New activity was observed at 5 volcanoes from January 7 - 13, 2015. During the same period, ongoing activity was reported for 16 volcanoes.
New activity/unrest: Chirpoi, Kuril Islands (Russia) | Colima, Mexico | Etna, Sicily (Italy) | Hunga Tonga-Hunga Ha'apai, Tonga Islands | Klyuchevskoy, Central Kamchatka (Russia)
Ongoing activity: Aira, Kyushu (Japan) | Asosan, Kyushu (Japan) | Bardarbunga, Iceland | Chirinkotan, Kuril Islands (Russia) | Fogo, Cape Verde | Fuego, Guatemala | Kilauea, Hawaiian Islands (USA) | Kuchinoerabujima, Ryukyu Islands (Japan) | Nevado del Ruiz, Colombia | Popocatepetl, Mexico | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Sinabung, Indonesia | Sinarka, Shiashkotan Island (Russia) | Zhupanovsky, Eastern Kamchatka (Russia)
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 10-11 January. Cloud cover obscured views on other days during 5-12 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.
19.514°N, 103.62°W, Elevation 3850 m
Based on news articles, an explosion from Colima at about 0900 on 3 January generated an ash plume that rose 3 km. Ash fell in the municipalities of Zapotlán El Grande (26 km NE), Gómez Farías (34 km NNE), Concepción de Buenos Aires (63 km NE), Manzanilla de la Paz (72 km NE), Toliman (31 km WNW), Tuxpan (25 km ENE), Zapotiltic (23 km NE), Tamazula de Gordian (42 km NE), Valle de Juárez (85 km NE), Mazamitla (78 km NE), and Tonila (150 km NE). An explosion on 8 January generated an ash plume that rose 2 km and caused ashfall in Tuxpan, Tonila, and Zapotiltic. Another explosion on 11 January generated an ash plume that rose 1 km and caused ashfall in Tuxpan. An ash plume rose 500 m on 12 January and drifted ENE.
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, Elevation 3330 m
INGV reported that at night during 6-7 January the frequency of Strombolian explosions at Etna's Voragine Crater decreased; however, some of the explosions ejected incandescent pyroclastic material outside of the crater and onto the W and SW flanks. On 7 January many of the small explosions generated brown ashplumes that rose a few hundred meters above Etna's summit and quickly dissipated. Strombolian activity increased on 8 January, possibly from two vents within the crater. Pyroclastic material continued to be ejected out of the crater. Early on 9 January Strombolian activity again decreased and gave way to ash emissions that rose several hundred meters. Ash emissions continued the next morning, decreased, and had almost completely ceased by late morning. Ash emissions resumed in the afternoon and were sometimes accompanied by Strombolian explosions. Ash emissions on 13 January were continuous in the morning but then decreased in frequency by the afternoon.
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.
Hunga Tonga-Hunga Ha'apai, Tonga Islands
20.57°S, 175.38°W, Elevation 149 m
Based on a pilot observation, the Wellington VAAC reported that a dark ash plume from Hunga Tonga-Hunga Ha'apai rose to an altitude of 4.9 km (16,000 ft)a.s.l. on 12 January.
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.
Klyuchevskoy, Central Kamchatka (Russia)
56.056°N, 160.642°E, Elevation 4754 m
KVERT reported that a Strombolian eruption began at Klyuchevskoy on 1 January; bombs were ejected 300-400 m above the crater. On 10 January strong gas-and-steam emissions containing ash were recorded by the webcam. Video images also indicated a possible lava flow on the S flank. The Aviation Color Codewas raised to Orange. Strombolian and Vulcanian activity continued during 11-12 January, and explosions generated ash plumes that rose 5-7 km (16,400-23,000 ft) a.s.l. Satellite images on 11 January showed a 12.5-km-wide, 36.8-km-long ash plume drifting at an altitude of 5 km (16,400 ft) a.s.l. On 12 January an ash plume rose to an altitude of 5.5 km (18,000 ft) a.s.l. and drifted 35 km.
