New activity/unrest was observed at 7 volcanoes from November 26 - December 2, 2014. Ongoing activity was observed at 11 volcanoes.
New activity/unrest: Asosan, Kyushu (Japan) | Chirinkotan, Kuril Islands (Russia) | Fogo, Cape Verde | Heard, Kerguelen Plateau | Moyorodake [Medvezhia], Iturup (Etorofu) Island (Japan/Russia) | Sinarka, Shiashkotan Island (Russia) | Zhupanovsky, Eastern Kamchatka (Russia)
Ongoing activity: Aira, Kyushu (Japan) | Bardarbunga, Iceland | Chirpoi, Kuril Islands (Russia) | Colima, Mexico | Copahue, Central Chile-Argentina border | Fuego, Guatemala | Kilauea, Hawaiian Islands (USA) | Kuchinoerabujima, Ryukyu Islands (Japan) | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Sinabung, Indonesia
Asosan, Kyushu (Japan)
32.884°N, 131.104°E, Summit elev. 1592 m
JMA reported that on 25 November an eruption from Asosan’s Nakadake Crater occurred after increased tremor detected a few hours earlier. Ash plumes rose from the crater and produced ashfall to the E in Hanoi Aso (Kumamoto Region), Taketa (30 km NE, Oita Region), Gokase (25 km WSW, Miyazaki Region), and in Minamiaso (10 km SW, Kumamoto Region). Incandescence from the crater was recorded at night with webcams. On 26 November tephra was ejected 100 m above the crater rim and an ash plume rose 1 km. Tremor continued to be elevated. The eruption remained strong on 27 November, and ash plumes rose 1.5 km. During a field survey in an area S of Nakadake Crater volcanologists observed Strombolian activity in the crater, 7 cm of ash deposition, and fist-sized scoria. Ashfall was reported in a wide area to the W, mainly in Kumamoto (38 km WSW). According to a news article, flights in and out of Kumamoto airport were either cancelled or diverted. On 28 November ash plumes rose 1.5 km. The eruption continued through 30 November; ash plumes rose at most 1.5 km and incandescent material was ejected onto the crater rim. Inclement weather mostly prevented views of the crater during 1-2 December, but the small-scale eruption likely 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.
Chirinkotan, Kuril Islands (Russia)
48.98°N, 153.48°E, Summit elev. 724 m
SVERT reported that since 21 November a thermal anomaly and increased gas-and-steam emissions at Chirinkotan were detected in satellite images. A thermal anomaly was detected on 25 November, and a diffuse steam-and-gas plume drifted 40 km SE on 27 November. Steam-and-gas emissions were again observed on 28 and 30 November. The Aviation Color Code was raised to 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, Summit elev. 2829 m
According to news articles the eruption from Fogo's Pico cone inside the Cha Caldera continued during 26 November-2 December. In the morning of 30 November the eruption intensified; lava travelled at a rate of 20 m/hour and caused the closure of the only alternative route between the national park and Portela, the main town in the caldera. Authorities warned all residents in the caldera to evacuate. Lava destroyed almost 25 homes, a large area of agricultural land, the Parque Natural do Fogo museum, and other infrastructure. By 2 December there were two lava fronts. After about 24 hours of minimal advancement, the rate of advancement increased; lava overtook several more houses, a school, and a hotel.
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.
Heard, Kerguelen Plateau
53.106°S, 73.513°E, Summit elev. 2745 m
According to a NOAA National Environmental Satellite, Data, and Information Service (NESDIS) scientist, thermal anomalies seemingly on the E flank of Heard were detected in Visible Infrared Imaging Radiometer Suite (VIIRS) satellite images during 2-30 November. Dense cloud cover prevented views of the volcano during 1-2 December. MODIS (Moderate Resolution Imaging Spectroradiometer) images had detected thermal anomalies from September 2014 to 21 July 2014, and again on 16 November 2014, due to a persisting lava lake and possible lava flows.
Geologic summary: Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon volcano lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben volcano because of its extensive ice cover. The historically active Mawson Peak forms the island's 2745-m high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported in historical time at this isolated volcano, but observations are infrequent and additional activity may have occurred.
