The Weekly Volcanic Activity Report: August 3 - 9, 2022

New activity/unrest was reported for 4 volcanoes from August 3 to 9, 2022. During the same period, ongoing activity was reported for 17 volcanoes.

New activity/unrest: Aira, Kyushu (Japan) | Grimsvotn, Iceland | Ioto, Volcano Islands | Krysuvik-Trolladyngja, Reykjanes Peninsula.

New activity/unrest

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 1-8 August. The seismic network recorded 25 eruptive events and seven explosions. Volcanic plumes rose as high as 2.8 km above the crater rim and material was ejected material as high as 1.3 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.

Grimsvotn, Iceland

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

The Icelandic Meteorological Office (IMO) reported that seismicity at Grímsvötn had declined to normal levels during the past few days, and no significant variations from background levels were observed in geochemical or deformation data. On 9 August the Aviation Color Code was lowered to Green.

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

Ioto, Volcano Islands

24.751°N, 141.289°E | Summit elev. 169 m

JMA reported that minor eruptive activity off the coast at Ioto (Iwo-jima) had been visible daily during 11-31 July. On 14 July pumice pieces from the eruption washed up onto the shore at Onohama and were photographed during a field survey conducted by the National Research Institute for Earth Science and Disaster Prevention. JMA scientist visited the site on 31 July and confirmed the pumice deposits on the beach. They saw eruptive activity every few minutes, and gray, tephra-laden columns of water being ejected 20-30 m above the ocean’s surface. A satellite image on 4 August showed a small rounded gray zone at the water surface and a plume of discolored water drifting NE.

Geological summary: Ioto in the central Volcano Islands portion of the Izu-Marianas arc lies within a 9-km-wide submarine caldera. Ioto, Iwojima, and Iojima are among many transliterations of the name. The volcano is also known as Ogasawara-Iojima to distinguish it from several other “Sulfur Island” volcanoes in Japan. The triangular, low-elevation, 8-km-long island narrows toward its SW tip and has produced trachyandesitic and trachytic rocks that are more alkalic than those of other Izu-Marianas arc volcanoes. The island has undergone dramatic uplift for at least the past 700 years accompanying resurgent doming of the caldera. A shoreline landed upon by Captain Cook’s surveying crew in 1779 is now 40 m above sea level. The Motoyama plateau on the NE half of the island consists of submarine tuffs overlain by coral deposits and forms the island’s high point. Many fumaroles are oriented along a NE-SW zone cutting through Motoyama. Numerous historical phreatic eruptions, many from vents on the west and NW sides of the island, have accompanied the remarkable uplift.

Krysuvik-Trolladyngja, Reykjanes Peninsula

63.917°N, 22.067°W | Summit elev. 360 m

The fissure eruption of the Krýsuvík-Trölladyngja volcanic system that began at around 1318 on 3 August continued at least through 9 August. Numerous small lava fountains rose along the fissure, located near the border of the previous flow field N of Fagradalsfjall, and lava flows traveled downslope to the NW. Scientists from the Institute of Earth Sciences stated that the initial flow rate was 5-10 times greater than the flow rate at the start of the 2021 eruption, based on model estimates, field data, and satellite measurements. The flow rate was about 32 cubic meters per second during the initial hours of the eruption, then decreased to an average of 18 cubic meters per second from 1700 on 3 August until 1100 on 4 August, by which time about 1.6 million cubic meters of lava had covered an area of 0.14 square kilometers. The average flow thickness was around 11 m. According to a news article the length of the active fissure had decreased and the middle part of the fissure was the most active. On 5 August Icelandic Meteorological Office (IMO) reported that the number of daily earthquakes declined after the eruption began and deformation stabilized. Thousands of people were walking on the trails to view the eruption; authorities warned the public to heed inclement weather warnings, and closed access to the site during 7-9 August due to weather conditions and trail maintenance.

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.

