The Weekly Volcanic Activity Report: June 2 - 8, 2021

The Weekly Volcanic Activity Report: June 2 - 8, 2021

New activity/unrest was reported for 2 volcanoes from June 2 to 8, 2021. During the same period, ongoing activity was reported for 18 volcanoes.

New activity/unrest: Gareloi, United States | Semisopochnoi, Aleutian Islands (USA).

Ongoing activity: Aira, Kyushu (Japan) | Ebeko, Paramushir Island (Russia) | Etna, Sicily (Italy) | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Kerinci, Indonesia | Krysuvik-Trolladyngja, Iceland | Lewotolok, Lembata Island (Indonesia) | Merapi, Central Java (Indonesia) | Nevados de Chillan, Chile | Popocatepetl, Mexico | Reventador, Ecuador | Santa Maria, Guatemala | Semeru, Eastern Java (Indonesia) | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Suwanosejima, Ryukyu Islands (Japan) | Whakaari/White Island, North Island (New Zealand).

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 23:00 UTC every Wednesday, these reports are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the GVP's "Criteria and Disclaimers" section. Carefully reviewed, detailed reports about recent activity are published in issues of the Bulletin of the Global Volcanism Network.

New activity/unrest

Gareloi, United States

51.79°N, 178.794°W, Summit elev. 1573 m

AVO reported that a minor increase in seismicity was first detected at Gareloi on 19 May. Beginning on 27 May the rate and size of small volcanic earthquakes increased and was sustained at that level. On 8 June AVO raised the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory based on seismicity rising above baseline levels. Sulfur dioxide emissions had been identified in satellite images the past week, though they were consistent with measurements recorded in previous years. No other changes were evident in satellite or webcam views.

Geological summary: The 8 x 10 km Gareloi Island, the northernmost volcano of the Delarof Group at the western end of the Andreanof Islands, consists of a stratovolcano with two summits and a prominent SE-trending fissure. The fissure was formed during an eruption in 1929 and extends from the southern summit to the sea. Steep sea cliffs that are cut into rocks of an older, eroded center are found on the SW coast, and submarine deposits of three debris avalanches produced by edifice collapse are found offshore. Young lava flows cover the older volcano from the summit to the coast along three broad axes trending NW, ENE, and S. The 1929 eruption originated from 13 craters along a 4-km-long fissure. Phreatic explosions were followed by the ejection of glassy pumice, lapilli, scoria, and older blocks, as well as by the emission of four short, steep lava flows, one of which reached the SE coast.

Semisopochnoi, Aleutian Islands (USA)

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

AVO reported that low-level unrest at Semisopochnoi continued during 2-8 June with seismicity occasionally above background levels. Steaming from Mount Cerberus was sometimes observed by field crews. Slightly elevated surface temperatures were identified in a few satellite infrared images during 4-7 June. 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.

Ongoing activity

Aira, Kyushu (Japan)

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

JMA reported that during 31 May-7 June incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly and very small eruptive events were occasionally recorded. The sulfur dioxide emission rate was 2,700 tons per day on 2 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.

Ebeko, Paramushir Island (Russia)

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

According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, an explosion on 28 May produced an ash plume that rose to 4.5 km (10,500 ft) a.s.l. and drifted NE. A thermal anomaly was identified in satellite images on 2 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Etna, Sicily (Italy)

37.748°N, 14.999°E, Summit elev. 3320 m

INGV reported a few eruptive episodes at Etna’s Southeast Crater (SEC) during 31 May-6 June, as well as minor and diffuse ash emissions at Bocca Nuova (BN) and ash emissions on 4 June at Northeast (NEC). Weak Strombolian activity at SEC began at 0850 on 2 June and produced minor and diffuse ash plumes. The activity intensified at 1000; within 30 minutes lava fountaining was observed and lasted for over two hours. Ash plumes rose 5-6 km (16,400-19,700 ft) a.s.l. and drifted E, causing ashfall in Petrulli, Santa Venerina, and in an areas N of Zafferana. Lava overflowed the S side of the crater and traveled W. Fountaining stopped at 1245. Weak Strombolian activity continued to be observed during the night hours of 3-4 June.

Activity increased at 1530 on 4 June and was characterized by discontinuous ash emissions and lava overflowing the S rim of SEC. Lava fountaining began at 1820 and an ash plume rose to 6.5 km (21,300 ft) a.s.l. Tephra fell in Aci Castello, Acitrezza, San Giovanni La Punta, Tremestieri, Catania, and Viagrande, and between Pedara, Fleri, and Siracusa. Fountaining began to decline at 1930. The lava flow continued to advance, and by 2300 had reached 2,800 m elevation. Occasional ash emissions were noted during 4-5 June, and the lava flow had ceased.