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.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Elevation 1117 m
JMA reported that four explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 5-9 January. Incandescence from the crater was visible at night during 7-8 January. Inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAACreported that during 7-8, 10, and 12-13 January plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE, SW, and NW. On 8 and 10 January pilots observed ash plumes that rose to altitudes of 1.5 km (10,000 ft) a.s.l. 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, 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 5-9 January. On 5 and 7 January incandescent material was sometimes ejected onto the crater rim. On 7 January plumes rose 1 km above the crater. 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, Elevation 2009 m
During 7-13 January, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure. The lava field expanded the N and NE margins. Seismicity remained strong and local air pollution from gas emissions persisted. GPS measurements showed that subsidence continued. The lava field covered 84.1 square kilometers on 10 January.
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, Elevation 724 m
SVERT reported that steam-and-gas emissions detected in satellite images rose 3 km above Chirinkotan and drifted SE on 5 January. A thermal anomaly was visible during 8 and 10-11 January. Cloud cover obscured views on the other days during 6-12 January. 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.
Fogo, Cape Verde
14.95°N, 24.35°W, Elevation 2829 m
The Observatório Vulcanológico de Cabo Verde (OVCV) reported that on 8 January the eruption at Fogo decreased in intensity; a small light-colored gas plume rose at most 100 m from the craters. Some explosions, following banging noises, were felt in areas 1 km away. Periodic explosions continued the next day and at 1530 a dark gas-and-ash plume rose 1.2 km and drifted SE. On 10 January light-colored, dense plumes rose at 800-1,200 m. Explosions on 11 January produced light-colored gas plumes that rose as high as1.5 km. On 12 January gas-and-ash plumes rose 800-1,000 m. In the afternoon a strong explosion was followed by smaller explosions and accompanying crashing noises that lasted for 2 hours. A very dense and dark-gray ash plume rose 2 km and drifted E, and was observed by people in S Philip and other parts of the island. At 1900 tephra was ejected 50 m above the crater. The lava-flow fronts to the N and S of Ilhéu de Losna were stagnant, while a few outbreaks were observed in Portela and Bangaeira.
Geologic summary: The island of Fogo consists of a single massive stratovolcano that is the most prominent of the Cape Verde Islands. The roughly circular 25-km-wide island is truncated by a large 9-km-wide caldera that is breached to the east and has a headwall 1 km high. The caldera is located asymmetrically NE of the center of the island and was formed as a result of massive lateral collapse of the ancestral Monte Armarelo edifice. A very youthful steep-sided central cone, Pico, rises more than 1 km above the caldera floor to about 100 m above the caldera rim, forming the 2829 m high point of the island. Pico, which is capped by a 500-m-wide, 150-m-deep summit crater, was apparently in almost continuous activity from the time of Portuguese settlement in 1500 CE until around 1760. Later historical lava flows, some from vents on the caldera floor, reached the eastern coast below the breached caldera.
14.473°N, 90.88°W, Elevation 3763 m
During 8-13 January INSIVUMEH reported that activity at Fuego continued at a high rate; explosions generated ash plumes that rose 550-950 m above the crater and drifted 10-15 km W and SW. Incandescent blocks traveled mainly down the Ceniza (SSW), Santa Teresa (W), and Las Lajas (SE) drainages and reached vegetated areas, generating small fires. Ashfall was reported in Panimache I and II (8 km SW), Santa Sofía (12 km SW), and areas in the municipality of San Pedro Yepocapa (8 km NW). During 10-13 January explosions ejected incandescent tephra 100-200 m above the crater causing avalanches in the Taniluya (SSW), Ceniza, and Trinidad (S) drainages.
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.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Elevation 1222 m
During 7-13 January HVO reported that Kilauea’s 27 June NE-trending lava flow continued to be active with breakout lava flows upslope of the leading front. On 13 January scientists conducted an overflight of the flow field and observed scattered breakouts along the distal part of the flow between 0.5 and 1 km upslope of the stalled flow front; a narrow lobe that had been advancing NNE was 700 m upslope of the stalled front. Additional breakouts were scattered from 1.7 to 3 km upslope of the flow tip and near the crack system.
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 ventcontinued to deposit variable amounts tephra onto nearby areas; smaller particles may have been dropped several kilometers away.
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.
Kuchinoerabujima, Ryukyu Islands (Japan)
30.443°N, 130.217°E, Elevation 657 m
JMA reported that no eruptions occurred from Kuchinoerabujima during 5-9 January, although the level of activity remained elevated. White plumes rose 500 m above the crater. Low-level seismicity continued and tremor was absent. The Alert Level remained at 3 (on a scale of 1-5).
