New activity was observed at 7 volcanoes from January 28 - February 3, 2015. During the same period, ongoing activity was observed at 13 volcanoes.
New activity/unrest: Colima, Mexico | Etna, Sicily (Italy) | Karymsky, Eastern Kamchatka (Russia) | Klyuchevskoy, Central Kamchatka (Russia) | Pacaya, Guatemala | Ruapehu, North Island (New Zealand) | Soputan, Sulawesi (Indonesia)
Ongoing activity: Aira, Kyushu (Japan) | Asosan, Kyushu (Japan) | Bardarbunga, Iceland | Chirinkotan, Kuril Islands (Russia) | Chirpoi, Kuril Islands (Russia) | Karangetang [Api Siau], Siau Island (Indonesia) | Kilauea, Hawaiian Islands (USA) | Manam, Papua New Guinea | Reventador, Ecuador | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Zhupanovsky, Eastern Kamchatka (Russia)
19.514°N, 103.62°W, Summit elev. 3850 m
Based on webcam views and satellite images, the Washington VAAC reported that on 29 January a brief emission from Colima with low ash content drifted 30 km SW. The next day a few brief emissions rose from the crater and dissipated about 37 km SW. In a 2 February 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 on the SW and WNW flanks minimally advanced, and small landslides of lava blocks were observed. 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.
Etna, Sicily (Italy)
37.734°N, 15.004°E, Summit elev. 3330 m
INGV reported that a new eruptive episode at Etna began on 31 December and lasted through the morning of 2 February. Poor meteorological conditions prevented views of the summit area during the first 36 hours of the eruption. During improved viewing conditions on the evening of 1 February, volcanologists observed Strombolian activity from a single vent in the saddle between the cones of the Southeast Crater (SEC). Explosions occurred every few seconds and ejected incandescent bombs 200 m high. At the same time a vent at the base of the southern SEC cone issued a lava flow that traveled 2 km S, dividing into two branches. At dawn on 2 February the Strombolian activity produced a dense ash cloud that drifted E. At about 0550 emissions stopped and volcanic tremor suddenly decreased.
Geologic summary: Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater (the latter formed in 1978). Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.
Karymsky, Eastern Kamchatka (Russia)
54.049°N, 159.443°E, Summit elev. 1513 m
KVERT reported that during 23-30 January a moderate explosive eruption at Karymsky continued. Satellite images showed a daily thermal anomaly over the volcano, and ash plumes that rose 3.5-4 km above the crater and drifted 160 km E and N during 21-23 and 27 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, Summit elev. 4754 m
KVERT reported that during 23-30 January a Strombolian and Vulcanian eruption at Klyuchevskoy continued. 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) and near the Khapitsa River on 27 January, and in Kozyrevsk Village (50 km W) on 28 January. A lava flow effused onto the E flank; phreatic explosions at the lava flow front produced gas-and-steam clouds with minor amounts of ash that rose 7-8 km (23,000-26,200 ft) a.s.l. during 27-28 January. Satellite images showed a daily, big, bright thermal anomaly over the volcano, and ash-and-gas plumes drifting 300 km W, N, NE, E, and SE at altitudes of 5.5-7 km (18,000-23,000 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.
14.381°N, 90.601°W, Summit elev. 2552 m
In a special notice INSIVUMEH reported that on 28 January ash emissions originating from Pacaya's Mackenney Crater drifted 4 km S and SW. During field observations, scientists saw a defined central crater, 40-50 m in diameter, and ash emissions. Gas plumes rose from an area on the S flank. Seismic data was characterized by tremor and low-frequency events. In a report from 1 February, INSIVUMEH stated that low-altitude water vapor plumes with minor amounts of ash drifted W and SW. During 1-2 February fumarolic plumes rose 50 m and drifted 600 m S.
Geologic summary: Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex basaltic volcano constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo volcano between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity at Pacaya has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.
Ruapehu, North Island (New Zealand)
39.28°S, 175.57°E, Summit elev. 2797 m
On 30 January, GeoNet reported that water temperatures of Ruapehu's summit Crater Lake had been increasing since early December 2014, rising from 15 degrees Celsius to over 40. Similar temperatures were recorded in March 2011 and April 2014, before the lake cooled.
Data from a field visit on 14 January showed increased amounts of volcanic gas emissions through the lake. Other recent observations from pilots and field visits confirmed that the lake changed color from blue green to light gray due to lake convection. A GeoNet volcanologist noted that lake temperature cycling was not unusual; five heating cycles have been detected since 2010. The Aviation Colour Code remained at Green and the Volcanic Alert Level remained at 1 (signs of volcano unrest).
Geologic summary: Ruapehu, one of New Zealand's most active volcanoes, is a complex stratovolcano constructed during at least four cone-building episodes dating back to about 200,000 years ago. The 110 cu km dominantly andesitic volcanic massif is elongated in a NNE-SSW direction and surrounded by another 100 cu km ring plain of volcaniclastic debris, including the Murimoto debris-avalanche deposit on the NW flank. A series of subplinian eruptions took place between about 22,600 and 10,000 years ago, but pyroclastic flows have been infrequent. A single historically active vent, Crater Lake, is located in the broad summit region, but at least five other vents on the summit and flank have been active during the Holocene. Frequent mild-to-moderate explosive eruptions have occurred in historical time from the Crater Lake vent, and tephra characteristics suggest that the crater lake may have formed as early as 3000 years ago. Lahars produced by phreatic eruptions from the summit crater lake are a hazard to a ski area on the upper flanks and to lower river valleys.
Soputan, Sulawesi (Indonesia)
1.108°N, 124.73°E, Summit elev. 1784 m
Based on statements from PVMBG, the Darwin VAAC reported that on 2 February an ash plume from Soputan rose to an altitude of 6.1 km (20,000 ft) a.s.l. A thermal anomaly was visible in satellite images; ash was not visible at the reported altitude, but possible ash was detected to the N at 3 km (10,000 ft) a.s.l.