Geological summary: Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical 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 horseshoe-shaped 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.

Fuego, Guatemala

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

INSIVUMEH reported that 5-13 explosions per hour were recorded during 1-8 June at Fuego, generating ash plumes as high as 1.1 km above the crater rim. Shock waves often rattled buildings around the volcano. Ashfall was reported almost daily in several areas downwind, including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Sangre de Cristo (8 km WSW), and San Pedro Yepocapa (8 km NW). Block avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Las Lajas (SE), and Honda drainages, often reaching vegetated areas. Explosions ejected incandescent material 100-350 m above the summit on most days.

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.

Karymsky, Eastern Kamchatka (Russia)

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

KVERT reported that a thermal anomaly over Karymsky was visible in satellite images during 28-31 and 2-3 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

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

Kerinci, Indonesia

1.697°S, 101.264°E, Summit elev. 3800 m

The Darwin VAAC reported that on 6 June an ash plume from Kerinci rose to 4 km (13,000 ft) a.s.l. and drifted WNW. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 3-km exclusion zone.

Geological summary: Gunung Kerinci in central Sumatra forms Indonesia's highest volcano and is one of the most active in Sumatra. It is capped by an unvegetated young summit cone that was constructed NE of an older crater remnant. There is a deep 600-m-wide summit crater often partially filled by a small crater lake that lies on the NE crater floor, opposite the SW-rim summit. The massive 13 x 25 km wide volcano towers 2400-3300 m above surrounding plains and is elongated in a N-S direction. Frequently active, Kerinci has been the source of numerous moderate explosive eruptions since its first recorded eruption in 1838.

Krysuvik-Trolladyngja, Iceland

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

The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 2-8 June. The flow rate at the fifth vent, now the main lava source, was 12.4 cubic meters per second by 3 June, similar to the 11-13 cubic meters per second measured in May. Cycles of lava fountaining followed by no activity persisted at the fifth vent, though observers noted that the vent opening was getting smaller as the crater walls thickened. One observer described standing waves of lava 20 m high during a period of greater lava effusion. Lava advanced in the Nátthaga, Geldingadalur, and Merardalur valleys. The flows in Nátthaga continued to get closer to Highway 427 (Suðurstrandarvegur) to the S, covering an area with buried fiber optic communication cables. The leading edge of the flow ignited vegetation, causing small fires. The Aviation Color Code remained at Orange due to the lack of ash and tephra emissions, though IMO warned of the potential for lapilli and scoria fallout within a 650 m radius of the active vent. Authorities warned of increased gas emissions hazards.

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.

Lewotolok, Lembata Island (Indonesia)

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

PVMBG reported that white-and-gray plumes from Lewotolok rose as high as 500 m and drifted W and E almost daily during 1-8 June. Rumbling was heard every day. Crater incandescence was visible during 1 and 3-4 June. Incandescent material was ejected as far as 300 m in all directions during 3-4 June and as far as 1 km NW during 5-6 June. 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.

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 (Indonesia)

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

PVMBG reported that the eruption at Merapi continued during 1-8 June. As many as 16 daily incandescent avalanches were recorded, traveling as far as 2 km down the SW flank. Pyroclastic flows traveled as far as 1.6 km down the SW flank during 5-8 June. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.

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.

Nevados de Chillan, Chile

36.868°S, 71.378°W, Summit elev. 3180 m

SERNAGEOMIN reported continuing explosive and effusive activity at Nevados de Chillán’s Nicanor Crater during 16 May-2 June, and increased sulfur dioxide emissions and thermal anomalies. Explosions partly destroyed the dome, generating ash plumes that rose as high as 1.4 km above the crater rim and pyroclastic flows that traveled as far as 1.1 km down the NE flank. Satellite images indicated that the L5 lava flow did not lengthen, remaining at 966 m, though the distal part of the flow widened. The L6 lava flow advanced at a rate of 1.16 m per hour to over 890 m long. The average temperature was 101 degrees Celsius with a maximum of 264 for L5 and an average of 121 degrees Celsius with a maximum of 293 for L6. A new lobate flow emerged just to the N of L6; measurements on 2 June indicated that the temperature of the flow was similar to that of L6. Data indicated that the lava dome in Nicanor Crater did not get larger. The average sulfur dioxide emission rate was 706 (± 216) tons/day, reaching a high value of 1,101 on 27 May. The number and intensity of thermal anomalies increased, and were notable on 20, 23, 25, 28, and 30 May, likely due to the active lava flows. The Alert Level remained at Yellow, the second lowest level on a four-color scale. ONEMI stated that Alert Level Yellow (the middle level on a three-color scale) remained in place for the communities of Pinto and Coihueco, noting that the public should stay at least 2 km away from the crater.

