New activity/unrest was reported for 10 volcanoes from December 10 – December 16, 2014. Ongoing activity was observed at 13 volcanoes.
New activity/unrest: Asosan, Kyushu (Japan) | Chirinkotan, Kuril Islands (Russia) | Fogo, Cape Verde | Kusatsu-Shiranesan, Honshu (Japan) | Lopevi, Vanuatu | Moyorodake [Medvezhia], Iturup (Etorofu) Island (Japan/Russia) | Nevado del Ruiz, Colombia | Sinarka, Shiashkotan Island (Russia) | Villarrica, Chile | Zhupanovsky, Eastern Kamchatka (Russia)
Ongoing activity: Aira, Kyushu (Japan) | Bardarbunga, Iceland | Chirpoi, Kuril Islands (Russia) | Fuego, Guatemala | Kilauea, Hawaiian Islands (USA) | Kuchinoerabujima, Ryukyu Islands (Japan) | Mayon, Luzon (Philippines) | Ontakesan, Honshu (Japan) | Popocatepetl, Mexico | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Sinabung, Indonesia | Suwanosejima, Ryukyu Islands (Japan)
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 continued during 8-12 December; inclement weather often prevented observations of the crater. A webcam recorded tephra being carried by high winds and deposited in an area 1 km W. During a field survey on 10 December volcanologists observed 20-cm-wide blocks near the crater and 5-10-cm-wide blocks within 1.2 km SW of the crater. Plumes rose 600 m above the crater and incandescent material was sometimes ejected onto the crater rim. During 12-15 December the plume rose 1 km above the crater rim. Ashfall was reported E in Hanoi Aso (Kumamoto Region). Incandescent material was occasionally ejected onto the crater rim. 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 a thermal anomaly over Chirinkotan was detecetd in satellite images during 10-11 and 13-14 December. Cloud cover obscured views on the other days during 8-15 December. 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, Summit elev. 2829 m
According to news articles the rate of lava output from Fogo's Pico cone inside the Cha Caldera had decreased on 9 December and remained low through 14 December. Gas and ash emissions also decreased and were almost absent by 14 December. Even though output was low, the remaining buildings in the town of Bangaeira were overtaken by lava.
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.
Kusatsu-Shiranesan, Honshu (Japan)
36.618°N, 138.528°E, Summit elev. 2165 m
During 5-12 December JMA maintained Alert Level 2 for Kusatsu-Shiranesan due to continued unrest. GPS measurements indicated inflation, although thermal anomalies had been absent since July. Volcanic earthquakes continued at a low level and tremor was absent.
Geologic summary: The summit of Kusatsu-Shiranesan volcano, located immediately north of Asama volcano, consists of a series of overlapping pyroclastic cones and three crater lakes. The andesitic-to-dacitic volcano was formed in three eruptive stages beginning in the early to mid Pleistocene. The Pleistocene Oshi pyroclastic flow produced extensive welded tuffs and non-welded pumice that covers much of the east, south and SW flanks. The latest eruptive stage began about 14,000 years ago. All historical eruptions have consisted of phreatic explosions from the acidic crater lakes or their margins. Fumaroles and hot springs that dot the flanks have strongly acidified many rivers draining from the volcano. The crater was the site of active sulfur mining for many years during the 19th and 20th centuries.
16.507°S, 168.346°E, Summit elev. 1413 m
On 15 December the Vanuatu Geohazards Observatory reported that, based on observations and analyses in early December, activity at Lopevi had increased dramatically over a short time period. The Alert Level was raised to 1 (on a scale of 0-4), and access to the island was prohibited.
Geologic summary: The small 7-km-wide conical island of Lopevi, known locally as Vanei Vollohulu, is one of Vanuatu's most active volcanoes. A small summit crater containing a cinder cone is breached to the NW and tops an older cone that is rimmed by the remnant of a larger crater. The basaltic-to-andesitic volcano has been active during historical time at both summit and flank vents, primarily along a NW-SE-trending fissure that cuts across the island, producing moderate explosive eruptions and lava flows that reached the coast. Historical eruptions at the 1413-m-high volcano date back to the mid-19th century. The island was evacuated following major eruptions in 1939 and 1960. The latter eruption, from a NW-flank fissure vent, produced a pyroclastic flow that swept to the sea and a lava flow that formed a new peninsula on the western coast.
