Active volcanoes in the world: June 4 - 10, 2014

Active volcanoes in the world: June 4 - 10, 2014

New activity/unrest was observed at 5 volcanoes from June 4 - 10, 2014. Ongoing activity was reported for 13 volcanoes.

New activity/unrest: Pavlof, United States  | San Miguel, El Salvador  | Sangeang Api, Indonesia  | Santa María, Guatemala  | Zhupanovsky, Eastern Kamchatka (Russia)

Ongoing activity: Aira, Kyushu (Japan)  | Bagana, Bougainville (Papua New Guinea)  | Batu Tara, Komba Island (Indonesia)  | Chirinkotan, Kuril Islands (Russia)  | Chirpoi, Kuril Islands (Russia)  | Dukono, Halmahera (Indonesia)  | Fuego, Guatemala  | Karymsky, Eastern Kamchatka (Russia)  | Kilauea, Hawaiian Islands (USA)  | Merapi, Central Java (Indonesia)  | Shishaldin, Fox Islands (USA)  | Shiveluch, Central Kamchatka (Russia)  | Ubinas, Peru

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, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail.

New activity/unrest

Pavlof, United States
55.42°N, 161.887°W, Summit elev. 2519 m

AVO reported that the Strombolian eruption at Pavlof continued during 3-10 June. On 3 June the FAA webcam showed a high steam plume rising above a vent on the NE flank and lower-level ash from pyroclastic flows on the N flank. During 3-4 June seismicity remained unchanged and persistent elevated surface temperatures were detected in satellite images. A steam plume with minor amounts of ash but rich in sulfur dioxide drifted 100 km W. Incandescence from lava fountaining was visible in webcam images on 4 June. According to a news article, flights in and out of Cold Bay and Unalaska were canceled on 4 June, affecting about 200 people.

Two strong explosions were detected by the seismic network at 0205 and 0245 on 5 June. Lightning was detected by the World Wide Lightning Location Network indicating the presence of ash; satellite images did not detected ash above the meteorological cloud tops at about 8.5 km (28,000 ft) a.s.l. A third event was detected at 0844. The level of activity declined during 5-6 June; ash emissions appeared to be greatly reduced although cloud cover continued to obscure satellite views. Elevated surface temperatures were observed in mostly cloudy satellite images during 8-9 June. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Geologic 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 of Pavlof took place in 1911, at the end of a 5-year-long eruptive episode. During this eruption a fissure opened on the northern flank of the volcano, ejecting large blocks and issuing lava flows.

San Miguel, El Salvador
13.434°N, 88.269°W, Summit elev. 2130 m

According to SNET in a report from 1 June, the Ministerio de Medio Ambiente y Recursos Naturales (MARN) reported that seismicity at San Miguel remained high. Locals observed more intense gas plumes rising from the crater with occasional and minor amounts of ash, especially after rain. Rumbling was also reported.

Geologic summary: The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. The unvegetated summit of the 2130-m-high volcano rises above slopes draped with coffee plantations. A broad, deep crater complex that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit of the towering volcano, which is also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic-andesitic volcano have fed a series of historical lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the north, NE, and SE sides. The SE-flank lava flows are the largest and form broad, sparsely vegetated lava fields crossed by highways and a railroad skirting the base of the volcano. The location of flank vents has migrated higher on the edifice during historical time, and the most recent activity has consisted of minor ash eruptions from the summit crater.

Sangeang Api, Indonesia
8.2°S, 119.07°E, Summit elev. 1949 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 4-7 June ash plumes from Sangeang Api rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 45-110 km W and NW.

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-tranchyandesitic volcanic cones, 1949-m-high Doro Api and 1795-m-high Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century.

