The Weekly Volcanic Activity Report: August 10 – 16, 2022
New activity/unrest was reported for 2 volcanoes from August 10 to 16, 2022. During the same period, ongoing activity was reported for 6 volcanoes.
New activity/unrest: Krysuvik-Trolladyngja, Reykjanes Peninsula | Ta’u, American Samoa (SW Pacific).
Ongoing activity: Aira, Kyushu (Japan) | Ebeko, Paramushir Island (Russia) | Great Sitkin, Andreanof Islands (USA) | Ibu, Halmahera | Kadovar, Northeast of New Guinea | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaiian Islands (USA) | Krakatau, Sunda Strait | Merapi, Central Java | Pavlof, Alaska Peninsula, Alaska | Popocatepetl, Mexico | Sangay, Ecuador | Semeru, Eastern Java | Sheveluch, Central Kamchatka (Russia) | Suwanosejima, Ryukyu Islands (Japan) | Taal, Luzon (Philippines).
Krysuvik-Trolladyngja, Reykjanes Peninsula
63.917°N, 22.067°W | Summit elev. 360 m
The fissure eruption in the Krýsuvík-Trölladyngja volcanic system that began on 3 August continued in the Meradalir valley during 10-16 August. Lava erupted mainly from a central cone and flowed ESE. According to the Institute of Earth Sciences the effusion rate had notably decreased, from an average of 11 cubic meters per second during 4-13 August to 3-4 cubic meters per second during 13-15 August. A news article stated that the effusion rate significantly decreased during 0530-0630 on 13 August based on information from IMO staff who were investigating the eruption site for new changes. The Institute of Earth Sciences estimated that 10.6 million cubic meters of lava had covered an area of 1.25 square kilometers by 15 August. Data collected during an overflight on 16 August indicated that the effusion rate had further reduced to 2 cubic meters per second during the previous day, though the uncertainty in that estimate was high. On 16 August residents reported seeing a purple-tinged sulfur dioxide gas cloud over the eruption area slowly drifting SW during sunrise.
Geological summary: The Krýsuvík-Trölladyngja volcanic system is described by the Catalogue of Icelandic Volcanoes as an approximately 50-km-long composite fissure swarm trending about N38°E, including a 30-km-long swarm of fissures, with no central volcano. It is one of the volcanic systems arranged en-echelon along the Reykjanes Peninsula west of Kleifarvatn lake. The Fagradalsfjall and Krýsuvík fissure swarms are considered splits or secondary swarms of the Krýsuvík–Trölladyngja volcanic system. Small shield volcanoes have produced a large portion of the erupted volume within the system. Several eruptions have taken place since the settlement of Iceland, including the eruption of a large basaltic lava flow from the Ogmundargigar crater row around the 12th century. The latest eruption, identified through tephrochronology, took place during the 14th century.
Ta’u, American Samoa (SW Pacific)
14.23°S, 169.454°W | Summit elev. 931 m
HVO reported that earthquakes were felt by residents of the Manu?a group of islands in American Samoa beginning on 26 July. Residents of Ofu and Olosega islands began reporting earthquakes on 10 August. Experts from HVO, Pago Pago National Weather Service Office (NWS), National Oceanic and Atmospheric Administration (NOAA) Pacific Tsunami Warning Center, NOAA-IOC (NOAA-Intergovernmental Oceanographic Commission), International Tsunami Information Center, and USGS National Earthquake Information Center have been working together to respond to the unrest. USGS scientists arrived on the islands and installed two microseismometers, one in Fiti?uta village on Ta?u island on 13 August and the other in Olosega village on 14 August. The instruments began recording about 20 earthquakes per hour. The largest earthquakes, including the felt events, were estimated to be between magnitudes 2 and 3; most of the events were too small to be felt. The exact location and depth of these earthquakes was unknown, due to limited earthquake monitoring equipment, though the data suggested that the events were beneath the Manu?a Islands, likely closer to Ta?u island rather than Ofu-Olosega, and were probably not related to the recently active Vailulu?u seamount. HVO noted that American Samoa’s volcanoes were monitored remotely by satellites and a distant seismic station in Apia, Samoa; the lack of ground-based monitoring stations does not allow for advanced warning of new activity. Both the Volcano Alert Level and Aviation Color Code were categorized as Unassigned due to the lack of a volcano-monitoring network.HVO reported that earthquakes were felt by residents of the Manu?a group of islands in American Samoa beginning on 26 July. Residents of Ofu and Olosega islands began reporting