Moyorodake [Medvezhia], Iturup (Etorofu) Island (Japan/Russia)
45.389°N, 148.838°E, Summit elev. 1124 m
On 12 December SVERT reported that activity at Kudriavy, a stratovolcano of the Medvezhia volcanic complex, had not increased since 1 December. The Aviation Color Code was lowered to Green.
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.
Nevado del Ruiz, Colombia
4.895°N, 75.322°W, Summit elev. 5321 m
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico and Sismológico de Manizales reported that on 15 December at 0738 seismic signals indicating ash emissions were detected, and then confirmed, by a local webcam and residents. Based on a pilot observation, the Washington VAAC noted that an ash plume drifted almost 20 km S that same day. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").
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.
Sinarka, Shiashkotan Island (Russia)
48.875°N, 154.175°E, Summit elev. 934 m
SVERT reported that on 8 December satellite images of Sinarka showed diffuse steam-and-gas emissions. Cloud cover obscured views on the other days during 9-15 December. The Aviation Color Code was raised to 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).
39.42°S, 71.93°W, Summit elev. 2847 m
According to Projecto Observación Visual Volcán Villarrica (POVI), satellite images of Villarrica acquired on 10 and 26 November and 3 December revealed a progressively more intense thermal anomaly. Photographs on 9 December showed particulates suspended above the crater rim, and the next day a thin veneer of ash covered the NW edge of the crater rim. Detonations from the crater were heard during 10-12 December. On 13 December observers noted that the intense blasts of gas from the previous few days had removed some ash deposits from the inner crater wall leaving lighter colored streaks.
Geologic summary: Glacier-clad Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot Villarrica's flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano have been produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Historical eruptions, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 sq km of the volcano, and lahars have damaged towns on its flanks.
Zhupanovsky, Eastern Kamchatka (Russia)
53.589°N, 159.15°E, Summit elev. 2899 m
KVERT reported that an eruption at Zhupanovsky continued during 5-12 December. Satellite images detected a thermal anomaly on 9 December; the volcano was either quiet or obscured by clouds 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 four explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,800 m during 8-12 December. Incandescence from the crater was visible at night during 11-12 December. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported plumes during 11, 13, and 15-16 December that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted SE and NE. On 11 December a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted NE.
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 10-16 December, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure. A decreased rate of subsidence of the Bárdarbunga Caldera continued. The lava field covered just over 78.6 square kilometers on 15 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 during 8-14 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.
14.473°N, 90.88°W, Summit elev. 3763 m
In a special bulletin issued on 10 December, INSIVUMEH reported that during the previous few weeks activity at Fuego had remained high, characterized by ash emissions, frequent powerful explosions, and rumbling. On 10 December activity changed, with explosions being accompanied by lava fountains that rose 100-150 m above the crater. During 11-16 December explosions generated ash plumes that rose 650-850 m and drifted 15 km W, SW, S, and SE. Avalanches from lava flows descended drainages. Ashfall was reported in areas near the observatory, and in Morelia (9 km SW) and Panimaché (8 km SW). Incandescent material was ejected 100 m above the crater and explosions sometimes generated shock waves.
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 10-16 December HVO reported that Kilauea’s 27 June NE-trending lava flow continued to be active. A narrow lobe of lava that had broken away from the W edge of the flow field below the crack system advanced at rates of several hundred meters per day; by 16 December the front was about 1.6 km above the intersection of Pahoa Village Road and Highway 130, near the Pahoa Marketplace.
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; 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 8-12 December, although the level of activity remained elevated. White plumes rose 400 m above the crater. Low-level seismicity continued and tremor was absent. Sulfur dioxide emissions increased on 9 December; measurements indicated a rate of 1,700 tons per day. 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.