Moyorodake [Medvezhia], Iturup (Etorofu) Island (Japan/Russia)
45.389°N, 148.838°E, Summit elev. 1124 m
On 27 November SVERT reported that during the previous 10 days a thermal anomaly and strengthening steam-and-gas activity were detected over Kudriavy, a stratovolcano of the Medvezhia volcanic complex. The size and intensity of the thermal anomaly increased considerably on 27 November. The Aviation Color Code was raised to Yellow. Diffuse steam-and-gas emissions were observed on 29 November.
Geologic summary: The Moyorodake volcanic complex (also known as Medvezhia) occupies the NE end of Iturup (Etorofu) Island. Two overlapping calderas, 14 x 18 and 10 x 12 km in diameter, were formed during the Pleistocene. The caldera floor contains several lava domes, cinder cones and associated lava fields, and a small lake. Four small closely spaced stratovolcanoes were constructed along an E-W line on the eastern side of the complex. The easternmost and highest, Medvezhii, lies outside the western caldera, along the Pacific coast. Srednii, Tukap, and Kudriavy (Moyorodake) volcanoes lie immediately to the west. Historically active Moyorodake is younger than 2000 years; it and Tukap remain fumarolically active. The westernmost of the post-caldera cones, Menshoi Brat, is a large lava dome with flank scoria cones, one of which has produced a series of young lava flows up to 4.5 km long that reached Slavnoe Lake. Eruptions of Moyorodake have been documented since the 18th century, although lava flows from cinder cones on the flanks of Menshoi Brat were also probably erupted within the past few centuries.
Sinarka, Shiashkotan Island (Russia)
48.875°N, 154.175°E, Summit elev. 934 m
SVERT reported that on 27 November satellite images of Sinarka showed steam-and-gas emissions drifting 50 km SE. Cloud cover obscured views on the other days during 24 November-1 December. 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, Summit elev. 2899 m
KVERT reported that strong explosions at Zhupanovsky were detected at 0206 on 23 November and 1214 on 25 November. Ash plumes rose to altitudes of 7-8 km (23,000-26,200 ft) a.s.l. and drifted 350 km E on 22 November and SE during 25-27 November. Satellite images detected a thermal anomaly over the volcano on 22, 25, and 27 November; cloud cover prevented views of the volcano on the other days. 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.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m
JMA reported that periodic, small-scale explosions from Showa Crater at Aira Caldera’s Sakurajima were detected during 25-28 November. Weak incandescence from the crater was visible during 25-26 November. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 27-30 November plumes rose to altitudes of 1.5-4.9 km (5,000-16,000 ft) a.s.l. and drifted NE, E, and SE. An eruption on 2 December generated a plume that rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted SE.
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.
64.63°N, 17.53°W, Summit elev. 2009 m
During 26 November-2 December, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure. Based on a field report from 25 or 26 November the activity was characterized as pulsating; lava surged from the vent for 2-3 minutes, every 5-10 minutes, causing bulges in the upper parts of the lava channel. Measurements obtained during an overflight on 26 November indicated that the total amount of subsidence of the Bárdarbunga Caldera was about 50 m, with an estimated volume of 1.4 cubic kilometers. The rate of subsidence in the center of the caldera had decreased slowly compared to the first month of the eruption. Observers in Dyngjusandur, NE of the vent, photographed the plume at 1441 on 27 November and indicated that the top of the plume was 3.1 km above Dyngjusandur, and the base of the aerosol-laden lower part of the plume was about 1.4 km above the sand plain. A thermal image from 1 December showed several changes to the lava field: in just over 24 hours a new lava extrusion at the NE margin traveled 450 m; a new flow traveled N, just W of the lava lake; and a new flow was forming S of the lava lake, and then to the E of that flow. The lava field covered just over 75 square kilometers on 1 December.