Geologic summary: A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyus, 15 km west of Yakushima. Furutake, Shintake, and Noike were erupted from south to north, respectively, to form a composite cone that is parallel to the trend of the Ryukyu Islands. The highest peak, Furutake, reaches only 657 m above sea level. The youngest cone, 640-m-high Shintake, was formed after the NW side of Furutake was breached by an explosion. All historical eruptions have occurred from Shintake, although a lava flow from the S flank of Furutake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shintake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.
Nevado del Ruiz, Colombia
4.895°N, 75.322°W, Elevation 5321 m
According to a news article, increased ash emissions at Nevado del Ruiz prompted the closure of the La Nubia airport on 7 January.
Geologic summary: Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers >200 sq km. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the summit caldera of an older Ruiz volcano. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone is located on the SW flank, and may also have been active in historical time. Steep headwalls of massive landslides cut the flanks of Nevado del Ruiz. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America's deadliest eruption.
19.023°N, 98.622°W, Elevation 5426 m
CENAPRED reported that during 7-10 and 13 January seismicity at Popocatépetl indicated continuing emissions of water vapor and gas, which occasionally contained ash; steam-and-gas plumes were visible during 11-12 January. Cloud cover sometimes prevented views of the crater. Incandescence from the crater was visible nightly. Small explosions on 8 January at 1959 and on 9 January at 0149 produced ash plumes that rose 500 and 800 m, respectively. Three ash plumes recorded during 9-10 January rose 500-800 m and drifted E. An explosion on 12 January generated an ash plume that rose 800 m and drifted NE. The Alert Level remained at Yellow, Phase Two.
Geologic summary: Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5426 m 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major plinian eruptions, the most recent of which took place about 800 CE, have occurred from Popocatépetl since the mid Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since precolumbian time.
Santa Maria, Guatemala
14.756°N, 91.552°W, Elevation 3772 m
INSIVUMEH reported that an explosion from Caliente cone, part of Santa María's Santiaguito lava-dome complex, generated an ash plume that rose 600 m and drifted SW, causing ashfall in Monte Claro (S) and the Palajunoj area. On 11 January the lava-flow front was incandescent and produced avalanches that descended the flank. An explosion on 13 January generated an ash plume that rose 700 m and drifted SW.
Geologic summary: Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank and was formed during a catastrophic eruption in 1902. The renowned plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Elevation 3283 m
KVERT reported that during 2-9 January lava-dome extrusion onto Sheveluch’s N flank was accompanied by incandescence, hot avalanches, and fumarolicactivity. A strong explosion on 7 January generated an ash plume that rose to altitudes of 8-9 km (26,200-29,500 ft) a.s.l. A small pyroclastic flow descended the SE flank of the dome. Satellite images detected an ash plume drifting 350 km NW on 7 January, and a thermal anomaly over the dome during 7-8 January. TheAviation 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 seismicity at Shishaldin continued to be slightly elevated over background levels during 7-13 January. Nothing significant was observed in clear-to-partly cloudy satellite and web camera images. In a report from 9 January AVO noted that a small number of air-pressure waves from minor explosions within the summit crater were detected in seismic data intermittently during the previous week; there was no evidence of ash emissions outside of the crater. TheAviation 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, Elevation 2460 m
Based on satellite images, weather models, and ground observations, the Darwin VAAC reported an eruption from Sinabung on 10 January with an ash plume that rose to an altitude of 4 km (13,000 ft) a.s.l. Ashfall was reported in nearby areas at night on 11 January. During 12-13 January ash plumes rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted E.
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.
Sinarka, Shiashkotan Island (Russia)
48.875°N, 154.175°E, Elevation 934 m
SVERT reported that steam-and-gas emissions detected in satellite images rose 3 km above Sinarka and drifted SE on 5 January. Cloud cover obscured views on the other days during 6-12 January. The Aviation Color Code remained at Yellow.
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).
Zhupanovsky, Eastern Kamchatka (Russia)
53.589°N, 159.15°E, Elevation 2899 m
KVERT reported that a moderate eruption at Zhupanovsky continued during 2-9 January. Satellite images detected ash plumes drifting 50 km E on 6 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.