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SI/USGS Weekly Volcanic Activity Report 25 November – 1 December 2009 3 December 2009

Posted by admin in activity reports, Caribbean, Chaitén, Chile, Colombia, Dukono, Ecuador, eruptions, Fuego, Galeras, Gaua, Guatemala, Hawaii, Indonesia, Japan, Kamchatka, Karkar, Karymsky, Kilauea, Kliuchevskoi, Nevado del Huila, Pacific, Papua New Guinea, Rabaul, Russia, Sakura-jima, Sangay, Sarychev Peak, Shiveluch, Soufrière Hills, Suwanose-jima, United States, Vanuatu.
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SI/USGS Weekly Volcanic Activity Report 25 November - 1 December 2009

Click on the map for a larger version (1280 x 898 pixels).

The Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report for 25 November – 1 December 2009 is available on the Global Volcanism Program website. The following is a summary and not a substitute for the full report.

New activity/unrest: Galeras (Colombia), Gaua (Vanuatu), Karkar (Papua New Guinea), Sarychev Peak (Russia).

Ongoing activity: Chaitén (Chile), Dukono (Indonesia), Fuego (Guatemala), Karymsky (Russia), Kilauea (Hawaii, USA), Kliuchevskoi (Russia), Nevado del Huila (Colombia), Rabaul (Papua New Guinea), Sakura-jima (Japan), Sangay (Ecuador), Shiveluch (Russia), Soufrière Hills (Montserrat), Suwanose-jima (Japan).

Note: a.s.l. = ‘above sea level’.

NEW ACTIVITY/UNREST

Galeras (Colombia). The Alert Level for Galeras to was lowered from Orange to Yellow on 27 November after several days of low seismicity with occasional signals indicative of minor gas and ash emissions. An overflight on 26 November revealed gas emissions from the interior walls of the main crater and thermal anomalies with temperatures of 200 degrees Celsius. During 27 November-1 December, seismicity remained low and signals indicated gas emissions.

Gaua (Vanuatu). On 18 November a large explosion from Gaua’s Mount Garat was followed by high dense ash plumes. Seismicity increased on 25 October and remained significant through 24 November. According to news articles, an explosion that caused ashfall in inhabited areas on 26 November prompted the evacuation of more than 300 people. The Alert Level was raised to 4, the second highest level on a scale of 0-5. [Volcanism Blog note: There is no official confirmation of this reported rise in Alert Level. As of 3 December 2009 the Vanuatu Geohazards Observatory gives the Alert Level as 2 – although it should be noted that the VGO site is often slow in updating.]

Karkar (Papua New Guinea). On 25 November Darwin VAAC reported an eruption that produced a plume that to 13.7 km a.s.l., and stated that ash had merged with a thunderstorm cloud and had become unidentifiable. On 26 November another ash plume was reported to have risen to 9.1 km a.s.l. Confirmation of ash emissions was not available from RVO at the time of the posting of this report. [Volcanism Blog note: Local reports, and the lack of corroboration from other sources, strongly indicate that this eruption never took place. Darwin VAAC’s reports were almost certainly based on erroneous interpretations of satellite data.]

Sarychev Peak (Russia). A thermal anomaly on was detected by satellite on 25 November. Steam-and-gas emissions were noted on 25, 26 and 29 November.

ONGOING ACTIVITY

Chaitén (Chile). Buenos Aires VAAC reported that on 26 November a diffuse plume from the lava-dome complex drifted ENE.

Dukono (Indonesia). Darwin VAAC reported that on 30 November an ash plume from Dukono at 3 km a.s.l. was observed on satellite imagery 75 km E.

Fuego (Guatemala). Washington VAAC reported that on 29 November a small plume possibly containing ash, drifted 10 km SW. A thermal anomaly was also detected. On 30 November and 1 December, INSIVUMEH reported that explosions produced ash plumes that rose to 4.3-4.7 km a.s.l. and drifted 8-15 km W and SW. Rumbling noises were noted and incandescent block avalanches were generated.

Karymsky (Russia). Seismic activity was above background levels on 23 and 25 November; technical reasons mean data were not available on other days during 20-27 November. Elevated seismicity possibly indicated that ash plumes rose to 3.8 km a.s.l. Analyses of satellite imagery revealed a daily thermal anomaly and ash plumes that drifted 120 km E on 23 and 25 November. The Level of Concern Color Code remained at Orange.

