The Weekly Volcanic Activity Report: June 8 – 14, 2022

the weekly volcanic activity report

New activity/unrest was reported for 2 volcanoes from June 8 to 14, 2022. During the same period, ongoing activity was reported for 17 volcanoes.

New activity/unrest: Bulusan, Luzon (Philippines)  | Krakatau, Sunda Strait.

Ongoing activity: Aira, Kyushu (Japan)  | Bezymianny, Central Kamchatka (Russia)  | Dukono, Halmahera  | Erta Ale, Ethiopia  | Etna, Sicily (Italy)  | Great Sitkin, Andreanof Islands (USA)  | Karymsky, Eastern Kamchatka (Russia)  | Kilauea, Hawaiian Islands (USA)  | Lewotolok, Lembata Island  | Merapi, Central Java  | Pavlof, Alaska Peninsula, Alaska  | Popocatepetl, Mexico  | Ruapehu, North Island (New Zealand)  | Semeru, Eastern Java  | Semisopochnoi, Aleutian Islands (USA)  | Sheveluch, Central Kamchatka (Russia)  | Suwanosejima, Ryukyu Islands (Japan).

New activity/unrest

Bulusan, Luzon (Philippines)

12.769°N, 124.056°E  | Summit elev. 1535 m

PHIVOLCS reported that increased seismicity at Bulusan began at 0500 on 9 June, characterized by a total of 45 volcanic earthquakes, including two low-frequency events. Most of the events were low magnitude and shallow. A phreatic eruption was detected at 0337 on 12 June. Plumes were not visible in webcam images due to darkness, but residents of Inlagadian (Casiguran municipality) briefly saw incandescence at the base of a plume. In data from seismic and infrasound instruments the event was classified as an explosion-type earthquake which lasted about 18 minutes. An explosion was felt by residents within 5 km, including in the barangays of Añog (Juban) and Inlagadian. Rumbling was heard in Sitio Bagong Barrio, and in barangays of Santa Lourdes (Barcelona), Inlagadian and San Juan (Casiguran), Bentuco (Gubat), and Añog, Calateo, and Puting Sapa (Juban). Sporadic ash emissions began to be observed at 0430. At daybreak emissions were visible rising from six vents: Blackbird Crater (the main crater), three explosion pits in the summit crater, and two vents on the NW and N sides of the summit. Steam, gas, and ash plumes rose 400-750 m above the summit and drifted several kilometers NW. Ash carried by winds fell in areas as far as 50 km NW, in Sorsogon City and Palanas, Pilar, Sorsogon Province, across Sorsogon Bay, and as far as Anislag, Daraga, Albay. Ash on the upper NW flanks was visible, and several barangays in the municipalities of Casiguran, Juban, and Magallanes experienced minor ashfall. Emissions continued throughout the day. According to a news article more than 11,000 people (at least 2,800 families) in Juban evacuated, and flights in and out of the Bicol International Airport were cancelled. The Alert Level remained at 1 (on a scale of 0-5) and PHIVOLCS reminded the public not to enter the 4-km-radius Permanent Danger Zone (PDZ) nor the 2 km Extended Danger Zone (EDZ) on the SE flank. After the eruption gas emissions rose from the main crater and, for the first time this year, from the NW summit vent.

Geological summary: Luzon’s southernmost volcano, Bulusan, was constructed along the rim of the 11-km-diameter dacitic-to-rhyolitic Irosin caldera, which was formed about 36,000 years ago. It lies at the SE end of the Bicol volcanic arc occupying the peninsula of the same name that forms the elongated SE tip of Luzon. A broad, flat moat is located below the topographically prominent SW rim of Irosin caldera; the NE rim is buried by the andesitic complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded since the mid-19th century.

Krakatau, Sunda Strait

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

PVMBG reported that an eruptive event at Anak Krakatau was recorded at 1159 on 8 June, producing a dense white-to-gray ash plume that rose about 500 m above the summit and drifted SW. At 1304 a dense gray ash plume rose around 500 m and drifted S. 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 Krakatau edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.