Ongoing activity

Ebeko, Paramushir Island (Russia)

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

KVERT reported that moderate activity at Ebeko was ongoing during 28 July-4 August. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions generated ash plumes that rose up to 4.5 km (14,800 ft) a.s.l. and drifted in multiple directions. A thermal anomaly over the volcano was identified in satellite images during 1 and 3-4 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 flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Fuego, South-Central Guatemala

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

INSIVUMEH reported that 3-10 explosions per hour were recorded at Fuego during 2-9 August, generating ash plumes that rose as high as 1.1 km above the crater rim. The ash plumes drifted as far as 30 km W and SW, causing daily ashfall in areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Los Yucales (12 km SW), Sangre de Cristo (8 km WSW), El Porvenir (8 km ENE), San Pedro Yepocapa (8 km NW), Ojo de Agua, and Finca Palo Verde. Daily shock waves rattled structures in communities around the volcano and rumbling was occasionally heard. Daily block avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Honda, and Las Lajas (SE) drainages. Explosions ejected incandescent material 100-300 m above the summit each day.

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

Great Sitkin, Andreanof Islands (USA)

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

AVO reported that slow lava effusion at Great Sitkin likely continued during 2-9 August; no changes to the flow lengths were visible but the lava had deepened around the vent. Weather clouds often obscured satellite and webcam views during most of the week, though no activity was visible when views were clear. Seismicity was low and occasional local earthquakes were recorded. Elevated surface temperatures were identified in satellite images during 5-9 August. 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.

Karymsky, Eastern Kamchatka (Russia)

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

KVERT reported that the eruption at Karymsky continued during 29 July-4 August. Explosions during 29-31 July, 1-2 August, and 4 August produced ash plumes that rose 4-8 km (13,100-26,200 ft) a.s.l. and drifted 230 km S, SE, and E. A thermal anomaly over the volcano was identified in satellite images during 31 July-4 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: 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 2-9 August, entering the lava lake and flowing onto the crater floor. The lake level remained within the bounding levees. Daily minor ooze-outs were visible along the margins of the crater floor. Intense incandescence from the W vent was visible during 5-9 August. 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 the eruption at Anak Krakatau continued during 3-9 August. Several eruptive events occurred on 3 August (at 0034, 0115, and 1540), sometimes producing dense black ash plumes that rose as high as 1.5 km above the summit and drifted SW. At 0926 on 4 August a dense gray-to-black ash plume rose 1.5 km and drifted N. Incandescence at or near the vent was seen in nighttime photos on most days. Diffuse white plumes were visible rising from the volcano during 7-8 August. 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.

Lewotolok, Lembata Island

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

PVMBG reported that the Strombolian eruption at Lewotolok continued during 2-9 August. Daily white or white-and-gray emissions rose as high as 400 m above the summit and drifted in multiple directions. Photos in some posted reports showed Strombolian activity. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater and 4 km away from the crater on the SE flank.

Geological summary: The Lewotolok (or Lewotolo) stratovolcano occupies the eastern end of an elongated peninsula extending north into the Flores Sea, connected to Lembata (formerly Lomblen) Island by a narrow isthmus. It is symmetrical when viewed from the north and east. A small cone with a 130-m-wide crater constructed at the SE side of a larger crater forms the volcano’s high point. Many lava flows have reached the coastline. Eruptions recorded since 1660 have consisted of explosive activity from the summit crater.

Merapi, Central Java

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

BPPTKG reported that the eruption at Merapi continued during 29 July-4 August. Seismicity remained at high levels. As many as 34 lava avalanches traveled down the Bebeng drainage on the SW flank, reaching a maximum distance of 1.8 km. The volumes of both the SW and central lava domes were unchanged based on photo analyses. 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.