Santa María, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m

On 6 June INSIVUMEH reported that the Santiaguito Observatory (OBSAN) was seriously affected by a large lahar that descended the Nima I river drainage on the S flank of Santa María's Santiaguito lava-dome complex. The lahar came in waves, 5-9 m high, was 80 m wide, and carried blocks up to 5 m in diameter. It overtopped the river banks and flowed to a nearby farm. The staff working at OBSAN had to evacuate; some important scientific equipment was lost and damaged. On 7 June a lahar descended the Samala river, a tributary of the Nima I river, carrying blocks up to 1 m in diameter, and lahars in the Nima I drainage had a sulfur odor. During 7-8 June slow-moving lava flows descended the E flank. Explosions during 8-9 June generated ash plumes that rose 500 m and drifted SW. Large avalanches in the collapsed area were incandescent at night. During 9-10 June explosions generated white and gray plumes that rose 500 m, the lava flows on the E flank produced avalanches, and Domo del Brujo began degassing.

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 of Volcán Santa María 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.

Zhupanovsky, Eastern Kamchatka (Russia)
53.59°N, 159.147°E, Summit elev. 2958 m

KVERT reported that an eruption at Zhupanovsky began on 6 June, producing an ash plume that rose to an altitude of 6 km (19,900 ft) a.s.l., as suggested by Tokyo VAAC and UHPP notices. Cloud cover prevented views from satellite. The Aviation Color Code was raised to Yellow. Satellite images on 9 June showed ash plumes rising to altitudes of 3-4 km (9,800-13,100 ft) a.s.l. and drifting 60 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 of Zhupanovsky 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

JMA reported that during 19-23 May two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra that landed as far as 1,300 m away. Incandescence from the crater was detected at night during 19-20 May. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 6 and 9 June plumes rose to altitudes of 2.1-5.5 km (7,000-18,000 ft) a.s.l. Plumes drifted NW on 9 June.

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.

Bagana, Bougainville (Papua New Guinea)
6.14°S, 155.195°E, Summit elev. 1750 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 10 June an ash plume from Bagana rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted over 35 km SW.

Geologic summary: Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical, roughly 1750-m-high lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is frequent and is characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50-m-thick with prominent levees that descend the volcano's flanks on all sides.

Batu Tara, Komba Island (Indonesia)
7.792°S, 123.579°E, Summit elev. 748 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 6 June an ash plume from Batu Tara rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 150 km NW. During 7-9 June ash plumes rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted over 35 km NW and W.

Geologic summary: The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (fomerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow.

Chirinkotan, Kuril Islands (Russia)
48.98°N, 153.48°E, Summit elev. 724 m

SVERT reported that an eruption at Chirinkotan had begun on 24 May; thermal anomalies and gas emissions sometimes containing ash were detected in satellite images. On 5 June seldom and weak thermal anomalies suggested cooling lava flows. The Aviation Color Code was lowered to Green.

Geologic summary: The small, mostly unvegetated 3-km-wide island of Chirinkotan occupies the far end of an E-W-trending volcanic chain that extends nearly 50 km west of the central part of the main Kuril Islands arc. Chirinkotan is the emergent summit of a volcano that rises 3000 m from the floor of the Kuril Basin. A small 1-km-wide caldera about 300-400 m deep is open to the SE. Lava flows from a cone within the breached crater reached the north shore of the island. Historical eruptions have been recorded at Chirinkotan since the 18th century. Fresh lava flows also descended the SE flank of Chirinkotan during an eruption in the 1880s that was observed by the English fur trader Captain Snow.

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

In a 5 June report, SVERT summarized activity at Snow, a volcano of Chirpoi, over the previous two years: an effusive eruption started on 10 November 2012, producing steam-and-gas emissions and thermal anomalies thorough April 2013; the volcano was quiet; steam-and-gas emissions and thermal anomalies were again detected starting on 12 July 2013, suggesting a new period of lava effusion. Weak thermal anomalies during 2-4 June implied cooling lava flows. The Aviation Color Code was lowered to Green.

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. Two volcanoes on Chirpoi Island have been historically active. 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.

Dukono, Halmahera (Indonesia)
1.68°N, 127.88°E, Summit elev. 1335 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 4 June an ash plume from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 150 km N. The next day an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 55 km NW. On 9 June ash plumes rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted 25-30 km NW.

