New unrest has been noticed around 7 volcanoes, ongoing activity was reported for 12 volcanoes. This report covers active volcanoes in the world recorded from September 5 – September 11 2012 based on Smithsonian/USGS criteria.
The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program. Updated by 23:00 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth’s volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the “Criteria and Disclaimers” section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
New activity/unrest: | Apoyeque, Nicaragua | Grozny Group, Iturup Island | Krakatau, Indonesia | Little Sitkin, Aleutian Islands | San Cristóbal, Nicaragua | Soufrière Hills, Montserrat | Tangkubanparahu, Western Java (Indonesia) .
Ongoing activity: | Batu Tara, Komba Island (Indonesia) | Cleveland, Chuginadak Island | Fuego, Guatemala | Gamkonora, Halmahera | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) |Machín, Colombia | Nevado del Ruiz, Colombia | Paluweh, Lesser Sunda Islands (Indonesia) | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Sirung, Pantar Island (Indonesia).
12.242°N, 86.342°W; summit elev. 518 m
INETER reported that a seismic swarm near Apoyeque started at 1627 on 6 September in an area between the volcano and Managua (less than 10 km SW). At the time of the report, almost four hours after the start of the event, 17 earthquakes had been detected; three events were M 2.3-3.7, at depths ranging from 2.8 to 6 km. No earthquakes were recorded on 9 September.
Geologic summary: The Apoyeque volcanic complex occupies the broad Chiltepe Peninsula, which extends into south-central Lake Managua. The peninsula is part of the Chiltepe pyroclastic shield volcano, one of three large ignimbrite shields on the Nicaraguan volcanic front. A 2.8-km wide, 400-m-deep, lake-filled caldera whose floor lies near sea level truncates the low Apoyeque volcano, which rises only about 500 m above the lake shore. The caldera was the source of a thick mantle of dacitic pumice that blankets the surrounding area. The 2.5 x 3 km wide lake-filled Xiloá (Jiloá) maar, is located immediately SE of Apoyeque. The Talpetatl lava dome was constructed between Laguna Xiloá and Lake Managua. Pumiceous pyroclastic flows from Laguna Xiloá were erupted about 6100 years ago and overlie deposits of comparable age from the Masaya plinian eruption.
GROZNY GROUP, Iturup Island
45.026°N, 147.922°E; summit elev. 1211 m
Based on visual observations and analyses of satellite imagery, SVERT reported that during 4-10 September fumarolic activity at Grozny Group increased. The Aviation Color Code remained at Yellow.
Geologic summary: The Grozny volcano group in central Iturup Island contains the complex volcanoes of Ivan Grozny and Tebenkov. The former has a 3-3.5 km diameter caldera that is open to the south, where the large, 1158-m-high andesitic Grozny extrusion dome (also known as Etorofu-Yake-yama) was emplaced. Several other lava domes of Holocene age were constructed to the NE; extrusion of these domes has constricted a former lake in the northern side of the caldera to an extremely sinuous shoreline. The forested andesitic Tebenkov volcano, also known as Odamoi-san, lies immediately to the NE of the Grozny dome complex. The large Machekh crater, which displays strong fumarolic activity, lies immediately south of Tebenkov. Historical eruptions, the first of which took place in 1968, have been restricted to Ivan Grozny.
6.102°S, 105.423°E; summit elev. 813 m
According to NASA’s Earth Observatory, a satellite image of Krakatau acquired on 4 September showed freshlava flows descending the SE flank of Anak Krakatau, extending the shoreline by about 100 m.
Geologic summary:Renowned Krakatau volcano lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, resulted in a 7-km-wide caldera. Remnants of this volcano formed Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. The post-collapse cone of Anak Krakatau (Child of Krakatau), constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan, has been the site of frequent eruptions since 1927.
LITTLE SITKIN, Aleutian Islands
51.95°N, 178.543°E; summit elev. 1174 m
AVO reported that during 5-11 September seismic activity at Little Sitkin was much lower than the peak of activity during 29-30 August, but continued to remain elevated. Satellite views were obscured by clouds during 5 and 8-11 September. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.
