Active volcanoes in the world: January 21 - 27, 2015

Active volcanoes in the world: January 21 - 27, 2015

New activity was observed at 7 volcanoes from January 21 - 27, 2015. During the same period, ongoing activity was observed at 12 volcanoes.

New activity/unrest: Colima, Mexico | Hunga Tonga-Hunga Ha'apai, Tonga Islands | Karymsky, Eastern Kamchatka (Russia) | Klyuchevskoy, Central Kamchatka (Russia) | San Miguel, El Salvador | Sangay, Ecuador | Soputan, Sulawesi (Indonesia) | 

Ongoing activity: Aira, Kyushu (Japan) | Asosan, Kyushu (Japan) | Bagana, Bougainville (Papua New Guinea) | Bardarbunga, Iceland | Chirpoi, Kuril Islands (Russia) | Dukono, Halmahera (Indonesia) | Kilauea, Hawaiian Islands (USA) | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Sinarka, Shiashkotan Island (Russia) | Suwanosejima, Ryukyu Islands (Japan) | Zhupanovsky, Eastern Kamchatka (Russia)

New activity/unrest

Colima, Mexico
19.514°N, 103.62°W, Elevation 3850 m

Based on news articles, an explosion at 0713 on 21 January generated an ash plume that rose 4 km and drifted E. Ashfall was reported in Huescalpa (25 km NE), Tuxpan (25 km ENE), Zapotiltic (23 km NE), Vista Hermosa, Atenquique (20 km E), and Mazamitla (78 km NE). On 23 January authorities restricted access to the Parque Nacional Nevado de Colima citing increased activity during the previous days. The next day an ash plume rose 500 m and was followed by another ash plume that rose 700 m. Two ash plumes on 26 January rose as high as 1 km.

In a 24 January bulletin, the Unidad Estatal de Protección Civil reported that Colima remained active, although there was a slight decrease in the number and size of lava-block avalanches. Lava flows were active on the W and WNW flanks, and explosive activity was low to moderate. The recent explosions had partially destroyed the lava dome. Residents were warned not go within 5 km of the volcano.

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.

Hunga Tonga-Hunga Ha'apai, Tonga Islands
20.57°S, 175.38°W, Elevation 149 m

According to a news article from 26 January, the newly-formed island at Hunga Tonga-Hunga Ha'apai was about 120 m high, 1.5 km wide (N-S), and 2 km long (W-E). The island was an estimated 1 km in diameter with a crater that was 400-500 m in diameter. It had joined Hunga Ha’apai to the W and was 150-200 m short of joining Hunga Tonga to the N. The article noted that the eruption had decreased during the previous week; there were no longer emissions rising from the vent.

Geologic summary: The small islands of Hunga Tonga and Hunga Ha'apai cap a large seamount located about 30 km SSE of Falcon Island. The two linear andesitic islands are about 2 km long and represent the western and northern remnants of the rim of a largely submarine caldera lying east and south of the islands. Hunga Tonga and Hunga Ha'apai reach an elevation of only 149 m and 128 m above sea level, respectively, and display inward-facing sea cliffs with lava and tephra layers dipping gently away from the submarine caldera. A rocky shoal 3.2 km SE of Hunga Ha'apai and 3 km south of Hunga Tonga marks the most prominent historically active vent. Several submarine eruptions have occurred at Hunga Tonga-Hunga Ha'apai since the first historical eruption in 1912.

Karymsky, Eastern Kamchatka (Russia)
54.049°N, 159.443°E, Elevation 1513 m

KVERT reported that during 16-23 January a moderate eruption at Karymsky continued. Satellite images showed a thermal anomaly over the volcano during 18-22 January, and ash plumes that drifted 65 km E at an altitude of 5 km (16,400 ft) a.s.l. during 19-22 January.

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.

Klyuchevskoy, Central Kamchatka (Russia)
56.056°N, 160.642°E, Elevation 4754 m

KVERT reported that during 16-23 January a Strombolian and Vulcanian eruption at Klyuchevskoy continued. A lava flow effused onto the SE flank. Incandescence at the summit was visible and bombs were ejected 200-300 m above the crater. Explosions generated ash plumes that rose to altitudes of 6-7 km (19,700-23,000 ft) a.s.l.; ashfall was reported in Klyuchi Village (30 km NNE) on 21 January. Satellite images showed a daily, big, bright thermal anomaly over the volcano, and ash plumes drifting 210 km SW, NW, and NE at altitudes of 5-6 km (16,400-19,700 ft) a.s.l. The Aviation Color Code remained at Orange.

