Active volcanoes in the world from 21/09/2011 to 27/09/2011

From Earthquake Report: Active volcanoes in the world from 21/09/2011 to 27/09/2011

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 every Week (mostly 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 of 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 or ACTIVITY CHANGE
HIERRO Canary Islands (Spain) 27.73°N, 18.03°W; summit elev. 1500 m
Instituto Geográfico Nacional (IGN) reported more than 900 new seismic events at Hierro during 20-26 September, five of them felt by residents. The maximum magnitude recorded was 3.4. The total number of located events had reached more than 8,100 since the anomalous activity began on 16 July. The rates of both GPS deformation and seismic energy release had significantly increased during the previous seven days. On 23 September, the Canarian Autonomous Government raised the Alert Code to Yellow.
Hierro Information. The triangular island of Hierro is the SW-most and least studied of the Canary Islands. The massive Hierro shield volcano is truncated by a large NW-facing escarpment formed as a result of gravitational collapse of El Golfo volcano about 130,000 years ago.

The steep-sided 1500-m-high scarp towers above a low lava platform bordering 12-km-wide El Golfo Bay, and three other large submarine landslide deposits occur to the SW and SE. Three prominent rifts o21ented NW, NE, and south at 120 degree angles form prominent topographic ridges. The subaerial portion of the volcano consists of flat-lying Quaternary basaltic and trachybasaltic lava flows and tuffs capped by numerous young cinder cones and lava flows. Holocene cones and flows are found both on the outer flanks and in the El Golfo depression. Hierro contains the greatest concentration of young vents in the Canary Islands. Uncertainty surrounds the report of an historical eruption in 1793.

LEWOTOBI Flores Island (Indonesia) 8.542°S, 122.775°E; summit elev. 1703 m
CVGHM raised the Alert Level for Lewotobi Lakilaki, one of two stratovolcanoes composing Lewotobi, to 2 (on a scale of 1-4) on 22 September due to increased seismicity since 17 September and visual observations. Although no significant changes in the volcano were observed, diffuse white plumes rose 15 m above the crater. Visitors and residents were prohibited from going within a 1-km radius of Lewotobi Lakilaki.
Lewotobi Information. The Lewotobi "husband and wife" twin volcano (also known as Lewetobi) in eastern Flores Island is composed of the Lewotobi Lakilaki and Lewotobi Perempuan stratovolcanoes. Their summits are less than 2 km apart along a NW-SE line. The conical 1,584-m-high Lewotobi Lakilaki has been frequently active during the 19th and 20th centuries, while the taller and broader 1,703-m-high Lewotobi Perempuan has erupted only twice in historical time. Small lava domes have grown during the 20th century in the crescentic summit craters of both volcanoes, which are open to the N. A prominent flank cone, Iliwokar, occurs on the E flank of Lewotobi Perampuan.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM)

POPOCATEPETL México 19.023°N, 98.622°W; summit elev. 5426 m
During 21-25 September CENAPRED reported steam-and-gas emissions from Popocatépetl. An explosion on 26 September ejected incandescent fragments and produced an ash plume that rose 2.5 km above the crater. Following the explosion, a series of 11 gas-and-steam plumes containing small amounts of ash rose from the crater.
Popocatépetl Information. 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.

ONGOING ACTIVITY
BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 21-24 September ash plumes from Batu Tara rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 37-65 km W, WNW, and NW.

CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m
AVO reported that during 20-21 September no observations of elevated surface temperatures or ash emissions from Cleveland were visible in partly cloudy satellite images. Clouds obscured views on 22 September. Elevated surface temperatures were observed in satellite images during 23-24 September, suggesting that the lava dome eruption was continuing. On 25 September AVO noted that elevated surface temperatures were not observed in several clear views of the volcano by satellite during the previous 24-hour period. Cloud cover prevented observations on 26 September.

DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m
Based on analyses of satellite imagery, the Darwin VAAC reported that on 27 September ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 75 km NW and NE.

KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that seismic activity continued at a moderate level at Karymsky during 16-23 September and indicated that possible ash plumes rose to altitudes of 5-6 km (16,400-19,700 ft) a.s.l. during 16-17 September. A thermal anomaly was detected in satellite imagery during 16, 18, and 20 September. The Aviation Color Code remained at Orange.

KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 21-27 September, HVO reported that the lava lake circulated and periodically rose and fell in the deep pit within Kilauea's Halema'uma'u crater. Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash and occasionally fresh spatter nearby.

At the E rift zone, lava in the W lava lake in Pu'u 'O'o Crater fed a series of lava flows that traveled down the W flank of Pu'u 'O'o during 20-21 September. At about 0225 on 21 September activity in the crater and overflows to the W suddenly decreased, as lava broke through the upper E flank of Pu'u 'O'o, bypassing the crater. The new fissure fed a channelized 'a'a lava flow that advanced rapidly downslope 2.5 km SE. A second flow to the W of the first began the next day. In addition, a small pad of lava actively refilled the bottom of the drained E lava lake and small flows were barely active at the W edge of Pu'u 'O'o Crater. The channelized 'a'a lava flow reached 3.7 km long on 23 September and then stalled within the Kahauale'a Natural Area Reserve. Most of the active lava spread S and W of Pu'u Halulu (1.3 km NE of Pu'u 'O'o) during 23-27 September. Minor lava activity resumed within Pu'u 'O'o Crater with short lava flows issuing from the base of the E wall on 25 September and from the W wall base during 25-26 September. The crater floor of Pu'u 'O'o slowly subsided. Lava activity resumed within the E lake on 26 September. The floor of the crater continued to subside during 26-27 September, opening up cracks in the N crater floor.

KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m
KVERT reported that during 16-23 September volcanic tremor magnitude at Kizimen continued to increase; 1,400-1,600 earthquakes were recorded daily. A thermal anomaly on the volcano was detected in satellite images. Lava on the E flank continued to flow and video images showed strong fumarolic activity. The Aviation Color Code remained at Orange.

PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m
Based on seismicity during 21-26 September, OVDAS-SERNAGEOMIN reported that the eruption from the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex, continued at a low level. Plumes observed by an area camera rose 3-5 km above the crater during 21-23 and 25 September and were visible in satellite images drifted 30-300 km NE, E, and SE during 21-26 September. The Alert Level remained at Red.

SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
Based on information from JMA, the Tokyo VAAC reported that during 21-27 September explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted SE, S, and W. On 22 September a pilot observed an ash plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SE.

SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that seismic activity at Shiveluch was moderate during 16-23 September. A thermal anomaly on the volcano was also observed in satellite imagery on 15 and 18 September. Ground-based observers noted fumarolic activity during 18-20 September. The Aviation Color Code remained at Orange.
Based on information from KEMSD, the Tokyo VAAC reported that on 24 September an eruption produced a plume that rose to an altitude of 6.4 km (21,000 ft) a.s.l. and drifted E. Subsequent images that day showed that the ash had dissipated.

SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 16-23 September activity at the Soufrière Hills lava dome was at a low level. On 19 September a pyroclastic flow occurred from the W side of the lava dome. The Hazard Level remained at 3.