Ongoing activity

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 6-13 June. Very small eruptive events were recorded during 6-10 June. 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.

Bezymianny, Central Kamchatka (Russia)

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

KVERT reported that eruptive activity at Bezymianny was characterized by strong fumarolic emissions, lava-dome incandescence, and hot avalanches continued during 4-9 June. A daily thermal anomaly was identified in satellite images. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Geological summary: Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Dukono, Halmahera

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

Based on satellite and wind model data, the Darwin VAAC reported that during 8-14 June ash plumes from Dukono rose to 2.1 km (7,000 ft) a.s.l. and drifted NW, W, and SW. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Geological summary: Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia’s most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

Erta Ale, Ethiopia

13.6°N, 40.67°E  | Summit elev. 613 m

On 2, 7, and 12 June infrared satellite data showed two thermal anomalies of variable intensities in Erta Ale’s S pit crater.

Geological summary: The Erta Ale basaltic shield volcano is the most active in Ethiopia, with a 50-km-wide edifice that rises more than 600 m from below sea level in the barren Danakil depression. It is the namesake and most prominent feature of the Erta Ale Range. The volcano includes a 0.7 x 1.6 km elliptical summit crater hosting steep-sided pit craters. Another larger 1.8 x 3.1 km wide depression elongated parallel to the trend of the Erta Ale range is located SE of the summit and is bounded by curvilinear fault scarps on the SE side. Fresh-looking basaltic lava flows from these fissures have poured into the caldera and locally overflowed its rim. The summit caldera usually also holds at least one long-term lava lake that has been active since at least 1967, or possibly since 1906. Recent fissure eruptions have occurred on the N flank.

Etna, Sicily (Italy)

37.748°N, 14.999°E  | Summit elev. 3357 m

INGV reported that during 6-12 June explosive activity at Etna’s Southeast Crater (SEC) produced sporadic and minor ash emissions that rapidly dispersed. The fissure located at the upper part of the Valle del Bove, between 2,700 and 2,900 m elevation, continued to produce lava flows at a variable rate. The flows were most active between 2,000 and 2,100 m elevation but overall were visibly cooling during the week. Flows from the fissure that had opened on 7 June at the base of the N wall of the Valle del Bove, at 1,979 m elevation, had traveled 170 m and were also cooling. A new fissure with three active vents opened on 11 June around 1,900 m elevation. Lava effusion was slow, and the flow only traveled a few tens of meters.

Geological summary: Mount Etna, towering above Catania on the island of Sicily, has one of the world’s longest documented records of volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Great Sitkin, Andreanof Islands (USA)

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

AVO reported that the eruption at Great Sitkin continued during 8-14 June. Elevated surface temperatures were identified in satellite data almost daily, consistent with lava effusion. Seismicity was low. 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 a thermal anomaly over Karymsky was identified in satellite images during 4-9 June. 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 8-14 June, entering the lava lake and flowing onto the crater floor. The surface of the lava lake was continuously active all week, and the lake level was relatively stable. Nearly-continuous breakouts of lava occurred along the margins of the lake. The sulfur dioxide emission rate was approximately 1,900 and 1,350 tonnes per day on 8 and 10 June, respectively. 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.

Lewotolok, Lembata Island

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

PVMBG reported that the eruption at Lewotolok continued during 8-14 June. Daily white-and-gray emissions rose as high as 1 km above the summit and drifted in multiple directions. The summit crater was often incandescent, and a 200-m-long lava flow was active W of the summit. 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 3-9 June. The heights and morphologies of the SW lava dome and the central lava dome were unchanged from the previous week, and seismicity remained at high levels. As many as 75 lava avalanches, reaching a maximum distance of 2 km, traveled down the Bebeng drainage on the SW flank. Seismicity remained high. 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 the eruption at a vent on Pavlof’s upper E flank was ongoing during 8-14 June, and seismic tremor persisted. Daily elevated surface temperatures identified in satellite images were consistent with the continuing effusion of short (500 m or less) lava flows. Diffuse, low-level ash emissions were visible in webcam images on 13 June. 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.

