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SI/USGS Weekly Volcanic Activity Report, 22 April 2009 – 28 April 2009 30 April 2009

Posted by admin in activity reports, Alaska, Bagana, Barren Island, Batu Tara, Caribbean, Chaitén, Chile, Colombia, Dukono, Ebeko, Ecuador, eruptions, Galeras, Guatemala, Hawaii, Indonesia, Japan, Kamchatka, Karymsky, Kerinci, Kilauea, Koryaksky, Krakatau, Llaima, Pacaya, Papua New Guinea, Rabaul, Redoubt, Reventador, Russia, Sakura-jima, Santa María, Shiveluch, Slamet, Soufrière Hills, Suwanose-jima, Tungurahua, United States, Weekly Volcanic Activity Reports.
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SI/USGS Weekly Volcanic Activity Report 22 April 2009 - 28 April 2009

The Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 22 April 2009 to 28 April 2009 is available on the Global Volcanism Program website. The following is a summary and not a substitute for the full report.

New activity: Bagana (Papua New Guinea), Ebeko (Paramushir Island, Russia), Galeras (Colombia), Pagan (Mariana Islands), Reventador (Ecuador), Shiveluch (Kamchatka, Russia), Slamet (Java, Indonesia).

Ongoing activity: Barren Island (Andaman Islands), Batu Tara (Komba Island, Indonesia), Chaitén (Chile), Dukono (Halmahera, Indonesia), Fuego (Guatemala), Karymsky (Kamchatka, Russia), Kerinci (Sumatra, Indonesia), Kilauea (Hawaii, USA), Koryaksky (Kamchatka, Russia), Krakatau (Indonesia), Llaima (Chile), Pacaya (Guatemala), Rabaul (Papua New Guinea), Redoubt (Alaska, USA), Sakura-jima (Japan), Santa María (Guatemala), Soufrière Hills (Montserrat), Suwanose-jima (Japan), Tungurahua (Ecuador).

NEW ACTIVITY

Bagana (Papua New Guinea). An ash plume from Bagana was reported on 26 April, rising to 2.4 km a.s.l. and drifting 28 km south.

Ebeko (Paramushir Island, Russia). Continuing activity was observed over the period 17-24 April, with gas-and-steam plumes with some ash content rising to 2 km a.s.l. and drifting north-east during 17-19 April. Light ash fall occurred in Severo-Kurilsk (7 km to the east) on 22 April, and on 25-26 April ash plumes rose to 1.2-2.1 km a.s.l. and drifted south, south-west and west.

Galeras (Colombia). Two explosive eruptions occurred on 24 April: the first produced a shock wave detected up to 25 km away, and incandescent blocks were ejected causing firest on the north flank. About 30 minutes later a second eruption took place, less energetic than the first but longer lasting. Incandescence from both eruptions was visible from Pasto, 10 km to the east. An ash plume rose to 10.3 km a.s.l., and ashfall was reported in areas to the west, up to 20 km distant. On 25 April ash-and-gas plumes rose 1 km above the crater.

Pagan (Mariana Islands). Continuous steam emissions were reported from the north crater during 21-22 April, and a diffuse plume drifting 15 km west was detected on 23 April. Steam emissions had decreased on 28 April.

Reventador (Ecuador). An earthquake swarm was detected at Reventador on 26 March, followed by a decrease in seismicity to low levels. Seismicity increased on 23 April, with long-period events interspersed with bands of spasmodic and harmonic tremor, and steam plumes with low ash content rose to 5.6-6.6 km a.s.l. and drifted west. Satellite imagery revealed a thermal anomaly and a steam plume drifting 26 km west-south-west.

Shiveluch (Kamchatka, Russia). Seismic activity was elevated over 17-24 April, ash plumes probably rose to 4.5-5.3 km a.s.l., and satellite imagery revealed a daily thermal anomaly
on the lava dome. Fumaroles were reported to be active during 16-22 April, and a hot avalanche produced an ash plume to 4 km a.s.l. on 22 April. [More recent activity at Shiveluch is not covered by this SI/USGS report.]

Slamet (Java, Indonesia). During 19-23 April seismicity increased, diffuse white plumes rose about 50 m above the crater on 20 April, white and white-to-brownish plumes rose 50-800 m above the crater during 21-23 April. Press stories quoted a volcanologist’s report of lava being ejected up to 600 m and bursts of ash occurring up to 112 times over a 6-hour period.

ONGOING ACTIVITY

Barren Island (Andaman Islands). Ash plumes reported to 2.4 km a.s.l. and drifting 45-65 km north-east, east and south-east during 23-25 April.

Batu Tara (Komba Island, Indonesia). Ash plumes reported to 3 km a.s.l. and drifting up to 110 km in ‘multiple directions’ during 24-25 and 28 April.