Geologic summary: Diamond-shaped Little Sitkin Island is bounded by steep cliffs on the east, north, and NE sides. Little Sitkin volcano contains two nested calderas. The older, nearly circular Pleistocene caldera is 4.8 km wide, may have once contained a caldera lake, and was partially filled by a younger cone formed mostly of andesitic and dacitic lava flows. The elliptical younger caldera is 2.7 x 4 km wide; it lies within the eastern part of the older caldera and shares its eastern and southern rim. The younger caldera partially destroyed the lava cone within the first caldera and is of possible early Holocene age. Young-looking dacitic lava flows, erupted in 1828 (Kay, in Wood and Kienle 1990), issued from the central cone within the younger caldera and from a vent on the west flank outside the older caldera. Fumarolic areas are found near the western coast, along the NW margin of the older caldera, and from the summit crater down the southern flank for a 1 km distance.
SAN CRISTOBAL, Nicaragua
12.702°N, 87.004°W; summit elev. 1745 m
INETER reported that on 8 September three explosions from San Cristóbal produced ash-and-gas plumes that rose 1.5 km above the crater and drifted 9 km/hr NW. Ashfall was reported in El Viejo (18 km WSW), El Chonco, and Ranchería. Sporadic explosions later that day generated ash plumes that rose 1.5-5 km and drifted 50 km WNW. Ash fell in an area covering 2,438 square kilometers, including the communities of El Viejo, La Grecia, La Joya, Santa Catalina, El Piloto, Las Banderas, Las Rojas, Carlos Fonseca, Jiquilillo, Mechapa, and Cosiguina. Ashfall was 5 cm thick in areas near the crater and up to 3 mm thick in more distant places. Sulfur dioxide emissions were 3,221 tons per day, well above the normal range of 550 to 700 tons per day. A resident near the volcano reported landslides and falling rocks in the N part of the crater. Incandescent rocks fell in areas NW, causing burns on livestock. Residents in Versalles Arriba, near the crater, reported seeing a fissure. According to a news article, officials evacuated about 3,000 people. SINAPRED reported that airplanes were diverted around San Cristóbal to other airways.
Geologic summary: The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1,745-m-high youngest cone, San Cristóbal itself (also known as El Viejo), is Nicaragua’s highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km to the west of San Cristóbal; it and the eroded Moyotepe volcano, 4 km to the NE of San Cristóbal, are of Pleistocene age. Volcán Casita contains an elongated summit crater and lies immediately E of San Cristóbal; Casita was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristóbal complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes.
SOUFRIERE HILLS, Montserrat
16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 31 August-7 September activity at the Soufrière Hills lava dome was at a low level, although seismicity remained slightly elevated. Clear views of parts of the dome showed very little change, apart from some modification to the steep eastern face from the formation of the pyroclastic flow on 29 August. The Hazard Level remained at 2 (on a scale of 1-5).
Geologic summary: The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English’s Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.
TANGKUBANPARAHU, Western Java (Indonesia)
6.77°S, 107.60°E; summit elev. 2084 m
CVGHM reported that seismicity at Tangkubanparahu had increased significantly on 13 August, then again on 23 August; seismicity fluctuated and remained elevated through 6 September. Earthquakes were located 0.5-4 km beneath Ratu Crater and in an area W at depths of 4-12 km. Soil temperatures at Ratu Crater showed an increasing trend on 31 August, but had gradually declined by 5 September. Sulfur dioxide gas emissions were high in an area NW of the crater, causing CVGHM to remind visitors not to approach the crater within a 1.5-km radius. Based on seismicity, visual observations, gas measurements, and crater lake water temperatures through 7 September, the Alert Level remained at 2 (on a scale of 1-4).
