New activity/unrest was observed at 4 volcanoes from February 10 – 16, 2016. During the same period, ongoing activity was reported for 18 volcanoes.
New activity/unrest: Aira, Kyushu (Japan) | Semeru, Eastern Java (Indonesia) | Soputan, Sulawesi (Indonesia) | Zhupanovsky, Eastern Kamchatka (Russia).
Ongoing activity: Barren Island, Andaman Islands (India) | Chirpoi, Kuril Islands (Russia) | Colima, Mexico | Copahue, Central Chile-Argentina border | Dukono, Halmahera (Indonesia) | Fuego, Guatemala | Karangetang, Siau Island (Indonesia) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaiian Islands (USA) | Masaya, Nicaragua | Momotombo, Nicaragua | Nevado del Ruiz, Colombia | Popocatepetl, Mexico | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Telica, Nicaragua | Tengger Caldera, Eastern Java (Indonesia).
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m
During 8-15 February JMA reported that 11 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. Based on JMA reports and satellite data, the Tokyo VAAC reported that during 10-12 February ash plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted N, NW, W, S, and SE. On 14 February a pilot observed an ash plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted S. 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.
Semeru, Eastern Java (Indonesia)
8.108°S, 112.92°E, Summit elev. 3676 m
Based on analysis of satellite imagery and information from PVMBG, the Darwin VAAC reported that during 13-14 February ash plumes from Semeru rose to altitudes of 6.7-7.9 km (22,000-26,000 ft) a.s.l. and drifted NE. According to a news article, a lava-dome collapse on 13 February generated pyroclastic flows that traveled 4-5 km down the S and SE flanks; the nearest village in that direction is 9 km away.
Geologic 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 abruptly to 3676 m 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. Semeru has been in almost continuous eruption since 1967.
Soputan, Sulawesi (Indonesia)
1.112°N, 124.737°E, Summit elev. 1785 m
PVMBG reported that during 9-15 February diffuse white plumes from Soputan rose as high as 200 m above the crater. Seismicity was dominated by signals indicating avalanches and emissions, though volcanic and low-frequency earthquakes were also detected. The Alert Level remained at 3 (on a scale of 1-4); residents and tourists were advised not to approach the craters within a radius of 6.5 km.
Geologic summary: The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano rises to 1784 m and is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.
Zhupanovsky, Eastern Kamchatka (Russia)
53.589°N, 159.15°E, Summit elev. 2899 m
KVERT reported that moderate steam-and-gas activity at Zhupanovsky continued during 5-12 February. Explosions on 5, 7, and 9 February generated ash plumes detected in satellite images that drifted over 545 km E and N. A thermal anomaly was detected during 5 and 9-11 February. An explosion at 0929 on 13 February was recorded by a video camera and generated an ash plume that rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted E. A larger explosion visually observed a minute later generated an ash plume that rose to an altitude of 10 km (32,800 ft) a.s.l. and drifted 50 km SE. The Aviation Color Code was raised to Red. In a report issued at 1134, KVERT noted that only moderate amounts of gas and steam rose from the volcano; the Aviation Color Code was lowered to Orange. Ash from the earlier explosions drifted E over Kronotsky Bay and NW. A few hours later an ash plume was detected in satellite images rising 1 km above the volcano and drifting 288 km E.
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.
Barren Island, Andaman Islands (India)
12.278°N, 93.858°E, Summit elev. 354 m
Based on analysis of satellite imagery and wind data, the Darwin VAAC reported that during 14-15 February ash plumes from Barren Island rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted over 45 km W.
Geologic summary: Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit of a volcano that rises from a depth of about 2250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with walls 250-350 m high. The caldera, which is open to the sea on the west, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic-flow and -surge deposits. Historical eruptions have changed the morphology of the pyroclastic cone in the center of the caldera, and lava flows that fill much of the caldera floor have reached the sea along the western coast.
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, on 8 and 11 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.
19.514°N, 103.62°W, Summit elev. 3850 m
Based on satellite and webcam images, and notices from the Mexico City MWO, the Washington VAAC reported that during 14-15 February ash plumes from Colima rose to an altitude of 5.8 km (19,000 ft) a.s.l. and drifted E and SE.
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 during 10-16 February Copahue generated almost continuous steam plumes containing minor amounts of ash that rose to altitudes of 3-3.6 km (10,000-12,000 ft) a.s.l. and drifted NE, E, SE, S, and SW.
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 10-16 February ash plumes from Dukono rose to altitude of 2.4-3 km (7,000-10,000 ft) a.s.l. and drifted 35-160 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.