earthquakes on 10 August. Experts from HVO, Pago Pago National Weather Service Office (NWS), National Oceanic and Atmospheric Administration (NOAA) Pacific Tsunami Warning Center, NOAA-IOC (NOAA-Intergovernmental Oceanographic Commission), International Tsunami Information Center, and USGS National Earthquake Information Center have been working together to respond to the unrest. USGS scientists arrived on the islands and installed two microseismometers, one in Fiti?uta village on Ta?u island on 13 August and the other in Olosega village on 14 August. The instruments began recording about 20 earthquakes per hour. The largest earthquakes, including the felt events, were estimated to be between magnitudes 2 and 3; most of the events were too small to be felt. The exact location and depth of these earthquakes was unknown, due to limited earthquake monitoring equipment, though the data suggested that the events were beneath the Manu?a Islands, likely closer to Ta?u island rather than Ofu-Olosega, and were probably not related to the recently active Vailulu?u seamount. HVO noted that American Samoa’s volcanoes were monitored remotely by satellites and a distant seismic station in Apia, Samoa; the lack of ground-based monitoring stations does not allow for advanced warning of new activity. Both the Volcano Alert Level and Aviation Color Code were categorized as Unassigned due to the lack of a volcano-monitoring network.
Geological summary: The 10-km-wide Ta’u Island, located at the E end of the Samoan islands, is ringed by sea cliffs. It is the emergent portion of the large Lata shield volcano. A major flank collapse event around 22 ka resulted in the steep scarps on the southern side of the island. Two smaller shields were constructed along rift zones at the NW and NE tips of the island. The NW corner of the island has a tuff-cone complex that ejected large dunite xenoliths and coral blocks. Numerous Holocene post-caldera cones occur at the summit and on the flanks.
Aira, Kyushu (Japan)
31.593°N, 130.657°E | Summit elev. 1117 m
JMA reported that nighttime incandescence at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible during 8-15 August. The seismic network recorded 33 eruptive events and 12 explosions. Volcanic plumes rose as high as 2.5 km above the crater rim and material was ejected large ballistics as high as 1.7 km above the summit. 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
KVERT reported that moderate activity at Ebeko was ongoing. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions generated ash plumes that rose up to 3.5 km (11,500 ft) a.s.l. and drifted in multiple directions during 4-5 and 7-8 August. A thermal anomaly over the volcano was identified in satellite images during those same days. 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.
Great Sitkin, Andreanof Islands (USA)
52.076°N, 176.13°W | Summit elev. 1740 m
AVO reported that slow lava effusion at Great Sitkin continued during 9-16 August; no changes to the flow margins were visible but the lava had deepened around the vent. Weather clouds often obscured satellite and webcam views during most of the week. Seismicity was low and occasional local earthquakes were recorded. Elevated surface temperatures were identified in satellite images on most days. 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.
1.488°N, 127.63°E | Summit elev. 1325 m
PVMBG reported that the eruption at Ibu continued during 9-16 August. Gray-and-white ash plumes of variable densities generally rose as high as 1.5 km above the summit and drifted in multiple directions. 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, Northeast of 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 14 August an ash plume from Kadovar rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted NW.
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.
Karymsky, Eastern Kamchatka (Russia)
54.049°N, 159.443°E | Summit elev. 1513 m
KVERT reported that the eruption at Karymsky continued during 4-11 August. A daily thermal anomaly over the volcano was identified in satellite images. Explosions during 5-9 August produced ash plumes that rose as high as 5 km (16,400 ft) a.s.l. and drifted 550 km in multiple directions. 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: 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.
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 9-16 August, entering the lava lake and flowing onto the crater floor. Part of the lake was continuously active. The lake level mostly remained within the bounding levees, though daily breakouts were visible along the margins. 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.
