New activity/unrest was reported for 3 volcanoes from September 16 to 22, 2020. During the same period, ongoing activity was reported for 13 volcanoes.
New activity/unrest: Erta Ale, Ethiopia | Pavlof, United States | Sangay, Ecuador.
Ongoing activity: Aira, Kyushu (Japan) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Etna, Sicily (Italy) | Fuego, Guatemala | Ibu, Halmahera (Indonesia) | Kadovar, Papua New Guinea | Nevados de Chillan, Chile | Popocatepetl, Mexico | Rincon de la Vieja, Costa Rica | Semeru, Eastern Java (Indonesia) | Sheveluch, Central Kamchatka (Russia) | Suwanosejima, Ryukyu Islands (Japan).
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 "Criteria and Disclaimers" section. Carefully reviewed, detailed reports about recent activity are published in issues of the Bulletin of the Global Volcanism Network.
Erta Ale, Ethiopia
13.6°N, 40.67°E, Summit elev. 613 m
Satellite data showed thermal anomalies in both of Erta Ale’s S and N pit craters in mid-August, though by 5 September only the N pit had anomalous temperatures.
Geological summary: Erta Ale is an isolated basaltic shield that is the most active volcano in Ethiopia. The broad, 50-km-wide edifice rises more than 600 m from below sea level in the barren Danakil depression. Erta Ale is the namesake and most prominent feature of the Erta Ale Range. The volcano contains a 0.7 x 1.6 km, elliptical summit crater housing 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 is renowned for one, or sometimes two long-term lava lakes that have been active since at least 1967, or possibly since 1906. Recent fissure eruptions have occurred on the N flank.
Pavlof, United States
55.417°N, 161.894°W, Summit elev. 2493 m
On 21 September AVO announced that the Volcano Alert Level for Pavlof was raised to Advisory and the Aviation Color Code was raised to Yellow. Seismicity had increased above background levels during the previous day and was characterized by ongoing tremor.
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.
2.005°S, 78.341°W, Summit elev. 5286 m
IG reported a high level of activity at Sangay during 15-22 September. Seismicity was characterized by high levels of explosions, harmonic tremor, long-period earthquakes, and signals indicating emissions. Weather clouds sometimes prevented visual observations of the volcano, but the Washington VAAC and IG webcams recorded daily ash plumes that rose as high as 2 km above the summit and drifted in multiple directions. Pyroclastic flows descended the SE flank almost daily.
An explosion at 0420 on 20 September was the largest such event in the recent months. Within 10 minutes several satellite images showed a large ash cloud rising 6-10 km above the summit; high-altitude parts of the cloud drifted E while lower parts drifted W. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) reported that 32 districts within the provinces of Chimborazo, Bolívar, Guayas, and Los Ríos were affected by ashfall. Authorities in the districts of Bucay and Cumandá restricted driving, the opening of businesses, and outdoor activities due to ashfall. The José Joaquín de Olmedo Airport in Guayaquil suspended its operations for seven hours to clean the runways. Ashfall was most significant in Chimborazo, particularly in the districts of Guamote, Alausí, Chunchi, Pallatanga, and Cumandá, with photos showing poor visibility and ashfall covering streets, cars, and houses. Ashfall significantly impacted agriculture fields.
Authorities inspected the confluence of the Volcán River (SE flank) and Upano River, and observed significant deposits of tephra, some of which had damned the river and created an immense lagoon. Normally the Upano was about 25 m wide in that area but because of the deposits it was more than 250 m across and had almost no water in it. After the explosion, IG noted that activity returned to levels similar to previous months with ash plumes rising 1-2 km above the volcano during 20-22 September.
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.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m
JMA reported that very small eruptive events at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) were occasionally recorded during 14-21 September. Crater incandescence was visible at night. An eruption at 0810 on 15 September generated an ash plume that rose 1 km above the crater rim. 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 17-22 September ash plumes from Dukono rose 2.1 km (7,000 ft) a.s.l. and drifted SW, W, NW, and N. 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 11 and 14-17 September that sent ash plumes up to 3 km (10,000 ft) a.s.l. and drifted SE, E, N, and NW. A thermal anomaly over the volcano was visible in satellite data on 13 and 15 September. Ash fell in Severo-Kurilsk during 14-15 September. 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 that during 14-20 September activity at Etna’s New Southeast Crater (NSEC) was characterized by Strombolian activity and ash emissions. The ejection of incandescent material onto the crater rim and the S flank was occasionally visible during phases of increased activity. Minor ash emissions sporadically rose from Voragine Crater (VOR). Strombolian activity also occurred within Northeast Crater (NEC).
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.