Geologic summary: Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

San Miguel, El Salvador
13.434°N, 88.269°W, Elevation 2130 m

SNET reported that at 0643 on 26 January a small explosion at San Miguel generated a plume that rose 300 m and quickly dissipated to the W. Local residents reported hearing rumbling and feeling tremor during the explosion. Minor ashfall was reported SW of the crater.

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.

Sangay, Ecuador
2.005°S, 78.341°W, Elevation 5286 m

Based on a pilot observation, the Washington VAAC reported that on 25 January an ash plume from Sangay rose to an altitude of 7.3 km (24,000 ft) a.s.l.Weather clouds prevented satellite image confirmation of the plume, although a thermal anomaly was detected which continued through the next day.

Geologic summary: The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador's volcanoes, and its most active. The dominantly andesitic volcano has been in frequent eruption for the past several centuries. The steep-sided, 5230-m-high glacier-covered volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. Sangay towers above the tropical jungle on the east side; on the other sides flat plains of ash from the volcano have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The more or less constant eruptive activity has caused frequent changes to the morphology of the summit crater complex.

Soputan, Sulawesi (Indonesia)
1.108°N, 124.73°E, Elevation 1784 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 21 January an ash plume from Soputan rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted over 35 km SW.

Geologic summary: The small 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 Sempu volcano. 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.

Ongoing activity

Aira, Kyushu (Japan)
31.593°N, 130.657°E, Elevation 1117 m

JMA reported that three explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 800 m during 19-23 January. Incandescence from the crater was visible at night on 22 January. Inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). The TokyoVAAC reported that on 23 January plumes rose to altitudes of 3-4.9 km (10,000-16,000 ft) a.s.l. and drifted SE. During 24-27 January plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE, E, NE, and N.

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.

Asosan, Kyushu (Japan)
32.884°N, 131.104°E, Elevation 1592 m

JMA reported that, based on seismicity and infrasound data, the eruption from Asosan’s Nakadake Crater that began on 25 November continued intermittently during 19-26 January. Incandescent material was sometimes ejected onto the crater rim. Plumes rose 1 km on 20 January and 600 m each day during 23-26 January. The Alert Level remained at 2 (on a scale of 1-5).

Geologic summary: The 24-km-wide Asosan caldera was formed during four major explosive eruptions from 300,000 to 90,000 years ago. These produced voluminous pyroclastic flows that covered much of Kyushu. The last of these, the Aso-4 eruption, produced more than 600 cu km of airfall tephra and pyroclastic-flow deposits. A group of 17 central cones was constructed in the middle of the caldera, one of which, Nakadake, is one of Japan's most active volcanoes. It was the location of Japan's first documented historical eruption in 553 AD. The Nakadake complex has remained active throughout the Holocene. Several other cones have been active during the Holocene, including the Kometsuka scoria cone as recently as about 210 CE. Historical eruptions have largely consisted of basaltic to basaltic-andesite ash emission with periodic strombolian and phreatomagmatic activity. The summit crater of Nakadake is accessible by toll road and cable car, and is one of Kyushu's most popular tourist destinations.

Bagana, Bougainville (Papua New Guinea)
6.137°S, 155.196°E, Elevation 1855 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 21 January ash plumes from Bagana rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 22-40 km NE. The next day ash plumes drifted almost 20 km SW.

Geologic summary: Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical, roughly 1850-m-high cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and 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. Satellite thermal measurements indicate a continuous eruption from before February 2000 through at least late August 2014.

Bardarbunga, Iceland
64.63°N, 17.53°W, Elevation 2009 m

During 21-27 January, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure. The lava field expanded along the N and NE margins. Seismicity remained strong and local air pollution from gas emissions persisted. Very high values of sulfur dioxide, about 84,000 µg/m3, were recorded at the eruption site on 21 January; this value was the highest recorded at ground level since the eruption started. Total subsidence of the Bárdarbunga surface since mid-August was 61 m, and the volume of erupted lava was an estimated 1.4 cubic kilometers. The lava field covered 84.7 square kilometers on 22 January. A report issued on 27 January stated that the average rate of lava emission during the previous three weeks was just less than 100 cubic meters per second, therefore the intensity of the eruption was slowly decreasing.