Kilauea (Hawaii, USA). During 25 November-1 December lava flowed SE through a lava tube system from beneath the Thanksgiving Eve Breakout (TEB) and rootless shield complex, reaching the ocean at multiple locations between Waikupanaha and an area 700 m farther to the W. A small bench collapse may have occurred on 27 November. Thermal anomalies detected by satellite and visual observations revealed active surface lava flows on the coastal plain. Incandescence was occasionally seen on the Pu’u ‘O’o crater floor. The vent in Halema’uma’u crater continued to produce a white or off-white plume that drifted mainly SW and dropped small amounts of ash downwind. Incandescence originated from a lava pond deep in the vent cavity floor; the lava pond circulated and spattered during 25-26 November and 1 December. Measurements indicated that the sulphur dioxide emission rate at the summit remained elevated: 1,000 tonnes/day were measured on 28 and 30 November (2003-2007 average rate = 140 tonnes/day).

Kliuchevskoi (Russia). Seismic activity was above background levels and lava continued to flow down the ESE flank during 20-27 November. Strombolian activity ejected tephra 300 m above the crater during 21-25 November. Satellite imagery revealed a large daily thermal anomaly at the volcano. The Level of Concern Color Code remained at Orange.

Nevado del Huila (Colombia). During 25 November-1 December gas plumes rose 8.4 km a.s.l. and drifted downwind. Seismicity included both tremor indicative of gas emissions and hybrid earthquakes. An overflight on 25 November revealed that the newest lava dome had continued to grow. Based on pilot observations, the Washington VAAC reported that on 26 November a gas plume, possibly containing ash, rose to 7.6 km a.s.l. Ash was not identified in satellite imagery, although low weather clouds were present in the area. A sulphur dioxide plume was emitted on 30 November at a calculated rate of 3,900 tonnes/day.

Rabaul (Papua New Guinea). During 20-26 November thick white plumes and gray ash plumes rose from Tavurvur cone. Strong explosions produced ash plumes that rose 1.5 km above the summit and showered the flanks with lava fragments that were incandescent at night. Shock waves rattled windows in the Kokopo area, about 20 km SE. Occasionally, incandescence from the summit crater was noted.

Sakura-jima (Japan). Tokyo VAAC reported that explosions on 26 November and 1 December produced plumes that rose to 1.8-2.7 km a.s.l. and drifted SW and E. Ash was seen in satellite imagery on 26 November.

Sangay (Ecuador). Washington VAAC reported that on 1 December an ash plume rose to 7.9 km a.s.l. and drifted W. Ash was not identified in satellite imagery, although low weather clouds were present in the area. Later that day, an eruption was reported, but ash was again unidentifiable in satellite imagery.

Shiveluch (Russia). During 20-27 November seismic activity was above background levels, possibly indicating that ash plumes rose to 4.3 km a.s.l. Fumarolic activity was seen using a video camera. Analyses of satellite imagery revealed a large daily thermal anomaly from the lava dome. The Level of Concern Color Code remained at Orange.

Soufrière Hills (Montserrat). During 20-27 November activity from the lava dome continued at a high level. Activity increased on 21 November and periods of tremor were detected on 23 November. Lava extrusion during this period shifted from the W side of the lava dome to the summit region. As a result, abundant pyroclastic flows traveled NE down Tuitt’s Ghaut on 23 November for the first time in several weeks. On 24 November there was a period of 120 minutes of continuous pyroclastic flow activity, followed by 90 minutes of semi-continuous activity. The pyroclastic flows traveled W down Gages Valley and into Spring Ghaut, and NE down Tuitt’s Ghaut and Whites Bottom Ghaut reaching Tuitt’s village. Associated ash plumes rose to an altitude of 6.1 km a.s.l. On 26 November, a pyroclastic flow that descended the Tar River valley was caused by collapse of part of the old, pre-2009 lava dome. Ashfall occurred in Old Towne and parts of Olveston. Incandescent material seen in a photograph taken at night on 29 November traveled down the flanks of the lava dome in several areas. The Hazard Level remained at 3.

Suwanose-jima (Japan). Tokyo VAAC reported that on 26 November an ash plume was seen by a pilot 65 km S drifting NE at 3 km a.s.l.

ACKNOWLEDGEMENTS AND DISCLAIMER

The foregoing is a summary of the Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 25 November – 1 December 2009. It is provided for information only, and is based on but not a substitute for the full report, which comes with its own criteria and disclaimers. The map base is derived from the Smithsonian Institution/USGS/US Naval Research Laboratory This Dynamic Planet website.

For all our coverage of the SI/USGS Weekly Volcanic Activity Reports: Weekly Volcanic Activity Reports « The Volcanism Blog.

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