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, Summit elev. 742 m
SVERT reported that satellite images over Snow, a volcano of Chirpoi, showed a thermal anomaly on 27 November. Cloud cover obscured views on other days during 25 November-1 December. 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, Summit elev. 3850 m
Based on satellite image analyses, the Washington VAAC reported that on 30 November an ash puff from Colima drifted NE. Later that day a puff of likely gas and ash drifted E at an altitude below 4.9 km (16,000 ft) a.s.l.
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.
Copahue, Central Chile-Argentina border
37.856°S, 71.183°W, Summit elev. 2953 m
The Buenos Aires VAAC reported that on 26 November diffuse steam-and-gas emissions from Copahue, recorded by the ODVAS webcam and satellite images, possibly contained a small amount of ash. The plume rose to altitudes of 3.4-3.7 km (11,000-12,000 ft) a.s.l. and drifted 65 km E. On 30 November a pilot observation and webcam views revealed a diffuse and continuous plume near the summit. During 1-2 December a diffuse plume was detected in satellite images while the webcam recorded continuous ash emissions.
Geologic summary: Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded at Copahue since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.
14.473°N, 90.88°W, Summit elev. 3763 m
INSIVUMEH reported that during 28-30 November explosions at Fuego produced ash plumes that rose at most 1.2 km above the crater and drifted as far as 25 km S, SW, and W. Shock waves from some of the explosions rattled structures near the volcano. Incandescent material was ejected 100-150 m above the crater duirng 29-30 November. Ashfall was reported in Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), and surrounding communities.
In a special bulletin issued on 1 December, INSIVUMEH reported that activity remained similar to the previous few days, characterized by periods of more frequent and intense explosions observed 6-8 times per hour. Dense gray ash plumes rose almost 1.3 km and drifted 20 km W and SW. Ash fell in Morelia, Santa Sofía, Panimaché, and Yepocapa. Some explosions were audible up to 30 km away. Shock waves vibrated structures on the S and SW flanks. Incandescent blocks descended multiple drainages. During 1-2 December explosions generated ash plumes that rose 850 m and drifted 15 km S and SW.
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, Summit elev. 1222 m
During 26 November-2 December HVO reported that Kilauea’s 27 June NE-trending lava flow continued to be active. During an overflight on 1 December volcanologists observed a narrow lava flow that had originated from the W edge of the flow field and traveled 2.8 km N, burning vegetation along its path. They noted that weak surface activity was present in three areas upslope: the W side of the flow field that had produced the new lava flow, the E edge of the crack system, and at a breakout 3.5 km upslope of Pu'u 'O'o. They also measured a cross-sectional area of the lava stream within a tube near Pu'u 'O'o and found a 25% reduction in area compared to the previous week. The result was consistent with less lava flowing through the tube due to the summit deflation, which has been ongoing since 29 November.
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 of tephra onto nearby areas; smaller particles may have been dropped several kilometers away. At Pu'u 'O'o Crater, glow emanated from several outgassing openings in the crater floor.
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, Summit elev. 657 m
JMA reported that no eruptions occurred from Kuchinoerabujima during 25-28 November although the level of activity remained elevated. White plumes rose 200 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.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m
KVERT reported that during 21-27 November lava-dome extrusion onto Sheveluch’s N flank was accompanied by incandescence, hot avalanches, and fumarolic activity. Strong explosions at 1021 on 23 November and 0328 on 26 November generated ash plumes that rose to altitudes of 8-9 km (26,200-29,500 ft) a.s.l and drifted 400 km NE and 200 km SE, respectively. Satellite images detected a thermal anomaly over the dome during 22-23 and 26-27 November; cloud cover prevented views of the volcano on the other days. 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 although seismicity at Shishaldin continued to be elevated, levels declined during 26 November-2 December. Elevated crater temperatures were detected in satellite images during periods of clear weather from 26 to 28 November. A low-level lava eruption was likely still occurring within the summit crater of the volcano. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.
Geologic summary: The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." A steady steam plume rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the west and NE sides at 1500-1800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century.
3.17°N, 98.392°E, Summit elev. 2460 m
Based on webcam views and weather models, the Darwin VAAC reported that during 2-3 December ash plumes from Sinabung rose to an altitude of 3 km (10,000 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.