Krakatau, Sunda Strait
6.102°S, 105.423°E | Summit elev. 155 m
PVMBG reported that cloudy weather often prevented visual confirmation of the ongoing eruption at Anak Krakatau during 9-16 August. Incandescence at or near the vent was seen in nighttime photos on most days. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay at least 5 km away 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 edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of that 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 caused more than 36,000 fatalities, most as a result of 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.
Merapi, Central Java
7.54°S, 110.446°E | Summit elev. 2910 m
BPPTKG reported that the eruption at Merapi continued during 5-11 August and seismicity remained at high levels. As many as 43 lava avalanches traveled down the Bebeng drainage on the SW flank, reaching a maximum distance of 1.5 km. 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 9-16 August, though cloud cover often prevented visual confirmation. Seismic tremor persisted and multiple small daily explosions were detected in local and regional seismic and infrasound data. The explosions may have produced minor ash emissions that rose no higher than 3 km (10,000 ft) a.s.l. and dissipated quickly, though on a few of the clear views none were seen. Elevated surface temperatures were identified in satellite images on most of the days. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.
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.
19.023°N, 98.622°W | Summit elev. 5393 m
CENAPRED reported that there were 19-204 steam-and-gas emissions, sometimes containing minor amounts of ash, rising from Popocatépetl each day during 9-16 August. A minor explosion was recorded at 0839 on 10 August and a moderate explosion was detected at 1528 on 11 August. Minor ashfall was reported in the municipality of Ecatzingo, State of Mexico. An explosion at 1952 on 13 August was followed at 2125 by minor amounts of ashfall in Tetela del Volcán. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale).
Geological summary: Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America’s 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.
2.005°S, 78.341°W | Summit elev. 5286 m
IG reported that a notable increase in seismicity at Sangay began at around 1000 on 12 August and was followed by the effusion of a lava flow that descended more than 1 km on the SE flank. Strombolian activity was visible at the summit. Ash plumes rose as high as 3.5 km above the summit and drifted 500 km W and SW, past the coastline, and caused daily ashfall in the provinces of Chimborazo and Guayas during 12-16 August. The Guayaquil International Airport canceled several commercial flights on 13 August due to the presence of ash in the atmosphere. Seismicity decreased to previous levels by 16 August.
Geological summary: The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador’s volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex.
Semeru, Eastern Java
8.108°S, 112.922°E | Summit elev. 3657 m
The eruption at Semeru continued during 10-16 August. The Darwin VAAC reported that during 13-16 August ash plumes rose to altitudes of 4.3-4.6 km (14,000-15,000 ft) a.s.l. and drifted SW and W based on satellite images and wind models. 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.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E | Summit elev. 3283 m
KVERT reported that the ongoing eruption at Sheveluch was characterized by explosions, hot avalanches, and lava-dome extrusion during 4-11 August. A daily thermal anomaly was identified in satellite images, and gas-and-steam plumes containing some ash were visible drifting 70 km E and SE during 8-9 August. 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 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 the number of daily explosions at Suwanosejima’s Ontake Crater began increasing on 2 August and remained elevated through 7 August; their frequency began decreasing on 8 August. About 11 explosions were recorded during 8-15 August. Eruption plumes rose as high as 2 km above the crater rim and large ballistics were ejected as far as 800 m from the crater. Incandescence from the crater was often visible at night. 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, 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 sulfur dioxide emissions at Taal averaged 3,802-6,844 tonnes per day during 9-10 and 12-15 August; a high of 13,572 tonnes per day was recorded on 11 August causing significant vog around the caldera and a sulfur odor reported by residents of Banyaga, (Agoncillo), Poblacion 5, Boso-boso, and Gulod (Laurel), and Poblacion (Talisay). Upwelling volcanic gasses and fluids in the lake were visible, along with voluminous steam-rich plumes that rose as high as 3 km above the lake and drifted mainly NE, SE, and SW. The Alert Level remained at 1 (on a scale of 0-5), and PHIVOLCS reminded the public that the entire Taal Volcano Island was a Permanent Danger Zone (PDZ).
Geological summary: Taal is one of the most active volcanoes in the Philippines and has produced some 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 observed eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones. Powerful pyroclastic flows and surges have caused many fatalities.
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, August 10 – 16, 2022 – Managing Editor: Sally Kuhn Sennert
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