The Weekly Volcanic Activity Report: June 12 - 17, 2020

The Weekly Volcanic Activity Report: June 12 - 17, 2020

New activity/unrest was reported for 4 volcanoes from June 12 to 17, 2020. During the same period, ongoing activity was reported for 15 volcanoes.

New activity/unrest: Cleveland, Chuginadak Island (USA) | Karymsky, Eastern Kamchatka (Russia) | Makushin, Fox Islands (USA) | Sangay, Ecuador.

Ongoing activity: Aira, Kyushu (Japan) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Fuego, Guatemala | Ibu, Halmahera (Indonesia) | Klyuchevskoy, Central Kamchatka (Russia) | Nevados de Chillan, Chile | Nishinoshima, Japan | Popocatepetl, Mexico | Reykjanes, Iceland | Sangeang Api, Indonesia | Semeru, Eastern Java (Indonesia) | Sheveluch, Central Kamchatka (Russia) | Suwanosejima, Ryukyu Islands (Japan) | Whakaari/White Island, North Island (New Zealand).

New activity/unrest

Cleveland, Chuginadak Island (USA)

52.825°N, 169.944°W, Summit elev. 1730 m

AVO reported that unrest at Cleveland likely continued during 10-16 June, though no activity was identified in cloudy satellite images nor detected by regional geophysical networks. AVO noted that local seismic, infrasound, and web camera data are unavailable due to an equipment failure, Cleveland continued to be monitored with regional seismic and infrasound stations on nearby islands, along with lightning and satellite data capabilities. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Geological summary: The beautifully symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited Chuginadak Island. It lies SE across Carlisle Pass strait from Carlisle volcano and NE across Chuginadak Pass strait from Herbert volcano. Joined to the rest of Chuginadak Island by a low isthmus, Cleveland is the highest of the Islands of the Four Mountains group and is one of the most active of the Aleutian Islands. The native name, Chuginadak, refers to the Aleut goddess of fire, who was thought to reside on the volcano. Numerous large lava flows descend the steep-sided flanks. It is possible that some 18th-to-19th century eruptions attributed to Carlisle should be ascribed to Cleveland (Miller et al., 1998). In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.

Karymsky, Eastern Kamchatka (Russia)

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

KVERT reported that a weak thermal anomaly over Karymsky was identified in satellite images during 10-11 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.

Makushin, Fox Islands (USA)

53.891°N, 166.923°W, Summit elev. 1800 m

AVO reported that over a period of several hours on 15 June there were two earthquakes in the vicinity of Makushin that were greater than M 4 and one greater than M 3. The events were located about 11 km SE of the summit at a depth of about 8 km, and felt in Unalaska (14 km E). Numerous smaller earthquakes were recorded, though not felt by Unalaska residents. AVO noted that the earthquakes represented a departure from background levels and were possibly indicative of volcanic unrest; the Aviation Color Code and Volcano Alert Level were respectively raised to Yellow and Advisory. The report noted that aftershocks were continuing.

Geological summary: The ice-covered, 1800-m-high Makushin volcano on northern Unalaska Island west of the town of Dutch Harbor is capped by a 2.5-km-wide caldera. The broad, domical structure of Makushin contrasts with the steep-sided profiles of most other Aleutian stratovolcanoes. Much of the volcano was formed during the Pleistocene, but the caldera (which formed about 8000 years ago), Sugarloaf cone on the ENE flank, and a cluster of about a dozen explosion pits and cinder cones at Point Kadin on the WNW flank, are of Holocene age. A broad band of NE-SW-trending satellitic vents cuts across the volcano. The composite Pakushin cone, with multiple summit craters, lies 8 km to the SW of Makushin. Frequent explosive eruptions have occurred during the past 4000 years, sometimes accompanied by pyroclastic flows and surges. Geothermal areas are found in the summit caldera of Makushin and on the SE and eastern flanks of the volcano. They represent the largest and most investigated high-temperature geothermal resources in Alaska. Small-to-moderate explosive eruptions have been recorded at Makushin since 1786.

Sangay, Ecuador

2.005°S, 78.341°W, Summit elev. 5286 m

IG reported that for the past year, activity at Sangay is centered at two summit vents: the Central Crater which produced ash-and-gas emissions and the Ñuñurcu dome (located 190 m SSE of Central Crater) which effused lava. Lava, pyroclastic flows, and collapsed material were channeled down the Volcán River drainage on the SE flank. Activity at Sangay intensified during 8-9 June with lava-flow collapses, pyroclastic flows on the SE flank that reached the Upano River, and significant ash emissions that drifted W. No variation in seismic data was noted prior to a period of increased activity. A comparison of webcam images from 2 September 2019 and 10 June 2020 showed that the drainage had widened, deepened, and lengthened.

