New activity/unrest was observed at 2 volcanoes from November 4 – 10, 2015. During the same period, ongoing activity was reported for 18 volcanoes.
New activity/unrest: Fuego, Guatemala | Rinjani, Lombok Island (Indonesia).
Ongoing activity: Aira, Kyushu (Japan) | Colima, Mexico | Cotopaxi, Ecuador | Dukono, Halmahera (Indonesia) | Gamalama, Halmahera (Indonesia) | Gamkonora, Halmahera (Indonesia) | Ibu, Halmahera (Indonesia) | Karangetang, Siau Island (Indonesia) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaiian Islands (USA) | Lokon-Empung, Sulawesi (Indonesia) | Paluweh, Indonesia | Sangeang Api, Indonesia | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Sinabung, Indonesia | Tungurahua, Ecuador | Ubinas, Peru.
14.473°N, 90.88°W, Summit elev. 3763 m
INSIVUMEH reported that during 5-6 and 8-10 November explosions at Fuego generated ash plumes that rose 550-750 m above the crater and drifted 10-15 km S and SE. Ashfall was reported in Panimache I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), and El Porvenir (8 km ENE), and Sangre de Cristo. Incandescent material was ejected 200 m high and produced avalanches that descended the Santa Teresa, Trinidad, and Las Lajas (S) drainages. During 8-9 November a new lava flow traveled 1.5 km down the Las Lajas and El Jute (SE) drainages. By 10 November the lava flow was 2.5 km long. Incandescent material was ejected 300 m high, and ashfall was reported in Panimache I and II, Morelia, Santa Sofia, El Porvenir, Sangre de Cristo and the municipality of San Pedro Yepocapa. Later that evening pyroclastic flows descended the E flank. Ash fell in multiple areas including Morelia, Santa Sofía, el Porvenir, Panimache II, Sangre de Cristo, San Pedro Yepocapa, Rochela, Ceilán, San Andrés Osuna, El Zapote, Siquinala, Santa Lucia Cotzumalguapa, Mazatenango, Patulul, and Cocales.
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.
Rinjani, Lombok Island (Indonesia)
8.42°S, 116.47°E, Summit elev. 3726 m
PVMBG reported that after an eruption occurred at Rinjani on 25 October tremor amplitude increased, and was continuous from 1109 on 2 November through 0600 on 5 November. During 25-31 October dense white emissions rose 900 m above Barujari Crater. During 1-5 November dense gray-to-brown ash plumes rose as high as 1.6 km above the crater. The webcam showed incandescent material being ejected from the crater on 4 November. The Alert Level remained at 2 (on a scale of 1-4); visitors and residents were warned not to approach the crater within a 3-km radius. Based on a 9-November PVMBG notice, BNPB reported that a lava flow had traveled 1 km E of the crater, towards the Koko Putih River. Incandescent material was ejected 750 m above the crater and ash plumes rose 2.5 km. Based on satellite observations and pilot observations, the Darwin VAAC reported that during 4-10 November ash plumes rose to altitudes of 4.3-6.1 km (14,000-20,000 ft) a.s.l. and drifted as far as 740 km NW, W, SW, and S.
According to news articles, Ngurah Rai International Airport in Bali reopened on 9 November but some international flights had remained canceled; the airport had closed the evening before. The closure of Lombok International Airport had been extended until 10 November.
Geologic summary: Rinjani volcano on the island of Lombok rises to 3726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the east, but the west side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak (Samalas) caldera. The caldera formed during one of the largest Holocene eruptions globally in 1257 CE, which truncated Samalas stratovolcano. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the east end of the caldera. Historical eruptions dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m
JMA reported that during 2-6 November two small-scale eruptions occurred at Showa Crater, at Aira Caldera’s Sakurajima volcano. 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.
19.514°N, 103.62°W, Summit elev. 3850 m
Based on satellite images, wind data, and notices from Colima Towers and the Mexico City MWO, the Washington VAAC reported that during 4-7 and 9 November ash plumes from Colima rose to altitudes of 4.9-6 km (16,000-20,000 ft) a.s.l. and drifted 13-24 km N, NW, W, SW, and S. On 10 November emissions released about every two hours rose to an altitude of 5.7 (19,000 ft) a.s.l. and drifted SW and WSW.
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.
0.677°S, 78.436°W, Summit elev. 5911 m
IG reported that during 4-10 November gas, steam, and ash plumes rose almost daily from Cotopaxi as high as 1.5 km above the crater. Minor ashfall was reported S of the volcano on 6 November, and small lahars descended the W flank during 6 and 8-9 November.
