Active volcanoes in the world: February 17 - 23, 2016

Active volcanoes in the world: February 17 - 23, 2016

New activity/unrest was observed at 3 volcanoes from February 17 - 23, 2016. During the same period, ongoing activity was reported for 15 volcanoes. 

New activity/unrest: Bulusan, Luzon (Philippines)  | Telica, Nicaragua  | Zhupanovsky, Eastern Kamchatka (Russia).

Ongoing activity: Aira, Kyushu (Japan)  | Chirpoi, Kuril Islands (Russia)  | Colima, Mexico  | Copahue, Central Chile-Argentina border  | Dukono, Halmahera (Indonesia)  | Etna, Sicily (Italy)  | Karangetang, Siau Island (Indonesia)  | Karymsky, Eastern Kamchatka (Russia)  | Kilauea, Hawaiian Islands (USA)  | Masaya, Nicaragua  | Momotombo, Nicaragua  | Reventador, Ecuador  | Sheveluch, Central Kamchatka (Russia)  | Sinabung, Indonesia  | Tengger Caldera, Eastern Java (Indonesia).

New activity/unrest

Bulusan, Luzon (Philippines)
12.77°N, 124.05°E, Summit elev. 1565 m

PHIVOLCS reported that at 1701 on 22 February explosions at Bulusan generated a steam-and-ash plume that rose 500 m above the WNW fissure vent. The event was accompanied by a high-frequency earthquake followed by low-frequency earthquakes that lasted 4 minutes and 21 seconds. Rumbling sounds were heard in Puting Sapa, Juban, and Bolos, Irosin, and minor amounts of ash fell in barangays Puting Sapa, Sagkayon, and Caladgao in Juban, and barangay Bolos in Irosin. The report noted that no volcanic earthquakes were recorded prior to the eruption, though increased seismicity had been detected during 20-21 February. The Alert Level remained at 1, indicating abnormal conditions and a 4-km radius Permanent Danger Zone (PDZ).

Geologic 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. Bulusan 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 Bulusan 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 of 1565-m-high Bulusan volcano 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 at Bulusan since the mid-19th century.

Telica, Nicaragua
12.602°N, 86.845°W, Summit elev. 1061 m

INETER reported that high micro-seismicity at Telica was associated with gas explosions during 16-17 February. On 18 February SINAPRED stated that a small amount of lava was visible in a vent.

Geologic summary: Telica, one of Nicaragua's most active volcanoes, has erupted frequently since the beginning of the Spanish era. This volcano group consists of several interlocking cones and vents with a general NW alignment. Sixteenth-century eruptions were reported at symmetrical Santa Clara volcano at the SW end of the group. However, its eroded and breached crater has been covered by forests throughout historical time, and these eruptions may have originated from Telica, whose upper slopes in contrast are unvegetated. The steep-sided cone of 1061-m-high Telica is truncated by a 700-m-wide double crater; the southern crater, the source of recent eruptions, is 120 m deep. El Liston, immediately SE of Telica, has several nested craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, SE of Telica, form a prominent geothermal area frequented by tourists, and geothermal exploration has occurred nearby.

Zhupanovsky, Eastern Kamchatka (Russia)
53.589°N, 159.15°E, Summit elev. 2899 m

KVERT reported that moderate activity at Zhupanovsky continued during 12-19 February. On 12 February explosions generated ash plumes that rose to an altitude of 10 km (32,800 ft) a.s.l. During 12-13 February satellite images detected a thermal anomaly and ash plumes that drifted 600 km E and NE. The Aviation Color Code remained at Orange.

Geologic summary: The Zhupanovsky volcanic massif consists of four overlapping stratovolcanoes along a WNW-trending ridge. The elongated volcanic complex was constructed within a Pliocene-early Pleistocene caldera whose rim is exposed only on the eastern side. Three of the stratovolcanoes were built during the Pleistocene, the fourth is Holocene in age and was the source of all of Zhupanovsky's historical eruptions. An early Holocene stage of frequent moderate and weak eruptions from 7000 to 5000 years before present (BP) was succeeded by a period of infrequent larger eruptions that produced pyroclastic flows. The last major eruption took place about 800-900 years BP. Historical eruptions have consisted of relatively minor explosions from the third cone.

Ongoing activity

Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m

During 15-22 February JMA reported that six explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. A small-scale eruption occurred from Minamidake summit crater on 20 February. The Alert Level remained at 3 (on a 5-level scale).