14.473°N, 90.88°W, Summit elev. 3763 m
INSIVUMEH reported that effusive activity at Fuego decreased as of 16 September; the lava flow that had descended the Ceniza drainage (SSW) was no longer active. There were 6-16 explosions per hour recorded during 16-22 September, generating ash plumes as high as 1.1 km above the crater rim that generally drifted 7-20 km in multiple directions. Shock waves rattled buildings within a 20-km radius. Sometimes incandescent material ejected 100-300 m high caused avalanches of blocks in the Ceniza, Seca (W), Trinidad (S), Taniluyá (SW), Las Lajas, and Honda drainages; avalanches sometimes reached vegetated areas. Ashfall was reported daily in several areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Finca Palo Verde, Santa Sofía (12 km SW), San Pedro Yepocapa (8 km NW), and Sangre de Cristo (8 km WSW). During 18-19 September lahars descended the Ceniza, Las Lajas, and Honda drainages, carrying tree branches, trunks, and blocks as large as 1.5 m in diameter. Additionally, lava flows traveled 200-350 m down the Seca and Ceniza drainages.
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
PVMBG reported that during 15-22 September white-and-gray ash plumes rose 200-800 m above Ibu’s summit and drifted in multiple directions. 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.
Kadovar, Papua New Guinea
3.608°S, 144.588°E, Summit elev. 365 m
Based on satellite data, the Darwin VAAC reported that during 21-22 September ash plumes from Kadovar rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted NW.
Geological summary: The 2-km-wide island of Kadovar is the emergent summit of a Bismarck Sea stratovolcano of Holocene age. It is part of the Schouten Islands, and lies off the coast of New Guinea, about 25 km N of the mouth of the Sepik River. Prior to an eruption that began in 2018, a lava dome formed the high point of the andesitic volcano, filling an arcuate landslide scarp open to the south; submarine debris-avalanche deposits occur in that direction. Thick lava flows with columnar jointing forms low cliffs along the coast. The youthful island lacks fringing or offshore reefs. A period of heightened thermal phenomena took place in 1976. An eruption began in January 2018 that included lava effusion from vents at the summit and at the E coast.
Nevados de Chillan, Chile
36.868°S, 71.378°W, Summit elev. 3180 m
On 22 September SERNAGEOMIN reported that lava continued to advance down Nevados de Chillán’s NNE flank. Gas emissions and occasional explosions were also recorded. 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 Alert Level Yellow (the middle level on a three-color scale) remained in place for the communities of Pinto and Coihueco, noting that as of 16 June the public should stay at least 3 km away from the crater on the SW flank and 5 km away on the NE flank.
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.
19.023°N, 98.622°W, Summit elev. 5393 m
CENAPRED reported that each day during 16-21 September there were 52-121 steam-and-gas emissions from Popocatépetl, most of which contained minor amounts of ash. Weather clouds often obscured views of the volcano. 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.
Rincon de la Vieja, Costa Rica
10.83°N, 85.324°W, Summit elev. 1916 m
OVSICORI-UNA reported that small, frequent eruptions at Rincón de la Vieja continued to be recorded, though sometimes not visually confirmed, during 16-22 September. A larger event, at 1053 on 22 September, ejected material out of the crater and into the drainages on the N flank.
Geological summary: Rincón de la Vieja, the largest volcano in NW Costa Rica, is a remote volcanic complex in the Guanacaste Range. The volcano consists of an elongated, arcuate NW-SE-trending ridge constructed within the 15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on the south side. Sometimes known as the "Colossus of Guanacaste," it has an estimated volume of 130 km3 and contains at least nine major eruptive centers. Activity has migrated to the SE, where the youngest-looking craters are located. The twin cone of Santa María volcano, the highest peak of the complex, is located at the eastern end of a smaller, 5-km-wide caldera and has a 500-m-wide crater. A Plinian eruption producing the 0.25 km3 Río Blanca tephra about 3,500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous historical eruptions possibly dating back to the 16th century, have been from the prominent active crater containing a 500-m-wide acid lake located ENE of Von Seebach crater.
Semeru, Eastern Java (Indonesia)
8.108°S, 112.922°E, Summit elev. 3657 m
According to PVMBG ground-based observers noted ash plumes from Semeru rising 500 m above the summit and drifting SE on 17 September. An ash plume rose 200 m and drifted N the next day. The Alert Level remained at 2 (on a scale of 1-4).
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 11, 13-14, and 16-17 September; weather clouds prevented views on other days during 11-18 September. 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 nighttime incandescence at Suwanosejima’s Ontake Crater during 11-18 September. An explosion at 0155 on 15 September generated an ash plume that rose 1.5 km above the crater rim and ejected large rocks as far as 400 m from the crater. 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 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.
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