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.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m
The Tokyo VAAC reported that during 28 January-3 February plumes from Aira Caldera’s Sakurajima volcano rose to altitudes of 1.5-3.3 km (5,000-11,000 ft) a.s.l. and drifted NE, E, SE, and S. On 1 February pilots observed ash plumes that rose to altitudes of 2.7-3.3 km (9,000-11,000 ft) a.s.l. JMA reported that nine explosions from Showa Crater ejected tephra as far as 1,800 m during 26-30 January. Incandescence from the crater was visible at night, and inflation continued to be detected. An explosion on 30 January caused tephra fall (2 cm in diameter) in Kagoshima Kurokami (3.5 km E). The Alert Level remained at 3 (on a scale of 1-5).
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, Summit elev. 1592 m
JMA reported that, based on seismicity and infrasound data, the eruption from Asosan’s Nakadake Crater that began on 25 November 2014 continued intermittently during 26-30 January. Incandescent material was sometimes ejected onto the crater rim, and plumes rose 800 m above the crater. High-amplitude tremor continued. 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.
64.63°N, 17.53°W, Summit elev. 2009 m
During 27 January-3 February, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure, with a lava-flow rate of about 100 cubic meters per second. Seismicity remained strong and local air pollution from gas emissions persisted. GPS measurements showed that subsidence continued. On 27 January the plume rose an estimated 1.3 km. A map made on 21 January showed that the lava field was thickening and not expanding significantly; the erupted volume was an estimated 1.4 cubic kilometers (15% uncertainty).
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.
Chirinkotan, Kuril Islands (Russia)
48.98°N, 153.48°E, Summit elev. 724 m
SVERT reported that weak steam-and-gas emissions from Chirinkotan were detected in satellite images on 31 January. Cloud cover obscured views on the other days during 26 January-2 February. The Aviation Color Code remained at Yellow.
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
SVERT reported that satellite images over Snow, a volcano of Chirpoi, showed a weak thermal anomaly on 26 January. Cloud cover obscured views during 27 January-2 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.
Karangetang [Api Siau], Siau Island (Indonesia)
2.78°N, 125.4°E, Summit elev. 1784 m
According to a news article, heavy rains on 22 January triggered lahars that descended Karangetang's flanks, overflowed ravines, and damaged some public and private buildings. Some traffic disruptions were also reported.
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.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Summit elev. 1222 m
During 28 January-3 February HVO reported that Kilauea’s 27 June NE-trending lava flow continued to widen and breakout lava flows continued upslope of the leading front. The most northern lobe of lava was about 500 m above Highway 130 by 3 February, near police and fire stations. At Pu'u 'O'o Crater, glow emanated from several outgassing openings in the crater floor. The circulating lava lake occasionally rose and fell in the deep pit within Halema'uma'u Crater. Gas emissions remained elevated. The plume from the vent continued to deposit variable amounts tephra onto nearby areas.
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.
Manam, Papua New Guinea
4.08°S, 145.037°E, Summit elev. 1807 m
RVO reported that activity at both Manam's Southern Crater and Main Crater was low during 1-31 January; diffuse white vapor emissions were observed rising from both craters during brief clear views. Incandescence from Main Crater fluctuated from weak to bright during 19 and 23-27 January.
Geologic summary: The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys" channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.
0.077°S, 77.656°W, Summit elev. 3562 m
IG reported moderate seismic activity including explosions, long-period earthquakes, harmonic tremor, and tremor at Reventador during 28 January-3 February. Cloudy conditions obscured views of the summit most of the time. On 28 January a steam plume with low ash content rose 1 km above the crater and drifted W. During 29-30 January steam plumes with minor amounts of ash rose 400-500 m and drifted SW and S.
Geologic summary: Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.
Santa Maria, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m
INSIVUMEH reported that during 31 January-1 February explosions from Caliente cone, part of Santa María's Santiaguito lava-dome complex, generated ash plumes that rose 500 m and drifted WSW, causing ashfall in the Palajunoj area. The lava flow on the SE flank was incandescent and produced avalanches that descended the SE and E flanks. An explosion on 13 January generated an ash plume that rose 700 m and drifted SW. Block avalanches originated from Caliente cone. Explosions the next day produced plumes that drifted SW. Explosions during 2-3 February generated ash plumes that rose 500 m and drifted SE. The lava flow remained active.
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 23-30 January lava-dome extrusion onto Sheveluch’s N flank was accompanied by incandescence, hot avalanches, and fumarolic activity. Strong explosions on 21, 26, and 29 January generated ash plumes that rose to altitudes of 4-7.5 km (13,100-24,600 ft) a.s.l. Satellite images detected ash plumes drifting more than 500 km NW, NE, and E during 21-22, 26-27, and 29 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, Summit elev. 2857 m
AVO reported that seismicity at Shishaldin continued to be slightly elevated over background levels during 28 January-3 February. Nothing significant was observed in mostly cloudy satellite and web camera images, although minor steaming from the summit was recorded by the webcam during 30 January-3 February. During 31 January-3 February elevated surface temperatures were observed in satellite images, and during 1-2 February low-level ash emissions drifted WSW. 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.
Zhupanovsky, Eastern Kamchatka (Russia)
53.589°N, 159.15°E, Summit elev. 2899 m
KVERT reported that a moderate explosive eruption at Zhupanovsky continued during 23-30 January. Satellite images detected ash plumes drifting 160 km SW and SE at altitudes of 5-6 km (16,400-19,700 ft) a.s.l. during 22 and 25-26 January, and a thermal anomaly over the volcano during 23 and 25-27 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.