New unrest has been noticed around 6 volcanoes, ongoing activity was reported for 11 volcanoes. This report covers active volcanoes in the world recorded from August 22 – August 28, 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 2300 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.
HAVRE SEAMOUNT, Kermadec Islands (SW Pacific)
According to NASA's Earth Observatory, a satellite image acquired on 24 August showed linear clusters of pumice, from the mid-July eruption from Havre Seamount, floating in the ocean around L'Esperance Rock (about 50 km SE).
Note: Havre Seamount is not currently in the Global Volcanism Program's database. The latitude and longitude in the header information come from the GNS report and may be updated at a later date, along with the summit elevation and Geologic Summary.
GROZNY GROUP, Iturup Island
45.026°N, 147.922°E; summit elev. 1211 m
Based on analyses of satellite imagery, SVERT reported that on 22 August a gas-and-ash plume rose 500 m above Grozny Group and drifted 15 km NE. Fumarolic activity increased during 23-25 August. Observers reported that an ash plume rose to 5 km (16,400 ft) a.s.l. on 25 August. That same day the Tokyo VAAC reported that a possible eruption from Etorofu-Yake-yama, a lava dome of the Grozny Group, may have produced a plume that rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted E.
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 otherlava 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.
1.108°N, 124.73°E; summit elev. 1784 m
CVGHM reported that the Alert Level for Soputan had been lowered to 2 (on a scale of 1-4) on 26 June. Seismicity increased during 8-22 August; on 23 August volcanic earthquakes and avalanches significantly increased. White plumes rose 50-150 m above the crater. An eruption at 1936 on 26 August ejected incandescent tephra 50 m above the crater and produced a plume that rose 1 km and drifted W. The Alert Level was raised to 3.
Based on information from CVGHM, NOAA, and analysis of satellite imagery, the Darwin VAAC reported that on 27 August an ash plume rose to an altitude of 12.1 km (40,000 ft) a.s.l. and drifted 150 km W. The eruption lasted four hours. Later, a plume detected in satellite imagery rose to an altitude of 6.1 km (20,000 ft) a.s.l. On 28 August an ash plume drifted 220 km SW at an altitude of 6.1 km (20,000 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.
SOUFRIERE HILLS, Montserrat
16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 13-20 July activity at the Soufrière Hills lava dome was generally at a low level. Seismicity had slightly increased, and was at the highest level since the ash-venting episode in March, but remained consistent with a pause in lava extrusion. 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 increased significantly on 13 August; earthquakes continued to be recorded through 23 August. The Alert Level was raised to 2 (on a scale of 1-4). Visitors and residents were prohibited from going within a 1.5-km radius of the active crater.
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.
1.467°S, 78.442°W; summit elev. 5023 m
IG reported that at about noon on 21 August Tungurahua entered a second stage of activity since the onset of the eruption that began early in August. The second stage was characterized by low-to-moderate levels of activity; emissions decreased and intense seismic tremor declined to sporadic episodes lasting only a few minutes. During 22-28 August visual observations were often limited due to cloud cover. On 22 August steam-and-gas plumes rose from the crater, roaring was heard, and ashfall was reported in Choglontús (SW). Explosions at night ejected incandescent tephra that landed on the flanks 500 m below the crater. The next day gas-and-ash plumes rose 1.5-4 km above the crater and drifted W and NW. Ashfall was reported in Choglontús, Pillate (7 km W), and El Tablón. On 24 August gas-and-ash plumes rose 2 km and drifted W. During 24-25 August ash fell in Manzano (8 km SW), Choglontus, Chacauco (NW), Bilbao (8 km W), and Pillate. Explosions on 26 August generated ash-and-gas plumes that rose 2-3 km and drifted NW.
Geologic summary: The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano.
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 22 August ash plumes from Batu Tara rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 45 km W. During 25-7 August ash plumes rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted 35-110 km W.
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
AVO reported that nothing unusual was observed at Cleveland in cloudy to partly cloudy satellite images during 22-26 August. Slightly elevated surface temperatures were detected at the summit during 23-24 August. Cloud cover prevented observations during 27-28 August. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.
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
INSIVUMEH reported that on 22 August the seismic network at Fuego detected lahars that traveled SE down the Las Lajas and El Jute drainages. During 22-27 August lava flows traveled 150-300 m down the Taniluyá drainage (SW) and as far as 400 m down the Ceniza drainage (SSW), generating incandescent block avalanches that reached vegetated areas. Incandescent material was ejected 100 m above the crater. White plumes rose to low heights and drifted SW, W, and NW.