Geologic summary: The large central volcano of Bárdarbunga lies beneath the NW part of the Vatnajökull icecap, NW of Grímsvötn volcano, and contains a subglacial 700-m-deep caldera. Related fissure systems include the Veidivötn and Trollagigar fissures, which extend about 100 km SW to near Torfajökull volcano and 50 km NE to near Askja volcano, respectively. Voluminous fissure eruptions, including one at Thjorsarhraun, which produced the largest known Holocene lava flow on Earth with a volume of more than 21 cu km, have occurred throughout the Holocene into historical time from the Veidivötn fissure system. The last major eruption of Veidivötn, in 1477, also produced a large tephra deposit. The subglacial Loki-Fögrufjöll volcanic system located SW of Bárdarbunga volcano is also part of the Bárdarbunga volcanic system and contains two subglacial ridges extending from the largely subglacial Hamarinn central volcano; the Loki ridge trends to the NE and the Fögrufjöll ridge to the SW. Jökulhlaups (glacier-outburst floods) from eruptions at Bárdarbunga potentially affect drainages in all directions.

Chirpoi, Kuril Islands (Russia)
46.525°N, 150.875°E, Elevation 742 m

SVERT reported that satellite images over Snow, a volcano of Chirpoi, showed a thermal anomaly during 20-21 and 25 January. Cloud cover obscured views on other days during 19-26 January. 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.

Dukono, Halmahera (Indonesia)
1.68°N, 127.88°E, Elevation 1335 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 21-22 and 26 January ash plumes from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 45-55 km S and SW.

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.

Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Elevation 1222 m

During 21-27 January, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure. The lava field expanded along the N and NE margins. Seismicity remained strong and local air pollution from gas emissions persisted. Very high values of sulfur dioxide, about 84,000 µg/m3, were recorded at the eruption site on 21 January; this value was the highest recorded at ground level since the eruption started. Total subsidence of the Bárdarbunga surface since mid-August was 61 m, and the volume of erupted lava was an estimated 1.4 cubic kilometers. The lava field covered 84.7 square kilometers on 22 January. A report issued on 27 January stated that the average rate of lava emission during the previous three weeks was just less than 100 cubic meters per second, therefore the intensity of the eruption was slowly decreasing.

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.

Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Elevation 3283 m

KVERT reported that during 16-23 January lava-dome extrusion onto Sheveluch’s N flank was accompanied by incandescence, hot avalanches, and fumarolicactivity. Strong explosions during 18-21 January generated ash plumes that rose to altitudes of 6-7 km (19,700-23,000 ft) a.s.l. Satellite images detected ash plumes drifting more than 118 km ENE on 18 January and more than 530 km NE during 21-22 January. A thermal anomaly over the dome was detected daily. 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, Elevation 2857 m

AVO reported that on 21 January webcam images taken in partly cloudy conditions at Shishaldin possibly showed a dusting of fresh ash on the snowy upper flanks. During 21-22 January seismicity continued to be slightly elevated over background levels. Strongly elevated temperatures at the summit detected in overnight satellite images were consistent with possible lava in the crater. Clear webcam views during 23-25 January showed a small steam plume, indicating that the current activity was mostly contained in the deep summit crater. 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.

Sinarka, Shiashkotan Island (Russia)
48.875°N, 154.175°E, Elevation 934 m

SVERT reported that activity at Sinarka was not detected during January; on 26 January the Aviation Color Code was lowered to Green.

Geologic summary: Sinarka volcano, occupying the northern end of Shiashkotan Island in the central Kuriles, has a complex structure. A small, 2-km-wide depression open to the NW has been largely filled and overtopped by an andesitic postglacial central cone that itself contains a lava dome that forms the 934 m high point of the island. Another lava dome, Zheltokamennaya Mountain, lies 1.5 km to the SW along the buried SW rim of the caldera, and a smaller dome lies along the northern caldera rim. Historical eruptions have occurred at Sinarka during the 17th and 18th centuries. The last and largest of these, during 1872-78, was once thought to originate from Kuntomintar volcano at the southern end of the island, but is now attributed to Sinarka volcano (Gorshkov, 1970).

Suwanosejima, Ryukyu Islands (Japan)
29.638°N, 129.714°E, Elevation 796 m

Based on JMA notices, the Tokyo VAAC reported an explosion from Suwanosejima on 25 January.

Geologic summary: The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 persons live on the island.

Zhupanovsky, Eastern Kamchatka (Russia)
53.589°N, 159.15°E, Elevation 2899 m

KVERT reported that a moderate explosive eruption at Zhupanovsky continued during 16-23 January. Satellite images detected a thermal anomaly over the volcano during 17-20 January, and ash plumes drifting 300 km SW and E during 17-21 January. 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.

Source: GVP

Comments

No comments yet. Why don't you post the first comment?

Post a comment

Your name: *

Your email address: *

Comment text: *

The image that appears on your comment is your Gravatar