Geologic summary: Symmetrical, glacier-clad Cotopaxi stratovolcano is Ecuador's most well-known volcano and one of its most active. The steep-sided cone is capped by nested summit craters, the largest of which is about 550 x 800 m in diameter. Deep valleys scoured by lahars radiate from the summit of the andesitic volcano, and large andesitic lava flows extend as far as the base of Cotopaxi. The modern conical volcano has been constructed since a major edifice collapse sometime prior to about 5000 years ago. Pyroclastic flows (often confused in historical accounts with lava flows) have accompanied many explosive eruptions of Cotopaxi, and lahars have frequently devastated adjacent valleys. The most violent historical eruptions took place in 1744, 1768, and 1877. Pyroclastic flows descended all sides of the volcano in 1877, and lahars traveled more than 100 km into the Pacific Ocean and western Amazon basin. The last significant eruption of Cotopaxi took place in 1904.
Dukono, Halmahera (Indonesia)
1.68°N, 127.88°E, Summit elev. 1335 m
PVMBG reported that during 1 August-3 November white-and-gray plumes rose as high as 1 km above the rim of Dukono's Malupang Warirang crater and were accompanied by rumbling and roaring. Ashfall was reported in areas from the Galela District to Tobelo town (NNW) in August and at the Dukono observation post in September. Seismicity fluctuated at high levels, with elevated periods during 15-22 August, 28 August-5 September, and 15-25 October. The Alert Level remained at 2 (on a scale of 1-4). Residents and tourists were advised not to approach the crater within a radius of 2 km.
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 4-10 November ash plumes rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 25-130 km N, NW, W, SW, and S.
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.
Gamalama, Halmahera (Indonesia)
0.8°N, 127.33°E, Summit elev. 1715 m
PVMBG reported that during 1 August-4 November seismicity at Gamalama fluctuated, and was dominated by hybrid earthquakes and signals indicating emissions. Three periods of increased seismicity were recorded during 3-5 and 11-19 August, and 8-22 October, though seismicity declined overall.
A sudden, small eruption from a fissure on the NW flank occurred at 1953 on 8 September with no precursory seismicity, and produced a plume that rose 1 km. Gray plumes rose from 300-600 m the vent during 9-24 September. White plumes rose from Main Crater and fissures on the E and NW flanks as high as 200 m during 1 October-3 November. The Alert Level remained at 2 (on a scale of 1-4); visitors and residents were warned not to approach the crater within a 1.5-km radius.
Geologic summary: Gamalama (Peak of Ternate) is a near-conical stratovolcano that comprises the entire island of Ternate off the western coast of Halmahera and is one of Indonesia's most active volcanoes. The island of Ternate was a major regional center in the Portuguese and Dutch spice trade for several centuries, which contributed to the thorough documentation of Gamalama's historical activity. Three cones, progressively younger to the north, form the summit of Gamalama, which reaches 1715 m. Several maars and vents define a rift zone, parallel to the Halmahera island arc, that cuts the volcano. Eruptions, recorded frequently since the 16th century, typically originated from the summit craters, although flank eruptions have occurred in 1763, 1770, 1775, and 1962-63.
Gamkonora, Halmahera (Indonesia)
1.38°N, 127.53°E, Summit elev. 1635 m
PVMBG reported that observers at the Gamkonora observation post in Gamsungi (6 km NW), West Halmahera, reported that during 1 August-3 November diffuse white plumes rose up to 70 m above the crater rim. RSAM values fluctuated; an increase was detected in October coincident with a period of increased tremor. The Alert Level was lowered to 2 (on a scale of 1-4) on 1 July. Residents and tourists were asked not to venture near the crater within a radius of 1.5 km.
Geologic summary: The shifting of eruption centers on Gamkonora, at 1635 m the highest peak of Halmahera, has produced an elongated series of summit craters along a N-S trending rift. Youthful-looking lava flows originate near the cones of Gunung Alon and Popolojo, south of Gamkonora. Since its first recorded eruption in the 16th century, Gamkonora has typically produced small-to-moderate explosive eruptions. Its largest historical eruption, in 1673, was accompanied by tsunamis that inundated villages.
Ibu, Halmahera (Indonesia)
1.488°N, 127.63°E, Summit elev. 1325 m
PVMBG reported that during 1 August-3 November white-to-gray plumes rose as high as 500 m above Ibu’s craters. Seismicity was dominated by signals indicating surface or near-surface activity, and the continued growth of the lava dome. The Alert Level remained at 2 (on a scale of 1-4). The public was warned to stay at least 2 km away from the active crater, and 3.5 km away from the N side.
Geologic 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.
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 during 28 October-4 November that activity remained stable. The lava dome was incandescent at night and produced a lava flow that traveled 200 m S. Incandescent avalanches from the lava-flow front traveled as far as 2 km E down the Batuawang and Kahetang drainages. Seismicity decreased, but continued to be dominated by avalanche signals. 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 1784-m-high stratovolcano contains five summit craters along a N-S line. Karangetang 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 30 October-6 November. Satellite images showed ash plumes drifting 40 km NE on 2 November and 96 km SE on 4 November at an altitude of 2.5 km (8,000 ft) a.s.l. 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 4-10 November. The lava lake continued to circulate and spatter in the Overlook vent. The June 27th NE-trending lava flow continued to be active within 2.2-6.4 km NE of Pu'u 'O'o Crater.
