 9) had reached the sea at Los Guirres Beach on 9 November, and sent a new branch N that entered the ocean at 0144 on 10 November. Flow 2 continued to advance during the week, filling in gaps between flows 1 and 9, and adding to the new lava delta laterally. Areas of high turbidity in the water column as far as 1 km from the lava front were caused by underwater lava advancement. By 16 November the width of the flow field had grown to 3.2 km.

Sulfur dioxide emissions fluctuated at high levels between 7,000 and 43,000 tons per day on most days, but was as low as 2,000-4,000 tons per day on 13 and 15 November. Sometimes dense and billowing ash-and-gas plumes rose 1.8-3.1 km (5,900-10,200 ft) a.s.l. and drifted in multiple directions. Ash emissions intensified on 14 November. Clean-up of ash from streets and homes was conducted by both authorities and residents. According to a news report a resident that was granted permission to enter the exclusion zone to clean ash off of his roof died in the neighborhood of Corazoncillo of unknown causes. Fresh ash emissions from the volcano, and ash resuspended by people and vehicle movements, triggered a few air-quality alerts issued during 14-16 November; authorities warned residents of some affected areas (Los Llanos de Aridane, Tazacorte, El Paso, Puntagorda, and Tijarafe) to stay indoors. On 16 November ash drifted W and SW and caused some flight disruptions at the La Palma airport.

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 notable morphological changes to Merapi’s SW lava dome, located just below the SW rim, or in the summit crater during 5-11 November. As many as 123 lava avalanches traveled a maximum of 2 km SW. Two pyroclastic flows traveled 1.5-2 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.

Pavlof, United States

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

AVO reported that the eruption at Pavlof continued during 10-16 November and was focused at a vent on the upper NE flank. Seismicity remained elevated. Pilots observed steam plumes rising to 4.3 km (14,000 ft) a.s.l.; steam plumes were also visible the next day. On 11 November a narrow 2-km-long lahar deposit on the SE flank was identified in satellite images. The lahar was likely generated by the interaction of lava and snow on the upper flank. Strongly elevated surface temperatures visible in satellite images during 10-15 November were indicative of lava effusion and possibly fountaining. Several explosions were recorded during 12-14 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 10-16 November. Daily minor explosions were detected in seismic and infrasound data. Daily ash plumes were visible in webcam and satellite data rising to 1.5-3.7 (5,000-12,000 ft) a.s.l., drifting NE, E, SE, and S, and dissipated quickly. Weather clouds sometimes obscured views. Ash plumes were typically dissipating within 50 km of the volcano. Minor ashfall on the island was sometimes visible. 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 5-12 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.

Stromboli, Aeolian Islands (Italy)

38.789°N, 15.213°E, Summit elev. 924 m

INGV reported that during 8-14 November activity at Stromboli was characterized by ongoing explosive activity from five vents in Area N (North Crater area) and four vents in Area C-S (South-Central Crater area). Sometimes weather conditions prevented visual confirmation with webcams. Explosions from two vents in the N1 vent (Area N) ejected lapilli and bombs 80 m high. Short periods of spattering at the vent overlooking the Sciara del Fuoco was sometimes observed and intensified on 8 and 12 November. Explosions at three N2 vents (Area N) averaged 10-15 events per hour and ejected material 80-150 m high. Sometimes intense spattering was recorded during 8-9 and 14 November. No explosions occurred at S1 and C vents in Area C-S; explosions at the two S2 vents occurred at a rate of 6-7 per hour and ejected coarse material as high as 80 m high.

Geological summary: Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5,000 years ago due to a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium.

Taal, Luzon (Philippines)

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

Three short (1-3 minutes) phreatomagmatic bursts at Taal were recorded at 2339 on 15 November, and at both 0146 and 0254 on 17 November. The first generated a plume that rose 2.4 km and drifted SW and the next two events generated plumes that rose 400-500 m based on thermal camera images. PHIVOLCS stated that the events were likely driven by fracturing and gas release from magma beneath the Taal Volcano Island.

Sulfur dioxide emissions averaged 9,448-12,516 tonnes/day during 10-16 November. Upwelling hot volcanic fluids were visible in the crater lake, and daily gas-and-steam plumes rose 0.7-1.5 km above the lake and drifted mainly SW. Low-level background tremor continued to be recorded. During 9-12 November the seismic network recorded 135-223 volcanic earthquakes per day, and as many as 72 low-frequency volcanic earthquakes per day, and 70-180 daily episodes of volcanic tremor, each lasting 1-3 minutes. Three hybrid earthquakes were recorded during 9-10 November. No earthquakes were detected during 12-13 November. Seismicity then increased during 14-16 November with a few periods of tremor (1-3 minutes long), 9-10 daily volcanic earthquakes, and 3-4 daily low-frequency volcanic earthquakes. 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.

Reference:

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 October-3 November 2020 - Managing Editor: Sally Kuhn Sennert


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