Geologic 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.

Chirpoi, Kuril Islands (Russia)
46.525°N, 150.875°E, Summit elev. 742 m

SVERT reported that satellite images detected a thermal anomaly over Snow, a volcano of Chirpoi, during 16-19 February. The Aviation Color Code remained at Yellow.

Geologic summary: Chirpoi, a small island lying between the larger islands of Simushir and Urup, contains a half dozen volcanic edifices constructed within an 8-9 km wide, partially submerged caldera. The southern rim of the caldera is exposed on nearby Brat Chirpoev Island. The symmetrical Cherny volcano, which forms the 691 m high point of the island, erupted twice during the 18th and 19th centuries. The youngest volcano, Snow, originated between 1770 and 1810. It is composed almost entirely of lava flows, many of which have reached the sea on the southern coast. No historical eruptions are known from 742-m-high Brat Chirpoev, but its youthful morphology suggests recent strombolian activity.

Colima, Mexico
19.514°N, 103.62°W, Summit elev. 3850 m

Based on satellite and webcam images, and wind data, the Washington VAAC reported that during 18-19 February gas-and-ash plumes from Colima rose to altitudes of 4.6-5.5 km (15,000-18,000 ft) a.s.l. and drifted N, S, and SSW.

Geologic summary: The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4320 m high point of the complex) on the north and the 3850-m-high historically active Volcán de Colima at the south. A group of cinder cones of late-Pleistocene age is located on the floor of the Colima graben west and east of the Colima complex. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the south, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.

Copahue, Central Chile-Argentina border
37.856°S, 71.183°W, Summit elev. 2953 m

Based on satellite and webcam views, the Buenos Aires VAAC reported that on 17 and 20 February steam plumes containing minor amounts of ash rose from Copahue and drifted SE at an altitude of 3.3 km (11,000 ft) a.s.l. Only gas emissions were visible on 19 February.

Geologic summary: Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded at Copahue since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.

Dukono, Halmahera (Indonesia)
1.693°N, 127.894°E, Summit elev. 1229 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 17-23 February ash plumes from Dukono rose to altitude of 2.7-3 km (8,000-10,000 ft) a.s.l. and drifted 55-225 km in multiple directions.

Geologic 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.

Etna, Sicily (Italy)
37.734°N, 15.004°E, Summit elev. 3330 m

INGV reported that during January eruptive activity at Etna was at low levels. During the last week of January and on 6 February ash emissions rose from a vent located high on the E flank of the New Southeast Crater (NSEC) cone. At 0422 on 23 February an explosion at Northeast Crater (NEC) ejected incandescent tephra several tens of meters above the crater rim, and produced a dark ash plume that drifted NE. A camera recorded lightning flashes in the plume. Weak ash emission rose from the crater during the rest of the morning.

Geologic 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 at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater (the latter formed in 1978). 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.

Karangetang, Siau Island (Indonesia)
2.78°N, 125.4°E, Summit elev. 1784 m

Based on observations conducted at the Karangetang Volcano Observation Post in the village of Salili, PVMBG reported that during 10-17 February the lava dome was incandescent at night. Variable amounts of white and blue emissions rose as high as 100 m above Main Crater. RSAM values doubled in January and continued to rise in February due to an increased number of shallow volcanic earthquakes. The Alert Level remained at 3 (on a scale of 1-4); visitors and residents were warned not to approach Karangetang within a 4-km radius.

Geologic summary: Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, north of Sulawesi. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.

Karymsky, Eastern Kamchatka (Russia)
54.049°N, 159.443°E, Summit elev. 1513 m

KVERT reported that moderate explosive activity at Karymsky continued during 12-19 February. Satellite images detected a daily thermal anomaly, and ash plumes from explosions that drifted about 125 km E. The Aviation Color Code remained at Orange.

Geologic 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 seismicity beneath Kilauea's summit, upper East Rift Zone, and Southwest Rift Zone was at background levels during 17-23 February. The lava lake continued to circulate and spatter in the Overlook vent. A moderate-size collapse of part of the crater wall into the summit lava lake on 21 February ejected some ash onto the caldera rim. Webcams recorded multiple incandescent outgassing vents within Pu'u 'O'o Crater and high on the northeast rim. The June 27th NE-trending lava flow continued to be active within 6 km NE of Pu'u 'O'o Crater, burning some areas of forest.