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.
Lokon-Empung, Sulawesi (Indonesia)
1.358°N, 124.792°E, Summit elev. 1580 m
Although inclement weather sometimes obscured views of Lokon-Empung's Tompaluan Crater, PVMBG reported that during 28 October-5 November observers at the post in Kakaskasen Tomohon (North Sulawesi, 4 km from the crater), saw white plumes rising as high as 125 m above the crater. Seismicity fluctuated, but the seismic spectral amplitude measurement (SSAM) showed an increasing trend. The Alert Level remained at 3 (on a scale of 1-4). Residents and tourists were reminded not to approach the crater within a radius of 2.5 km.
Geologic summary: The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2 km apart), has a flat, craterless top. The morphologically younger Empung volcano to the NE has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m wide double crater situated in the saddle between the two peaks. Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred. A ridge extending WNW from Lokon includes Tatawiran and Tetempangan peak, 3 km away.
8.32°S, 121.708°E, Summit elev. 875 m
PVMBG reported that observers at a post located in Kampung Ropa, Keliwumbu Village, noted that during 1 August-2 November diffuse white plumes rose as high as 200 m above Paluweh. Seismicity remained relatively stable. The Alert Level remained at 2 (on a scale of 1-4). Residents and tourists were reminded not to approach the summit within a radius of 1.5 km.
Geologic summary: Paluweh volcano, also known as Rokatenda, forms the 8-km-wide island of Paluweh north of the volcanic arc that cuts across Flores Island. Although the volcano rises about 3000 m above the sea floor, its summit reaches only 875 m above sea level. The broad irregular summit region contains overlapping craters up to 900 m wide and several lava domes. Several flank vents occur along a NW-trending fissure. The largest historical eruption occurred in 1928, when strong explosive activity was accompanied by landslide-induced tsunamis and lava dome emplacement.
Sangeang Api, Indonesia
8.2°S, 119.07°E, Summit elev. 1949 m
PVMBG reported that observers at the Sangeang Api observation post in Desa Sangeang Darat, Bima, West Nusa Tenggara, reported that during 1 July-30 September diffuse white plumes rose up to 250 m above the crater rim. During 1 October-1 November white-to-gray plumes rose as high as 350 m. Beginning on 23 October occasional weak thumping noises were reported. Crater incandescence possibly indicated lava-dome growth or lava-flow advancement. The Alert Level remained at 2 (on a scale of 1-4); visitors and residents were warned not to approach the crater within a 1.5-km radius.
Geologic 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-
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m
KVERT reported that during 30 October-6 November lava-dome extrusion onto Sheveluch’s N flank was accompanied by fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images detected an intense daily thermal anomaly over the dome. Explosions and hot avalanches generated ash plumes that rose to an altitude of 3.5 km (11,500 ft) a.s.l. and drifted about 30 km SE on 3 and 5 November. 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.
Shishaldin, Fox Islands (USA)
54.756°N, 163.97°W, Summit elev. 2857 m
AVO reported that seismicity at Shishaldin continued to be slightly elevated over background levels during 4-10 November, indicating that low-level eruptive activity confined to the summit crater continued. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.
Geologic summary: The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." A steady steam plume rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the west and NE sides at 1500-1800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century.
3.17°N, 98.392°E, Summit elev. 2460 m
Based on information from PVMBG, the Darwin VAAC reported that on 6 November an ash plume from Sinabung rose to an altitude of 4.6 km (15,000 ft) a.s.l. A pyroclastic flow was visible on 8 November; an ash plume was generated but the altitude was unable to be determined due to a weather cloud in the area.
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.
1.467°S, 78.442°W, Summit elev. 5023 m
IG reported high seismic activity at Tungurahua during 4-10 November, characterized by long-period events, volcano-tectonic events, an explosion, and signals indicating emissions; cloud cover often prevented visual observations. When occasionally visible, steam, gas, and ash plumes rose as high as 700 m, and drifted W, NE, and E. On 7 November a lahar in Chontapamba carried blocks 1 m in diameter and caused a road closure between Baños and Penipe. Nighttime crater incandescence was visible during 8-9 November, and ash fell in Choglontús, Manzano, and Palitahua on 9 November.
Geologic summary: Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the west, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater, accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Baños at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.
16.355°S, 70.903°W, Summit elev. 5672 m
Instituto Geofísico del Perú (IGP) Observatorio Volcanológico del Sur (OVS) reported that during 3-9 November ash-and-gas emissions rose above Ubinas. A moderate explosion detected at 1216 on 5 November generated an ash plume that rose 2.2 km. Thermal anomalies were detected on 3, 5, and 8 November.
Geologic summary: A small, 1.4-km-wide caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Perú. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3700 years ago extend 10 km from the volcano. Widespread plinian pumice-fall deposits include one of Holocene age about 1000 years ago. Holocene lava flows are visible on the flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.
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