Geologic summary: Tangkubanparahu is a broad shield-like stratovolcano overlooking Indonesia’s former capital city of Bandung that was constructed within the 6 x 8 km Pleistocene Sunda caldera. The volcano’s low profile is the subject of legends referring to the mountain of the “upturned boat.” The rim of Sunda caldera forms a prominent ridge on the western side; elsewhere the caldera rim is largely buried by deposits of Tangkubanparahu volcano. The dominantly small phreatic historical eruptions recorded since the 19th century have originated from several nested craters within an elliptical 1 x 1.5 km summit depression. Tangkubanparahu last erupted in September 1983, when ash rose up to 150 m above the rim of Kawah Ratu.
BATU TARA, Komba Island (Indonesia)
7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 5-11 August ash plumes from Batu Tara rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 55-75 km W, WNW, and NW.
Geologic summary: The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy’s Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow.
CLEVELAND, Chuginadak Island
52.825°N, 169.944°W; summit elev. 1730 m
On 5 September, AVO reported that satellite views of Cleveland showed no evidence of further eruptive activity since the last explosion on 20 August. Fresh lava within the summit crater was last detected in images in early May. The Volcano Alert Level was lowered to Advisory and the Aviation Color Code was lowered to Yellow.
Geologic summary: Symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.
14.473°N, 90.880°W; summit elev. 3763 m
In a special bulletin on 4 September at 1700, INSIVUMEH reported that the eruption from Fuego that began 32 hours earlier had ended. During 6-11 September fumarolic plumes rose 100-150 m above the crater and drifted W and NW. Weak explosions generated ash plumes that rose 300-400 m above the crater and drifted W and NW. During 8-9 September incandescent tephra was ejected to a height of 100 m and caused avalanches in the Taniluyá and the Ceniza (SSW) drainages. A 10-20-m-wide lahar traveled SE down the Las Lajas drainage on 9 September, carrying tree trunks and blocks 1.5 m in diameter. During 10-11 September a lava flow traveled 100 m down the Taniluyá drainage.
Geologic summary: Volcán Fuego, one of Central America’s most active volcanoes, is one of three largestratovolcanoes overlooking Guatemala’s former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historicaleruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua.
1.38°N, 127.53°E; summit elev. 1635 m
CVGHM reported that on 7 September the Alert Level for Gamkonora was lowered from 3 to 2 (on a scale of 1-4).
Geologic summary: The shifting of eruption centers on Gamkonora, at 1635 m the highest peak of Halmahera, has produced an elongated series of summit craters along a N-S trending rift. Youthful-looking lava flows originate near the cones of Gunung Alon and Popolojo, south of Gamkonora. Since its first recorded eruption in the 16th century, Gamkonora has typically produced small-to-moderate explosive eruptions. Its largest historicaleruption, in 1673, was accompanied by tsunamis that inundated villages.
KARYMSKY, Eastern Kamchatka (Russia)
54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported weak-to-moderate seismic activity from Karymsky during 31 August-7 September. Seismic data indicated that ash plumes possibly rose to an altitude of 2.5 km (8,200 ft) a.s.l. Satellite imagery showed a thermal anomaly on the volcano on 31 August and 1 September. The Aviation Color Code remained at Orange.
Geologic summary: Karymsky, the most active volcano of Kamchatka’s eastern volcanic zone, is a symmetricalstratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996.
KILAUEA, Hawaii (USA)
19.421°N, 155.287°W; summit elev. 1222 m
During 5-11 September HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kilauea’s Halema’uma’u Crater. The gas plume from the vent continued to deposit variable amounts ofspatter and Pele’s hair onto nearby areas.
On 4 September HVO geologists observed the Pu’u ‘O’o Crater floor and noted lava ponds in the E and S pits, with the N pit being fully crusted over. During 5-11 September glow emanated from the E and S pit craters; lava in the N pit was crusted, but was periodically incandescent on the W edge. A collapse in the roof of the lava tube at the base of the SE flank of Pu’u ‘O’o also continued to glow. Lava flows were active above and at the top of the pali. On 11 September a geologist confirmed that lava flows above the pali had advanced to the top of the abandoned Royal Gardens subdivision.
Geologic summary: Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world’s most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 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.
