New unrest has been noticed around 5 volcanoes, ongoing activity was reported for 8 volcanoes. This report covers active volcanoes in the world recorded from September 19 – September 25, 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: | Fuego, Guatemala | Little Sitkin, Aleutian Islands | Lokon-Empung, Sulawesi |Soputan, Sulawesi | Tangkubanparahu, Western Java (Indonesia)
Ongoing activity: | Batu Tara, Komba Island (Indonesia) | Galeras, Colombia | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Reventador, Ecuador | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat
14.473°N, 90.880°W; summit elev. 3763 m
INSIVUMEH reported that during 19-21 September explosions from Fuego ejected incandescent material 100 m above the crater and produced ash plumes that rose 500-1,000 m. Incandescent avalanches traveled 600 m down the flanks. Ashfall was reported at the observatory, and in Morelia (8 km SW) and Santa Sofia (12 km SE). During 22-25 September explosions generated ash plumes that rose 300-800 m above the crater and drifted 6-10 km NE, N, and NW. Incandescent material was ejected 75-150 m above the crater, and avalanches descended the Ceniza and Taniluyá drainages (SSW).
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 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 historical eruptions 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.
LITTLE SITKIN, Aleutian Islands
51.95°N, 178.543°E; summit elev. 1174 m
AVO reported that during 19-24 September seismic activity at Little Sitkin remained elevated and satellite views were mostly obscured by clouds. On 21 September AVO noted that the frequency of earthquakes had declined during the previous week. 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.
1.358°N, 124.792°E; summit elev. 1580 m
According to the Darwin VAAC, ground-based observers reported that on 21 September an ash plume from Lokon-Empung rose to an altitude of 3 km (10,000 ft) a.s.l. Ash was not identified in satellite imagery.
Geologic summary: The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2.2 km apart) has a flat, craterless top. The morphologically younger Empung volcano has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m wide double crater situated in the saddle between the two peaks. Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-domegrowth and pyroclastic flows have also occurred.
1.108°N, 124.73°E; summit elev. 1784 m
Based on information from the US Air Force Weather Agency (AFWA), the Support to Aviation Control Service (SACS), and CVGHM, the Darwin VAAC reported that an ash plume from Soputan rose to an altitude of 9.1 km (30,000 ft) a.s.l. on 19 September. Later that day an ash plume rose to an altitude of 2.4 km (8,000 ft) a.s.l.
Geologic summary: The small conical volcano of Soputan on the southern rim of the Quaternary Tondano caldera is one of Sulawesi’s most active volcanoes. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.
TANGKUBANPARAHU, Western Java (Indonesia)
6.77°S, 107.60°E; summit elev. 2084 m
CVGHM reported that during 23 August-21 September shallow volcanic earthquakes continued to be recorded at Tangkubanparahu but were less frequent. Other types of seismic signals also decreased. Based on seismicity, visual observations, deformation data, gas measurements, and soil and crater lake water temperatures, the Alert Level was lowered to 1 (on a scale of 1-4) on 21 September.
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 on 25 September an ash plume from Batu Tara rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 28 km 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.
1.22°N, 77.37°W; summit elev. 4276 m
INGEOMINAS reported that during 18-22 and 24-25 September cameras around Galeras recorded emissions that were mostly water vapor. On 18 and 24 September the emissions contained ash. An earthquake swarm detected on 25 September was characterized by events less than M 1 that occurred 2 km W of the crater at depths near 3 km. The Alert Level remained at III (Yellow; “changes in the behavior of volcanic activity”).
Geologic summary: Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia’s most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Longterm extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.
KARYMSKY, Eastern Kamchatka (Russia)
54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported weak-to-moderate seismic activity from Karymsky during 14-21 September. Seismic data indicated that ash plumes possibly rose to an altitude of 5.5 km (18,000 ft) a.s.l. Satellite imagery showed a thermal anomaly on the volcano on 19 September. The Aviation Color Code remained at Orange.
Geologic summary: Karymsky, the most active volcano of Kamchatka’s eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed 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 19-25 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. Lava flows were active above the abandoned Royal Gardens subdivision and began to flow down the pali. At Pu’u ‘O’o Crater, incandescence from the S and E pits on the crater floor, and from the W edge of the crusted N pit, was often visible. An opening in the roof of the lava tube at the base of the SE flank of Pu’u ‘O’o also continued to glow.
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.
0.077°S, 77.656°W; summit elev. 3562 m
Based on analysis of satellite imagery, the Washington VAAC reported that an ash plume from Reventador drifted 22 km SW on 20 September.
Geologic summary: Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera.
31.585°N, 130.657°E; summit elev. 1117 m
JMA reported that during 15-21 September explosions from Sakura-jima’s Showa Crater ejected tephra as far as 1.3 km from the crater. Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 19-20 and 22-24 September often produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. The plumes sometimes drifted NE, E, SE, S, and SW. On 19 September a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted SE.
Geologic summary: Sakura-jima, one of Japan’s most active volcanoes, is a post-caldera cone of the Airacaldera 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 14-21 September a viscous lava flow continued to effuse on the NW flank of Shiveluch’s lava dome, and was accompanied by hot avalanches and fumarolic activity. A strong explosion on 18 September generated an ash plume that rose to an altitude of 8 km (26,300 ft) a.s.l. An ash plume rose to an altitude of 3.5 km (11,500 ft) a.s.l. on 20 September. Satellite imagery showed a thermal anomaly on the lava dome on 14 and 19 September, and an ash plume drifting 2,000 km SE during 17-20 September. 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 historicaleruptions from Shiveluch occurred in 1854 and 1964.
SOUFRIERE HILLS, Montserrat
16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 14-21 September activity at the Soufrière Hills lava dome was at a low level, although multiple rockfalls originated from the W side of the lava dome. The largest event generated a pyroclastic flow that traveled 1 km. Overhanging areas on both on the E and W faces of the dome were observed. 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.
Source: Global Volcanism Program
Featured image: Little Sitkin. Credit: Alaska Dispatch
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