Nevado del Ruiz, Colombia

4.892°N, 75.324°W | Summit elev. 5279 m

On 2 August Servicio Geológico Colombiano’s (SGC) reported that during the previous week the number and size of seismic signals indicating fluid movement had increased at Nevado del Ruiz compared to the week before, though they remained at moderate levels. Although seismic signals indicating rock fracturing increased in number, magnitudes were similar to the previous week. Several episodes of drumbeat seismicity were recorded, indicating continuing growth of the lava dome. Gas-and-steam emissions rose from the crater, reaching just over 2.4 km above the summit on 30 July. Several thermal anomalies in Arenas Crater were identified in satellite images during 0500-0600 on 4 August, and seismic signals indicating emissions were recorded during 4-5 August. Ashfall was reported in the municipalities of Santa Rosa de Cabal, Pereira, Villamaría, Manizales, and Dosquebradas. Tephra deposits were visible near the crater and in areas up to 3 km away. 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, 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 3-9 August. Seismic tremor persisted and multiple daily explosions were detected in local and regional seismic and infrasound data. The explosions likely produced minor ash emissions that rose no higher than 3 km (10,000 ft) a.s.l., though cloud cover prevented confirmation on most days. Strongly elevated surface temperatures were identified in satellite images during 7-8 August. 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.

Sabancaya, Peru

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

Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 1-7 August with a daily average of 19 explosions. Gas-and-ash plumes rose as high as 2.7 km above the summit and drifted E, SE, SW, and W. As many as seven thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. Minor inflation continued to be detected near Hualca Hualca (4 km N). The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 12-km radius.

Geological summary: Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning “tongue of fire” in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.

Santa Maria, Southwestern Guatemala

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

INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 2-9 August. Lava flows continued to advance in the San Isidro and El Tambor drainages on the W and SW flanks and were as long as 3.7 km by 5 August. Block avalanches from the W part of Caliente cone, and from both the ends and sides of the flows descended the S, SW, and W flanks. The avalanches generated ash plumes that rose about 1 km and drifted SW, S, and E, causing ashfall in areas downwind including La Florida, Monte Claro, San Marcos Palajunoj, Loma Linda, and Las Marías. Incandescence from Caliente cone and the lava-flow fronts was sometimes visible at night.

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

Semeru, Eastern Java

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

PVMBG reported that the eruption at Semeru continued during 3-9 August. Eruptive events recorded at 0810 on 3 August, 0628 on 4 August, 1245 on 5 August, and 0720 on 6 August produced ash plumes that rose 500-700 m above the summit and drifted SW and N. 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 29 July-4 August. A daily thermal anomaly was identified in satellite images, and ash plumes were visible drifting 24 km SW on 31 July. 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.

Stromboli, Aeolian Islands (Italy)

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

INGV reported that during 1-7 August activity at Stromboli was characterized by ongoing explosions from two vents in Area N (North Crater area) and two vents in Area C-S (South-Central Crater area). Low-intensity explosions from the N1 vent (Area N) ejected mostly ash, with some course material, 80-150 m high at a rate of 2-6 explosions per hour. The N2 vent (Area N) emitted gases. No explosions occurred at the S1 and C vents in Area C-S; low-intensity explosions at two S2 vents ejected coarse material 80-150 m high at a rate of 3-4 explosions per hour.

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.

Suwanosejima, Ryukyu Islands (Japan)

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

JMA reported that the number of explosions at Suwanosejima’s Ontake Crater increased during 2-8 August, when around 30 were recorded; nine of those were detected on 7 August. During 7-8 August eruption plumes rose as high as 2 km above the crater rim and mingled with weather clouds. Large ballistics were ejected 600 m from the crater’s center. Incandescence from the crater was 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 increases in both sulfur dioxide emissions at Taal and activity in Main Crater Lake. Sulfur dioxide emissions averaged 1,289 tonnes per day from May to mid-June, and increased to an average of 4,952 tonnes per day during 15 July-3 August. Sulfur dioxide emissions further increased to 12,125 and 17,141 tonnes per day on 3 and 7 August, respectively, prompting PHIVOLCS to issue advisories. Vog was present over the W part of Taal Caldera during 2-3 August; dense vog in Laurel and Banyaga (Agoncillo, Batangas Province) also damaged vegetation. A sulfur odor was reported by residents of Tagaytay City and Bugaan East. Upwelling gasses and hot fluids in the lake, and voluminous steam-rich plumes rising as high as 2.8 km above the lake, were visible during 1-9 August. Recent low-frequency seismic events and tremor were characterized as above background. 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 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 August 3 -9, 2022 – Managing Editor: Sally Kuhn Sennert

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