4.48°N, 75.392°W; summit elev. 2650+ m
According to INGEOMINAS, Observatory Vulcanológico and Sismológico de Manizales reported that at 0732 on 9 September a M 3.6 volcano-tectonic earthquake occurred below the main lava dome at Cerro Machín at a depth of 3.2 km, and was felt by nearby residents. The Alert Level remained at III (Yellow; “changes in the behavior of volcanic activity”).
Geologic summary: The small Cerro Machín stratovolcano lies at the southern end of the Ruiz-Tolima massif about 20 km WNW of the city of Ibagué. A 3-km-wide caldera is breached to the S and contains three forestedlava domes. Voluminous pyroclastic flows traveled up to 40 km from the volcano during eruptions in the mid-to-late Holocene perhaps associated with formation of the caldera. Late-Holocene eruptions produced block-and-ash flows that traveled through the breach in the caldera rim to the W and S. The latest known eruption of Volcán Cerro Machín took place about 800 years ago.
NEVADO DEL RUIZ, Colombia
4.895°N, 75.322°W; summit elev. 5321 m
According to INGEOMINAS, on 5 September the Observatorio Vulcanológico and Sismológico de Manizales reported that seismicity at Nevado del Ruiz significantly decreased, both in the number and magnitude of the earthquakes. Field measurements and analysis of satellite imagery continued to show a significant amount of sulfur dioxide in the atmosphere. A steam-and-gas plume rose 400 m and drifted W. Later that day, INGEOMINAS decreased the Alert Level to 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. 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.
PALUWEH, Lesser Sunda Islands (Indonesia)
8.32°S, 121.708°E; summit elev. 875 m
CVGHM reported that on 7 September the Alert Level for Paluweh was lowered from 2 to 1 (on a scale of 1-4).
Geologic Summary. Paluweh volcano, also known as Rokatenda, forms the 8-km-wide island of Paluweh N of the volcanic arc that cuts across Flores Island. Although the volcano rises about 3,000 m above the sea floor, its summit reaches only 875 m above sea level. The broad irregular summit region contains overlapping craters up to 900 m wide and several lava domes. Several flank vents occur along a NW-trending fissure. The largest historical eruption of Paluweh occurred in 1928, when a strong explosive eruption was accompanied by landslide-induced tsunamis and lava-dome emplacement.
31.585°N, 130.657°E; summit elev. 1117 m
JMA reported that during 3-7 September six explosive eruptions from Sakura-jima’s Showa Crater ejected tephra as far as 1.3 km from the crater. Incandescence from the crater was observed at night. Based on information from JMA, the Tokyo VAAC reported that explosions during 6-11 September often produced plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. The plumes sometimes drifted N, NE, and SE. On 10 September a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted E.
Geologic Summary. Sakura-jima, one of Japan’s most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. 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.
SHIVELUCH, Central Kamchatka (Russia)
56.653°N, 161.360°E; summit elev. 3283 m
Based on visual observations and analyses of satellite data, KVERT reported that during 31 August-7 September a viscous lava flow continued to effuse on the NE flank of Shiveluch’s lava dome, and was accompanied by hot avalanches and fumarolic activity. Satellite imagery showed a thermal anomaly over the lava dome during 31 August and 4-5 September; cloud cover prevented observations on the other days. The Aviation Color Code remained at Orange.
Geologic summary: The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka’s largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocenewithin a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesiticvolcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
SIRUNG, Pantar Island (Indonesia)
8.508°S, 124.13°E; summit elev. 862 m
CVGHM reported that on 7 September the Alert Level for Sirung was lowered from 2 to 1 (on a scale of 1-4).
Geologic Summary. Sirung volcano is located at the NE end of a 14-km-long line of volcanic centers that form a peninsula at the southern end of Pantar Island. The low, 862-m-high volcano is truncated by a 2-km-wide caldera whose floor often contains one or more small lakes. Much of the volcano is constructed of basaltic lava flows, and the Gunung Sirung lava dome forms the high point on the caldera’s western rim. A number of phreatic eruptions have occurred from vents within the caldera during the 20th century.
Source: Global Volcanism Program
Featured image: San Cristobal eruption
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