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.
1.22°N, 77.37°W; summit elev. 4276 m
INGEOMINAS reported that during 21-28 August seismicity at Galeras increased. Sulfur dioxide emissions fluctuated, but remained at low-to-moderate levels. Cameras around the volcano recorded emissions during 21-26 August; the emissions contained ash on 26 August. 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 moderate seismic activity from Karymsky during 17-27 August, and indicated that possible ash plumes rose to an altitude of 5.8 km (19,000 ft) a.s.l. on 25 August and to an altitude of 2.4 km (7,900 ft) a.s.l. on 27 August. Satellite imagery showed a daily thermal anomaly on the volcano. The Aviation Color Code remained at Orange.
Based on information from KEMSD, the Tokyo VAAC reported that on 25 August an eruption produced a plume that rose to an altitude of 5.8 km (19,000 ft) a.s.l. The altitude was based on seismic analysis.
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 22-28 August 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 likely continued to deposit variable amounts ofspatter and Pele's hair onto nearby areas. There were no significant geologic changes in Pu'u 'O'o Crater; incandescence emanated from a lava lake in a pit on the NE part of the crater floor, from a pit crater on the S part of the crater floor, and from a vent at the base of the SE flank. The vent on the S part of the crater floor produced a small lava flow on 26 August. Lava flows were active on the pali and the coastal plain, and were as close as 2 km from the ocean on 28 August.
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.
NEVADO DEL RUIZ, Colombia
4.895°N, 75.322°W; summit elev. 5321 m
According to INGEOMINAS, the Observatorio Vulcanológico and Sismológico de Manizales reported that during 22-28 August variations in volcanic tremor amplitude were detected at Nevado del Ruiz, possibly associated with continuing gas and ash emissions. Cameras located near the volcano showed gas plumes rising 800 m above the crater and drifting NE on 23 August, and rising 1 km the next day. Gas plumes rose 300-500 m and drifted W and N during 26-28 August. Field measurements and analysis of satellite imagery showed a significant amount of sulfur dioxide in the atmosphere during 24 and 26-27 August. The Alert Level remained at II (Orange; "eruption likely within days or weeks").
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.
19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED reported that during 22-28 August seismicity at Popocatépetl indicated continuing gas-and-steam emissions that may have contained ash; cloud cover often prevented visual observations of the volcano. During 22-28 August gas-and-steam plumes rose from the crater, and drifted WSW, W, and WNW during 22-24 August. Incandescence from the crater was observed at night during 23-26 August. Bluish steam-and-gas plumes rose from the crater on 27 August. At 2233 an explosion produced an ash plume and ejected incandescent tephra that fell back into the crater. More robust emissions that rose 500 m were sometimes accompanied by incandescence from the crater. Later a plume rose 1.5 km. The next day bluish steam-and-gas plumes rose 1.2 km. The Alert Level remained at Yellow, Phase Three.
Geologic summary: Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America's second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages.
31.585°N, 130.657°E; summit elev. 1117 m
JMA reported that during 20-24 August eight explosive eruptions from Sakura-jima's Showa Crater were detected and ejected tephra as far as 1.8 km from the crater. Gas measurements taken on 20 and 22 August showed elevated sulfur dioxide emissions compared to the previous week. Based on information from JMA, the Tokyo VAAC reported that explosions during 22-26 August produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted N, NW, and W. Explosions were detected on 28 August.
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.
SANTA MARIA, Guatemala
14.756°N, 91.552°W; summit elev. 3772 m
INSIVUMEH reported that during 22-26 August explosions from Santa María's Santiaguito lava-dome complex produced ash plumes that rose 700 m above Caliente dome and drifted SW. Block avalanches originated from the fronts of multiple active flows, particularly on the SE flank. Fumarolic plumes rose 150-400 m and drifted SW. During 25-26 August ashfall was reported in Monte Claro (S). An explosion on 27 August produced a white plume that rose 600 m and drifted SE, causing ashfall in San Jose. Avalanches descended the SE flank.
Geologic summary: Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
SHIVELUCH, Central Kamchatka (Russia)
56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 17-24 August a viscous lava flow was active on the NE flank of Shiveluch's lava dome and was accompanied by hot avalanches. The summit of the dome was incandescent; satellite imagery showed a thermal anomaly over the area during 17-24 August. 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 Holocene within 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 andesitic volcano 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.
Source: Global Volcanism Program
Featured image: Soputan, Sulawesi
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