14.473°N, 90.88°W, Summit elev. 3763 m
In a special report, INSIVUMEH noted that the third episode of effusive activity at Fuego for 2016 had ended at 1830 on 10 February. Afterward some minor explosions generated ash plumes that rose 450 m above the crater and drifted 10 km NNE. Lava flows had traveled 3 km down the Las Lajas drainage (SE) and in the Trinidad drainage (S). During 11-16 February explosions generated ash plumes that rose 350-550 m and drifted almost 11 km W, SW, S, and SE.
Geologic summary: Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. 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 Acatenango. In contrast to 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.
Karangetang, Siau Island (Indonesia)
2.78°N, 125.4°E, Summit elev. 1784 m
Based on observations from the Karangetang Volcano Observation Post in the village of Salili, PVMBG reported that during 3-10 February the lava dome was incandescent at night. Variable amounts of white and blue emissions rose as high as 100 m above Main Crater, and roaring was occasionally heard. RSAM values doubled in January and continued to rise in February due to an increase in the 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 5-12 February. Satellite images detected a daily thermal anomaly, and ash plumes that drifted about 170 km E and SE. 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 10-16 February. The lava lake continued to circulate and spatter in the Overlook vent. 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.
11.984°N, 86.161°W, Summit elev. 635 m
During 10-11 February sulfur dioxide emissions at Masaya rose to high levels (1,500 tons per day), and RSAM values were at moderately-high levels due to higher levels of volcanic tremor. This activity coincided with an increase in the size of the lava lake. Gas emissions were at moderate and low levels on 12 and 16 February, respectively.
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.
12.422°N, 86.54°W, Summit elev. 1297 m
INETER reported moderate levels of gas emissions at Momotombo on 10 February; volcanic tremor and gas emissions increased to moderate-to-high levels the next day. An explosion on 12 February produced small ash emissions and ejected incandescent material onto the N and SE flanks. An explosion at 1305 on 15 February generated an ash plume that rose 2 km above the crater and ejected incandescent tephra onto the N and NE flanks.
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.
Nevado del Ruiz, Colombia
4.892°N, 75.324°W, Summit elev. 5279 m
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 9-15 February seismicity at Nevado del Ruiz was characterized by long-period earthquakes and pulses of volcanic tremor associated with gas-and-ash emissions. Earthquakes occurred at depths between 1 and 7.6 km. The largest event was recorded at 0857 on 10 February; it was a local M 1.1, N of Arenas Crater at a depth of 5.7 km. Significant amounts of water vapor and gas rose from the crater during the week. A gas, steam, and ash plume rose 1.5 km and drifted NW on 13 February. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").
Geologic summary: Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers >200 sq km. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America's deadliest eruption.
19.023°N, 98.622°W, Summit elev. 5426 m
CENAPRED reported that during 10-16 February the seismic network at Popocatépetl recorded 21-88 daily emissions consisting of water vapor, gas, and ash. Crater incandescence was noted on some nights and increased in intensity with some emissions. Explosions occurred almost daily; an explosion at 2320 on 11 February ejected incandescent tephra onto the NE flank. The Alert Level remained at Yellow, Phase Two.
Geologic summary: Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5426 m 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 from Popocatépetl 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 precolumbian time.
Santa Maria, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m
INSIVUMEH reported that during 11-12 February weak explosions at Caliente cone, part of Santa María's Santiaguito lava-dome complex, generated ash plumes that drifted SW. Block avalanches from the E part of the crater reached vegetated areas. Ash plumes from explosions during 15-16 February rose 800 m above the crater and drifted SW.
Geologic summary: Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 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 westward-younging vents, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m
KVERT reported that during 5-12 February lava-dome extrusion onto Sheveluch’s N flank was accompanied by fumarolic activity, dome incandescence, ash explosions, and hot avalanches. 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.
3.17°N, 98.392°E, Summit elev. 2460 m
Based on satellite images, the Darwin VAAC reported that on 12 February ash plumes from Sinabung rose to altitudes of 3.4-5.2 km (11,000-17,000 ft) a.s.l. and drifted W and almost 30 km NE.
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.
12.602°N, 86.845°W, Summit elev. 1061 m
Based on satellite data, the Washington VAAC reported that on 13 February a gas plume possibly containing ash rose from Telica to an altitude of 1.8 (6,000 ft) a.s.l. and drifted WSW. On 16 February INETER reported that high micro-seismicity was associated with gas explosions.
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.
Tengger Caldera, Eastern Java (Indonesia)
7.942°S, 112.95°E, Summit elev. 2329 m
Based on satellite images and wind data, the Darwin VAAC reported that during 10-16 February ash plumes from Tengger Caldera's Bromo cone rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted in multiple directions.
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.
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