Popocatepetl, Mexico

19.023°N, 98.622°W  | Summit elev. 5393 m

CENAPRED reported that the eruption at Popocatépetl continued during 7-14 June. Each day there were 9-36 steam-and-gas emissions that rose from the crater and drifted in multiple directions. 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.

Ruapehu, North Island (New Zealand)

39.28°S, 175.57°E  | Summit elev. 2797 m

On 14 June GeoNet reported that unrest at Ruapehu continued to decline. During the previous week volcanic tremor levels were weak, but remained above background levels recorded since 2013. Lake water temperatures had dropped to 23 degrees Celsius, which corresponded to the long-term average heat flow. Relatively high sulfur dioxide and carbon dioxide measurements were recorded in mid-May, but weather conditions prevented gas measurement flights after that time. The level of unrest was at moderate levels, though the volcanic processes that caused the unrest were unknown; the Volcanic Alert Level remained at 2 (on a scale from 0-5) and the Aviation Color Code remained at Yellow.

Geological summary: Ruapehu, one of New Zealand’s most active volcanoes, is a complex stratovolcano constructed during at least four cone-building episodes dating back to about 200,000 years ago. The dominantly andesitic 110 km3 volcanic massif is elongated in a NNE-SSW direction and surrounded by another 100 km3 ring plain of volcaniclastic debris, including the NW-flank Murimoto debris-avalanche deposit. A series of subplinian eruptions took place between about 22,600 and 10,000 years ago, but pyroclastic flows have been infrequent. The broad summait area and flank contain at least six vents active during the Holocene. Frequent mild-to-moderate explosive eruptions have been recorded from the Te Wai a-Moe (Crater Lake) vent, and tephra characteristics suggest that the crater lake may have formed as recently as 3,000 years ago. Lahars resulting from phreatic eruptions at the summit crater lake are a hazard to a ski area on the upper flanks and lower river valleys.

Semeru, Eastern Java

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

PVMBG reported that the eruption at Semeru continued during 8-14 June. VONAs were issued for a few eruptive events (recorded at 0547 on 10 June, 0546 on 11 June, 0521 on 13 June, and at 0546 on 14 June) that produced ash plumes that rose 200-500 m above the summit and drifted in multiple directions. 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 away from Kobokan drainages within 17 km of the summit, and along with other drainages originating on Semeru, including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

Geological summary: Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.

Semisopochnoi, Aleutian Islands (USA)

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

AVO reported that low-level eruptive activity at Semisopochnoi’s North Cerberus cone continued during 7-14 June. Seismicity remained elevated with intermittent tremor and occasional explosions. Minor ash emissions rising to low altitudes (less than 1.5 km (5,000 ft) a.s.l.) were visible in webcam images on most days; weather clouds sometimes prevented satellite and webcam views. 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 4-9 June and explosions, hot avalanches, and lava-dome extrusion continued. A daily thermal anomaly was identified in satellite images. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Geological summary: The 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 eruption at Suwanosejima’s Ontake Crater continued during 6-13 June. Crater incandescence was visible at night. One explosion was recorded during 6-10 June, producing a plume that rose 2 km above the crater rim and ejecting material 300 m away from the vent. During 10-13 June eruption plumes rose as high as 1.5 km above the crater rim and material was ejected as far as 300 m from the vent. The Alert Level remained at 3 and the public was warned to stay 2 km away from the crater.

Geological summary: The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan’s most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Reference:

Smithsonian / US Geological Survey Weekly Volcanic Activity Report – June 8 – 14, 2022 – Managing Editor: Sally Kuhn Sennert

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