In recent weeks ash plumes had risen as high as 2.9 km above the crater rim and had been carried farther by strong winds. Ashfall was reported in the provinces of Chimborazo, Bolívar, Guayas, Santa Elena, Los Ríos, and Morona Santiago. Activity slightly increased during 11-12 June, characterized by ash-and-gas plumes rising higher (1.5-2.8 km above the crater rim) and drifting farther (over 600 km W and SW), and an increased number of thermal anomalies on the SE flank from intensified lava effusion. A pulse of increased seismic activity was also detected. Ashfall was additionally reported in the provinces of Tungurahua and Cotopaxi.

Geological summary: The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador's volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex.

Ongoing activity

Aira, Kyushu (Japan)

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

JMA reported that there were four explosive events and one eruptive event at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) during 8-12 June. An explosion at 1119 on 10 June produced a plume that rose 3.2 km above the crater rim and ejected large rocks 1.3-1.7 km away from the crater. Sulfur dioxide emissions remained high. No observable activity was recorded during 13-15 June, though inclement weather obscured views. The Alert Level remained at 3 (on a 5-level scale).

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.

Dukono, Halmahera (Indonesia)

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

Based on satellite and wind model data, and information from PVMBG the Darwin VAAC reported that during 10-15 June ash plumes from Dukono rose to 1.8 km (6,000 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.

Ebeko, Paramushir Island (Russia)

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

Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 8-11 June that sent ash plumes up to 2.6 km (8,500 ft) a.s.l. Ash plumes drifted E and N, and as far as 85 km N and NW on 11 June. A thermal anomaly over the volcano was identified in satellite images on 11 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.

Fuego, Guatemala

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

INSIVUMEH reported that there were 4-13 explosions per hour recorded at Fuego during 10-16 June, generating ash plumes as high as 1.1 km above the crater rim that generally drifted 10-15 km NW, W, SW, and S. Ashfall was reported in several areas downwind including Santa Sofía (12 km SW), Morelia (9 km SW), Panimaché I and II (8 km SW), Finca Palo Verde, San Pedro Yepocapa (8 km NW), Sangre de Cristo (8 km WSW), and El Porvenir (8 km ENE). Shock waves from explosions sometimes rattled houses in the vicinity of the volcano. Incandescent material was ejected 100-300 m high and caused avalanches of blocks in the Ceniza, Seca (W), Trinidad (S), Taniluyá (SW), Santa Teresa (W), Las Lajas, and Honda drainages.

A new lava flow traveled 250 m down the Seca drainage on the NW flank in the early hours of 12 June. The lava effusion was accompanied by almost constant summit crater incandescence and gas emissions. Incandescent material was ejected 100 m above the summit. Avalanches of material descended the flanks and reached vegetated areas. Ash plumes rose over 1 km and shock waves from explosions were felt. The lava flow had lengthened to 300 m by 13 June, but was an estimated 250 m long on 14 June.

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.

Ibu, Halmahera (Indonesia)

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

The Darwin VAAC reported that on 15 June ash plumes from Ibu rose to 1.8 km (6,000 ft) a.s.l. and drifted NW and W based on satellite images and weather models. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater, and 3.5 km away on the N side.

Geological summary: The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, contained several small crater lakes through much of historical time. The outer crater, 1.2 km wide, is breached on the north side, creating a steep-walled valley. A large parasitic cone is located ENE of the summit. A smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. Only a few eruptions have been recorded in historical time, the first a small explosive eruption from the summit crater in 1911. An eruption producing a lava dome that eventually covered much of the floor of the inner summit crater began in December 1998.

Klyuchevskoy, Central Kamchatka (Russia)

56.056°N, 160.642°E, Summit elev. 4754 m

KVERT reported that Strombolian activity at Klyuchevskoy was visible during 5-12 June along with a bright thermal anomaly identified in satellite images. A lava flow continued to advance down the Apakhonchich drainage on the SE flank. Gas-and-steam plumes with some ash drifted 40 km W and E on during 6-7, 9, and 11 June. The Aviation Color Code remained at Orange.

Geological summary: Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Nevados de Chillan, Chile

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

SERNAGEOMIN reported that a body of lava in Nevados de Chillán’s Nicanor Crater was visible in 11 June satellite images. The structure was oriented in the NNW direction and was about 100 m long and 60 m wide. Adjacent to the lava body was a smaller structure, oriented N. The sulfur dioxide emission rate was 300 tons/day on 14 June, which was an average rate. A thermal anomaly was visible on 10 and 14 June, and at night incandescent material was sometimes ejected from the crater. The Alert Level remained at Yellow, the second lowest level on a four-color scale, and residents were reminded not to approach the crater within 3 km. ONEMI stated that the Alert Level Yellow (the middle level on a three-color scale) remained in place for the communities of Pinto and Coihueco, and 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.

Nishinoshima, Japan

27.247°N, 140.874°E, Summit elev. 25 m

The Tokyo VAAC reported that ash plumes from Nishinoshima rose to 2.1-2.7 km (7,000-9,000 ft) a.s.l. and drifted NE and E. During an overflight on 15 June the Japan Coast Guard noted continuous activity from the central vent, including a gray-brown to black-brown ash plume rising as high as 2 km. Ejected material landed near the cone’s base. Lava from the NE side of the central vent flowed E. Steam plumes rose along the E coast where lava entered the sea, causing discolored brownish water offshore. The marine exclusion zone was defined as a radius of about 2.6 km from the island.