Geologic summary: Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions of Kilauea are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.

Masaya, Nicaragua
11.984°N, 86.161°W, Summit elev. 635 m

On 17 February INETER reported that the lava lake on the floor of Masaya's Santiago crater remained visible. RSAM values were at high levels and gas emissions were low.

Geologic summary: Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras pyroclastic shield volcano and is a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The twin volcanoes of Nindirí and Masaya, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic plinian tephra erupted from Masaya about 6500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals cause health hazards and crop damage.

Momotombo, Nicaragua
12.422°N, 86.54°W, Summit elev. 1297 m

INETER reported that during 16-17 February two explosions at Momotombo were accompanied by tremor, and produced ash emissions and ejected incandescent material onto the flanks. The first and largest explosion (recorded at 0344) ejected incandescent tephra 800 m above the crater. RSAM values were at low-to-moderate levels. Based on webcam views and satellite images, the Washington VAAC reported that on 19 February ash emissions rose to an altitude of 3.6 km (12,000 ft) a.s.l. and drifted SW and WSW. The next day ash emissions drifted SW. On 21 February ash plumes drifted about 80 km W and 25 km E.

Geologic summary: Momotombo is a young, 1297-m-high stratovolcano that rises prominently above the NW shore of Lake Managua, forming one of Nicaragua's most familiar landmarks. Momotombo began growing about 4500 years ago at the SE end of the Marrabios Range and consists of a somma from an older edifice that is surmounted by a symmetrical younger cone with a 150 x 250 m wide summit crater. Young lava flows from Momotombo have flowed down the NW flank into the 4-km-wide Monte Galán caldera. The youthful cone of Momotombito forms a 391-m-high island offshore in Lake Managua. Momotombo has a long record of strombolian eruptions, punctuated by occasional larger explosive activity. The latest eruption, in 1905, produced a lava flow that traveled from the summit to the lower NE base. A small black plume was seen above the crater after an April 10, 1996 earthquake, but later observations noted no significant changes in the crater. A major geothermal field is located on the southern flank of the volcano.

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

During 17-23 February IG reported a high level of seismic activity including explosions, volcano-tectonic events, long-period earthquakes, harmonic and spasmodic tremor, and signals indicating emissions at Reventador; cloud cover often prevented visual observations. On 18 February a gas-and-ash plume rose 500 m above the crater and drifted NW.

Geologic 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.

Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m

KVERT reported that during 12-19 February lava-dome extrusion onto Sheveluch’s N flank was accompanied by fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Explosions on 18 February generated ash plumes that drifted NE. Satellite images detected a daily and intense thermal anomaly over the dome. The Aviation Color Code remained at Orange.

Geologic summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 cu km 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

Based on satellite images, ground reports, and information from PVMBG, the Darwin VAAC reported that during 18 and 20-23 February ash plumes from Sinabung rose to altitudes of 3-5.5 km (10,000-18,000 ft) a.s.l. and drifted as far as 55 km S, SW, W, and NW.

Geologic 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, 2460-m-high andesitic-to-dacitic volcano is at the southern end of the four overlapping summit craters. 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.

Tengger Caldera, Eastern Java (Indonesia)
7.942°S, 112.95°E, Summit elev. 2329 m

Based on satellite images, wind data, ground reports, and information from PVMBG, the Darwin VAAC reported that during 17-23 February ash plumes from Tengger Caldera's Bromo cone rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted at most 55 km NW, ESE, and SE.

Geologic summary: The 16-km-wide Tengger caldera is located at the northern end of a volcanic massif extending from Semeru volcano. The massive volcanic complex dates back to about 820,000 years ago and consists of five overlapping stratovolcanoes, each truncated by a caldera. Lava domes, pyroclastic cones, and a maar occupy the flanks of the massif. The Ngadisari caldera at the NE end of the complex formed about 150,000 years ago and is now drained through the Sapikerep valley. The most recent of the calderas is the 9 x 10 km wide Sandsea caldera at the SW end of the complex, which formed incrementally during the late Pleistocene and early Holocene. An overlapping cluster of post-caldera cones was constructed on the floor of the Sandsea caldera within the past several thousand years. The youngest of these is Bromo, one of Java's most active and most frequently visited volcanoes.

Source: GVP

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