Chaitén (Chile). During 15-21 April gas-and-ash plumes rose 1.5 km from the lava dome complex and seismicity remained elevated, with earthquakes up to magnitude 4.5 recorded. Ash plumes to 2.1-3 km a.s.l. and drifting north-east and north were reported on 25 and 28 April.

Dukono (Halmahera, Indonesia). Ash plume to 4.5 km a.s.l., drifting 150 km east, reported on 28 April.

Fuego (Guatemala). Explosions on 24 and 28 April produced ash plumes to 4.1-4.8 km a.s.l. that drifted 10 km south-west; rumbling noises and shock waves from some explosions were detected 5 km away; avalanches of blocks descended the flanks; and fumarolic plumes rose 50-150 m and drifted south, north-west and north. On 28 April, incandescent material was ejected 75-100 m into the air.

Karymsky (Kamchatka, Russia). Fumarolic activity was observed over 17-24 April, and a thermal anomaly on the volcano was detected on 17 April.

Kerinci (Sumatra, Indonesia). Increased seismicity was detected at Kerinci in early April, accompanied by light and dark plumes rising up to 500-600 m above the crater during 1-20 April. Ashfall occurred at a nearby observation post on 19 April, and ‘noises indicative of an eruption’ were heard at same location on 19-20 April.

Kilauea (Hawaii, USA). During 22-28 April lava continued to flow south-east through a lava tube system to the Waikupanaha (where occasional explosions occurred) and Kupapa’u (where a littoral cone is being built up) ocean entries. Surface flows were present on the coastal plain. The Halema’uma’u crater vent continued to produce a white plume with occasional brown tinges that drifted south-west, north and north-east, and incandescence was intermittently observed.

Koryaksky (Kamchatka, Russia). Seismic activity was reported to be above background levels and weak volcanic tremor was present over 17-25 April. Gas plumes with small quantities of ash drifted in multiple directions over 17-18 April; satellite imagery on the same dates detected gas-and-ash plumes that drifted 100 km north-east. A sulphur dioxide plume was detected extending about 15 km from the volcano. Seismic activity decreased to background levels, with occasional tremor, over 25-28 April.

Krakatau (Indonesia). Local residents reported increases in activity and some evacuated themselves, but the volcanological authorities said nothing unusual was going on. Loud blasts, lava flows and ash plumes rising to 200-800 m above Anak Krakatau crater were reported.

Llaima (Chile). On 24 April ash plumes were observed at an area on the east flank about 700 m below the crater for a period of about 1.5 hours. The presence of steam indicated sub-glacial activity.

Pacaya (Guatemala). On 24 and 28 April, gas emissions from MacKenney cone and occasional ash explosions ejecting tephra 15-25 m were observed, and the seismic network detected tremor and explosions. Rumbling sounds were audible 3-5 km away. Lava flows descended the south-west flank for 50-400 m and fumarolic plumes drifted south.

Rabaul (Papua New Guinea). Tavurvur cone produced white and grey plumes to 0.5-1.5 km above the crater which drifted east and south-east during 18-25 April. Incandescence was visible at night and occasional roaring noises were heard. Ashfall was reported about 20 km south-east and in surrounding areas. Ash plumes were reported to have risen to 3 km a.s.l. and drifted 55 km south and 35 km south-west on 27 and 28 April.

Redoubt (Alaska, USA). The lava dome at Redoubt continues to grow, with seismicity remaining at background levels over 22-28 April. Steam-and-gas plumes occasionally with small amounts of ash were observed on 22 April, and sulphurous odours were reported by pilots to the north-east on 22 and to the south on 28 April.

Sakura-jima (Japan). Things seem to be quietening down, with no large eruptions since 11 April, no deformation reported and low seismicity. The alert level was lowered from 3 to 2 on 24 April.

Santa María (Guatemala). The number of explosions from the Santiaguito lava dome complex has reportedly decreased over the last few weeks. During 24-28 April explosions at Santiaguito produced ash plumes drifting 5-8 km west-south-west, and gas plumes rose 25-75 m above Caliente dome.

Soufrière Hills (Montserrat). Over 17-24 April activity from the lava dome was at a low level. A small pyroclastic flow descended eastwards along the Tar River valley on 24 April.

Suwanose-jima (Japan). An ash plume was reported on 22 April, and an eruption on 23 April reportedly produced ash plumes to 1.2-1.5 km a.s.l. and drifted east and south, and an explosion was reported on 27 Apri. Explosions on 28 April produced plumes to 1.5-1.8 km a.s.l. which drifted east.

Tungurahua (Ecuador). Steam-and-gas plumes with occasional ash content rose to 6.5 km a.s.l. and drifted south-west and west during 22-28 April. Ashfall occurred to the south-west on 21 April, incandescence was seen from the crater over 21-22 April, incandescent blocks were ejected on 22 April. A lahar descended the Patacocha drainage on 25 April.

ACKNOWLEDGEMENTS AND DISCLAIMER

The foregoing is a summary of the Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 22 April to 28 April 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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