Mayon, Luzon (Philippines)
13.257°N, 123.685°E, Summit elev. 2462 m
PHIVOLCS reported that during 9-16 December white plumes were occasionally observed rising from Mayon's crater and drifted WNW and WSW, sometimes downslope. Three volcanic earthquakes were recorded on 9 December and one was recorded on 11 December. Alert Level remained at 3 (on a 0-5 scale). PHIVOLCS reminded residents of the 6-km-radius Permanent Danger Zone (PDZ) around the volcano and the 7-km Extended Danger Zone (EDZ) on the SE flank.
Geologic summary: Beautifully symmetrical Mayon volcano, which rises to 2462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions at this basaltic-andesitic volcano date back to 1616 and range from strombolian to basaltic plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1200 people and devastated several towns.
Ontakesan, Honshu (Japan)
35.893°N, 137.48°E, Summit elev. 3067 m
JMA reported that cloud cover mostly prevented visual observations of Ontakesan during 10-16 December; white plumes rose 50 m above the crater rim and drifted SW on 10 December. Seismicity remained low. The Alert Level remained at 3 (on a scale of 1-5).
Geologic summary: The massive Ontakesan stratovolcano, the second highest volcano in Japan, lies at the southern end of the Northern Japan Alps. Ascending this volcano is one of the major objects of religious pilgrimage in central Japan. It is constructed within a largely buried 4 x 5 km caldera and occupies the southern end of the Norikura volcanic zone, which extends northward to Yakedake volcano. The older volcanic complex consisted of at least four major stratovolcanoes constructed from about 680,000 to about 420,000 years ago, after which Ontakesan was inactive for more than 300,000 years. The broad, elongated summit of the younger edifice is cut by a series of small explosion craters along a NNE-trending line. Several phreatic eruptions post-date the roughly 7300-year-old Akahoya tephra from Kikai caldera. The first historical eruption took place in 1979 from fissures near the summit. A non-eruptive landslide in 1984 produced a debris avalanche and lahar that swept down valleys south and east of the volcano. Very minor phreatic activity caused a dusting of ash near the summit in 1991 and 2007. A significant phreatic explosion in September 2014, when a large number of hikers were at or near the summit, resulted in many fatalities.
19.023°N, 98.622°W, Summit elev. 5426 m
CENAPRED reported that during 10-16 December seismicity at Popocatépetl indicated continuing emissions of water vapor, gas, and ash. Incandescence from the crater was visible each night. Explosions were detected at 0052 and 0132 on 10 December. Multiple explosions on 16 December generated ash plumes that rose 1 km. An explosion at 0259 ejected incandescent material onto the NE flank, less than 200 m from the crater. 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.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m
KVERT reported that during 5-12 December lava-dome extrusion onto Sheveluch’s N flank was accompanied by incandescence, hot avalanches, and fumarolic activity. Two strong explosions on 5 and 11 December generated ash plumes that rose to altitudes of 8-9 km (26,200-29,500 ft) a.s.l. and drifted 200 km ENE on 5 December and 364 km on 11 December. Satellite images detected a thermal anomaly over the dome during 5 and 9-11 December; 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 seismicity at Shishaldin continued to be elevated during 10-16 December. Nothing significant was observed in partly-to-mostly cloudy satellite and web camera images. 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 on 10 December an ash plume from Sinabung rose to an altitude of 4.9 km (16,000 ft) a.s.l. and drifted SW. The notice stated that the eruption was more significant and higher than the intermittent pyroclastic flows observed during the previous week. Eruptions during 11-16 December produced ash plumes that rose to altitudes of 4.3-6.1 km (14,000-20,000 ft) a.s.l. and drifted at most 30 km N, NW, and W.
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.
Suwanosejima, Ryukyu Islands (Japan)
29.638°N, 129.714°E, Summit elev. 796 m
The Tokyo VAAC reported that on 14 December an explosion at Suwanosejima produced a plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SE.
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.
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