Active volcanoes in the world: September 18 – September 24, 2013

During past seven days 4 volcanoes had new activity, ongoing activity was reported for 9 volcanoes. This report covers active volcanoes in the world from September 18 – September 24, 2013 based on Smithsonian/USGS criteria.

New activity/unrest: | Lokon-Empung, Sulawesi | Sakura-jima, Kyushu | Santa María, Guatemala | Sinabung, Sumatra (Indonesia)

Ongoing activity: | Bagana, Bougainville | Batu Tara, Komba Island (Indonesia) | Dukono, Halmahera | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Reventador, Ecuador | Shiveluch, Central Kamchatka (Russia) | Veniaminof, Alaska Peninsula

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.

New activity/unrest

LOKON-EMPUNG, Sulawesi 
1.358°N, 124.792°E; summit elev. 1580 m

According to a news article, a spokesperson from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) stated that activity at Lokon-Empung continued to decline after a 9 September eruption. The frequency of deep and shallow volcanic earthquakes had continued to decline.

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-dome growth and pyroclastic flows have also occurred.

SAKURA-JIMA, Kyushu 
31.585°N, 130.657°E; summit elev. 1117 m

JMA reported that 18 explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m during 17-20 September. Incandescence from the crater was visible some nights. Based on information from JMA and pilot observations, the Tokyo VAAC reported that during 18-20 and 22-23 September explosions generated plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l., and drifted SW, W, and NW.

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 17-18 September explosions from Santa María's Santiaguito lava-dome complex produced ash plumes that rose 900 m and drifted W. Block avalanches descended the E flank of Caliente cone. Degassing sounds were reported during 19-21 September; gas plumes rose 150 m and drifted SW on 21 September. At 0820 on 21 September explosions from Caliente cone collapsed part of the SE crater rim, produced an ash plume that rose 2 km and drifted N and NE, and generated pyroclastic flows that descended the flanks. A strong shock wave was detected 20 km away and shook structures within 10 km.  Explosions on 23 September produced ash plumes that rose 700 m and drifted E. Block avalanches again descended the E flank of Caliente cone. Two explosions on 24 September generated light gray ash plumes that rose 500 m and caused ashfall in areas around Monte Claro (S).

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.

SINABUNG, Sumatra (Indonesia)
3.17°N, 98.392°E; summit elev. 2460 m

According to the Darwin VAAC, the webcam recording activity at Sinabung showed on 18 September that ash had dissipated. The VAAC also noted that PVMBG confirmed Sinabung was degassing and not emitting any ash. According to a news article, about 6,000 people that had evacuated after the 15 September eruption started to return home on 22 September. The article noted that the volcano was continuing to emit ash.

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 of Sinabung in 1912, although no confirmed historical eruptions were recorded prior to 2010.    

Ongoing activity

BAGANA, Bougainville 
6.140°S, 155.195°E; summit elev. 1750 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 19 September an ash plume from Bagana rose to an altitude of 2.7 km (8,000 ft) a.s.l. and drifted 75 km W.

Geologic summary: Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50-m-thick with prominent levees that descend the volcano's flanks on all sides.

BATU TARA, Komba Island (Indonesia)
7.792°S, 123.579°E; summit elev. 748 m

Based on analyses of satellite imagery and wind data, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 18-21 September ash plumes from Batu Tara rose to altitudes of 2.1-2.7 km (7,000-9,000 ft) a.s.l. and drifted 35-100 km WSW, W, NW, N, and NE.

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.

DUKONO, Halmahera
1.68°N, 127.88°E; summit elev. 1335 m

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 23 September an ash plume from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 75 km NE.

Geologic summary: Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

KARYMSKY, Eastern Kamchatka (Russia)
54.05°N, 159.45°E; summit elev. 1536 m

KVERT reported that moderate seismic activity at Karymsky was detected during 13-20 September, and weak ash explosions likely occurred. 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 18-24 September HVO reported that the circulating lava lake occasionally rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. The plume from the vent continued to deposit variable amounts of ash, spatter, and Pele's hair onto nearby areas. At Pu'u 'O'o Crater, glow emanated from spatter cones on the N and S portions of the crater floor. The 3.6-km-long Kahauale’a 2 lava flow, fed by the NE spatter cone, was active with scattered break-out flows and burned the forest N of Pu'u 'O'o. Peace Day activity, fed by lava tubes extending from Pu'u 'O'o, consisted of a few breakouts; during an overflight on 19 September geologists observed two small breakouts 2.7 km and 6 km SE of Pu'u 'O'o above the pali.

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.

KLIUCHEVSKOI, Central Kamchatka (Russia) 
56.057°N, 160.638°E; summit elev. 4850 m

KVERT reported that moderate seismic activity at Kliuchevskoi was detected during 13-20 September. A video camera recorded incandescence from the summit and the WSW flank at night, and gas-and-steam plumes containing minor amounts of ash. Strombolian the activity continued and a lava flow effused onto the W and SW flanks. A large thermal anomaly from the lava dome was detected daily in satellite images. The Aviation Color Code remained at Orange.

Geologic summary: Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. Kliuchevskoi rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred at Kliuchevskoi during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

REVENTADOR, Ecuador 
0.077°S, 77.656°W; summit elev. 3562 m

IG reported that seismicity remained elevated at Reventador during 18-24 September. Although cloud cover often prevented observations, ash plumes were occasionally observed. On 19 September an ash plume drifted W, and on 21 September multiple low-energy steam emissions contained small amounts of ash. Deposits from a pyroclastic flow that had descended the S flank were observed on 22 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.

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 13-20 September a viscous lava flow effused onto the N and NW flanks of Shiveluch's lava dome, accompanied by hot avalanches, incandescence, ash explosions, and fumarolic activity. A thermal anomaly was detected in satellite images during 15-16 September; clouds obscured views on the other days. Video data showed that at 1454 on 20 September an ash plume rose to altitudes of 5-5.5 km (16,400-18,000) a.s.l. and drifted 20 km NE. 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.

VENIAMINOF, Alaska Peninsula
56.17°N, 159.38°W; summit elev. 2507 m

On 20 September AVO reported that, based on a decrease in seismicity at Veniaminof and no eruptive activity observed by satellite or the web camera over the previous week, the Aviation Color Code was lowered to Yellow and the Volcano Alert Level was lowered to Advisory. Low-level seismic tremor continued during 21-24 September.

Geologic summary: Massive Veniaminof volcano, one of the highest and largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 years ago. The caldera rim is up to 520 m high on the N, is deeply notched on the W by Cone Glacier, and is covered by an ice sheet on the S. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which reaches an elevation of 2,156 m and rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.

Source: GVP