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. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

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

INSIVUMEH reported that on 5 June lahars descended Fuego's Honda (E), El Jute (SE), Ceniza (SSW), and Santa Teresa (S) drainages, carrying blocks as large as 1.5 m in diameter. Explosions during 5-6 June generated ash plumes that rose 250-350 m and drifted 8-10 km W and NW. Explosions during 8-10 June generated ash plumes that rose 350-750 m and drifted 8-10 km N. Incandescent material ejected 100 m above the crater landed on the flank and formed avalanches. On 9 June lahars in the El Jute and Las Lajas drainages carried blocks up to 1.5 m in diameter.

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 volcano dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta volcano 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 volcano, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

Karymsky, Eastern Kamchatka (Russia)
54.05°N, 159.45°E, Summit elev. 1536 m

KVERT reported that Strombolian and weak Vulcanian activity continued at Karymsky during 30 May-6 June. Satellite images detected no activity or were obscured by clouds. 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, which is located immediately south of Karymsky volcano. The caldera enclosing Karymsky volcano formed about 7600-7700 radiocarbon years ago; construction of the Karymsky 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

During 4-10 June HVO reported that the circulating lava lake occasionally rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Gas emissions remained elevated. The plume from the vent continued to deposit variable amounts of ash, spatter, and Pele's hair onto nearby areas; smaller particles may have been dropped several kilometers away.

At Pu'u 'O'o Crater, glow emanated from spatter cones on the N, SE, and S portions of the crater floor, and from a small lava lake in the NE spatter cone. On 22 May geologists mapped the farthest point of activity from the Kahauale’a 2 lava flow, 8.4 km NE of Pu’u 'O'o, and on 6 June they mapped four small breakouts as far as 6.5 km from Pu’u 'O'o. Smoke plumes rising from forested areas suggested advancing breakout flows.

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.

Merapi, Central Java (Indonesia)
7.542°S, 110.442°E, Summit elev. 2968 m

PVMBG reported that during 30 May-5 June seismicity at Merapi fluctuated at normal levels and declined as compared to the previous two weeks. Deformation measurements showed no significant changes. Solfatara plumes rose 400 m and drifted W on 31 May. The Alert Level remained at 1 (on a scale of 1-4).

Geologic summary: Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. Merapi is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi volcano beginning during the Pleistocene ended with major edifice collapse perhaps about 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the volcano's western-to-southern flanks and caused many fatalities during historical time. The volcano is the object of extensive monitoring efforts by the Merapi Volcano Observatory.

Shishaldin, Fox Islands (USA)
54.756°N, 163.97°W, Summit elev. 2857 m

AVO reported that, although cloud cover frequently obscured views of Shishaldin during 4-9 June, seismicity indicated that the low-level eruption continued. Elevated surface temperatures at the summit were detected in mostly cloudy satellite images during 7-9 June. 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, Shishaldin 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. Shishaldin contains 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.

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

KVERT reported that during 30 May-6 June lava-dome extrusion onto Shiveluch’s SE flank was accompanied by ash explosions, incandescence, hot avalanches, and fumarolic activity. Satellite images detected a thermal anomaly over the dome on 31 May and 1 and 3 June. The Aviation Color Code remained at Orange.

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

Ubinas, Peru
16.355°S, 70.903°W, Summit elev. 5672 m

In a press release from 5 June, IGP's Observatorio Volcanologico de Arequipa (IGP-OVA) and Observatorio Vulcanológico del INGEMMET (OVI) reported that an Alert Level Orange continued for residents affected by the Ubinas eruption. Residents of Querapi and Tonohaya remained evacuated. The report noted that a significant and continuous release of ash emissions and gasses were observed during the previous days. Gas-and-ash plumes observed during 5-7 June rose 0.2-2 km above the crater. Minor ashfall was reported in Lloque and Yungas during 6-7 June.

Geologic summary: A small, 1.4-km-wide caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. Ubinas 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 volcano was followed by construction of Ubinas II volcano 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 of Ubinas about 3700 years ago extend 10 km from the volcano. Widespread plinian pumice-fall deposits from Ubinas include one of Holocene age about 1000 years ago. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.

Source: GVP

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