Geological summary: The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The largest stratovolcano, dominantly andesitic, Cerro Blanco (Volcán Nevado), is located at the NW end of the group. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in elevation. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and eventually exceeded its height.

Popocatepetl, Mexico

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

CENAPRED reported that each day during 2-8 June there were 87-136 steam-and-gas emissions with minor amounts of ash from Popocatépetl and periods of low-amplitude tremor lasting from five minutes to about three hours and 40 minutes. Minor crater incandescence was visible overnight during most nights. The Alert Level remained at Yellow, Phase Two (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.

Reventador, Ecuador

0.077°S, 77.656°W, Summit elev. 3562 m

IG reported that a high level of activity continued to be recorded at Reventador during 1-8 June; adverse weather conditions sometimes prevented visual confirmation. Seismicity was characterized by 3-23 daily explosions, volcano-tectonic and harmonic tremor events, long-period earthquakes, and signals indicating emissions. Gas, steam, and ash plumes, often observed multiple times a day with the webcam or reported by the Washington VAAC, rose higher than 1 km above the summit crater and drifted mainly W, NW, and NE. Crater incandescence and incandescent blocks rolling as far as 500 m down the S flank were occasionally observed at night. Lava flows on the N, NE, SE, and S flanks were active. The report also noted that a bulging area on the N flank first detected on 13 May had persisted.

Geological summary: Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

Santa Maria, Guatemala

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

INSIVUMEH reported that during 1-8 June daily explosions at Santa María’s Santiaguito lava-dome complex generated ash plumes that rose as high as 1.1 km above the summit and drifted SE, SW, and W. Collapses of blocky lava from Caliente dome sent avalanches down the S, SW, and W flanks, sometimes reaching the base, and caused minor ashfall mostly on the volcano’s flank. Ashfall was also reported in San Marcos (8 km SW) and Loma Linda Palajunoj (6 km WSW) during 4-5 June.

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 (Indonesia)

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

PVMBG reported that Semeru continued to erupt during 1-8 June. Inclement weather often prevented visual observations, through gray-and-white plumes were visible on 3 and 6 June rising 200-500 m above the summit and drifting S and SW. The Darwin VAAC reported that during 2, 5-6, and 8 June ash plumes rose as high as 4.3 km (14,000 ft) a.s.l., or about 600 m above the summit, and drifted SE, SW, W, and NW. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 5 km in the SSE sector.

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 a thermal anomaly over Sheveluch was identified in satellite images during 28 May-4 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Sinabung, Indonesia

3.17°N, 98.392°E, Summit elev. 2460 m

PVMBG reported that the eruption at Sinabung continued during 2-8 June. An eruptive event was recorded at 2004 on 3 June but not visually confirmed due to inclement weather. Another event, at 2335 on 6 June, produced ash plumes and pyroclastic flows, though weather again inhibited visual observations. The Darwin VAAC reported that an ash plume rose to 9.1 km (30,000 ft) a.s.l. and drifted W and SW. Ash continued to be identified in satellite images; the next day ash clouds drifted W and WSW at 9.1 km, W at 7.3 km (24,000 ft) a.s.l., WNW at 6.1 km (20,000 ft) a.s.l., and N at 4.3 km (14,000 ft) a.s.l. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Geological summary: Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. The youngest deposit is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at 740-880 CE. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.

Suwanosejima, Ryukyu Islands (Japan)

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

JMA reported that 33 explosions at Suwanosejima's Ontake Crater produced eruption plumes that rose as high as 2.6 km above the crater rim during 28 May-4 June. Large volcanic bombs were ejected 500 m from the crater. Ashfall was reported in Toshima village (4 km SSW). Crater incandescence was visible nightly. 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.

Whakaari/White Island, North Island (New Zealand)

37.52°S, 177.18°E, Summit elev. 294 m

According to GeoNet water filled in the vents of Whakaari/White Island’s 2019 Primary Crater based on 18 May webcam views. During an observation overflight on 27 May scientists confirmed the new lakelet and noted that several active steam and gas vents were under water. Thermal infrared measurements indicated that temperatures had cooled significantly. Gas emissions had not notably changed over the previous few months. A persistent gas-and-steam plume likely produced acid rain on the island. A period of low-energy volcanic tremor began at around 0400 on 1 June and lasted for two hours. Activity rapidly returned to low levels afterwards. Overall, seismicity was at background levels. The Volcanic Alert Level remained at 1 and the Aviation Color Code remained at Green.

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

Source: GVP

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