Geological summary: The small island of Nishinoshima was enlarged when several new islands coalesced during an eruption in 1973-74. Another eruption that began offshore in 2013 completely covered the previous exposed surface and enlarged the island again. Water discoloration has been observed on several occasions since. The island is the summit of a massive submarine volcano that has prominent satellitic peaks to the S, W, and NE. The summit of the southern cone rises to within 214 m of the sea surface 9 km SSE.

Popocatepetl, Mexico

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

CENAPRED reported that each day during 10-16 June there were 145-302 steam-and-gas emissions from Popocatépetl, some of which contained minor amounts of ash. The plumes did not rise more than 1 km above the crater rim. An overflight was conducted on 13 June by the National Guard, Instituto de Geofísica de la Universidad Nacional Autónoma de México (UNAM), and CENAPRED scientists. They noted that the inner crater was 350-380 m in diameter and 100-150 m deep; the crater floor was covered in tephra and the remains of a lava dome which had possibly been seen in May. At 1612 that same day a minor explosion was recorded, though an ash plume was not observed due to weather clouds. Incandescent material was ejected a short distance onto the flanks. Seven minor explosions were recorded on 15 June and again on 16 June. 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.

Reykjanes, Iceland

63.85°N, 22.566°W, Summit elev. 140 m

IMO reported that a third injection of magma since the beginning of the year was occurring beneath the Reykjanes peninsula. Data suggested that the current inflationary period began in mid-May, though earthquake activity did not increase until around 30 May. During 30 May-15 June the seismic network recorded more than 2,000 events, with the largest, an M 3.4, recorded on 13 June. The intrusion was located about 1 km W of Thorbjorn at a depth of 3-4 km, and had an estimated volume of about 1.2 million cubic meters. This third intrusion was similar to the previous two intrusions, characterized as a sill that was a few hundred meters wide and about 6 km long. In total about 12 cm of uplift has been recorded since January. The Svartsengi geothermal plant noted no chemical changes in the geothermal system, though measurements showed increased fluid flow in the rocks within the system, along with the opening of old cracks and the formation of new ones.

Geological summary: The Reykjanes volcanic system at the SW tip of the Reykjanes Peninsula, where the Mid-Atlantic Ridge rises above sea level, comprises a broad area of postglacial basaltic crater rows and small shield volcanoes. The submarine Reykjaneshryggur volcanic system is contiguous with and is considered part of the Reykjanes volcanic system, which is the westernmost of a series of four closely-spaced en-echelon fissure systems that extend diagonally across the Reykjanes Peninsula. Most of the subaerial part of the system (also known as the Reykjanes/Svartsengi volcanic system) is covered by Holocene lavas. Subaerial eruptions have occurred in historical time during the 13th century at several locations on the NE-SW-trending fissure system, and numerous submarine eruptions dating back to the 12th century have been observed during historical time, some of which have formed ephemeral islands. Basaltic rocks of probable Holocene age have been recovered during dredging operations, and tephra deposits from earlier Holocene eruptions are preserved on the nearby Reykjanes Peninsula.

Sangeang Api, Indonesia

8.2°S, 119.07°E, Summit elev. 1912 m

The Darwin VAAC reported that on 10 June an ash plume from Sangeang Api rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted NE. The Alert Level remained at 2 (on a scale of 1-4).

Geological summary: Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, Doro Api and Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century.

Semeru, Eastern Java (Indonesia)

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

PVMBG and the Darwin VAAC reported that on most days during 10-16 June ash plumes from Semeru rose at most 300 m above the summit and drifted N, SE, S, and SW. The Alert Level remained at 2 (on a scale of 1-4), and the public was reminded to stay outside of the general 1-km radius from the summit and 4 km on the SSE flank.

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 5-12 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.

Suwanosejima, Ryukyu Islands (Japan)

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

JMA reported that nighttime incandescence at Suwanosejima’s Ontake Crater was occasionally visible during 5-12 June. An eruptive event on 5 June produced gray-white plume rose as high as 1 km above the crater rim. The Alert Level remained at 2 (on a 5-level scale).

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 of the volcano 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

On 16 June GeoNet reported that during the previous few months activity levels at Whakaari/White Island had gradually progressed on a downward trend based on the volcano monitoring team’s collective interpretation of all the monitoring data. Temperatures at the gas vents remained high (over 450 degrees Celsius) though a slow decline in heat input from depth has been recorded. Although magma remained at a shallow depth, an estimated 1 km below the surface, gas discharge and ground deformation were not increasing. Additionally, seismic activity, specifically the level of volcanic tremor, had been low since February-March. The Volcanic Alert Level was lowered to 1 and the Aviation Color Code remained at Yellow.

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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