Sunday, March 29, 2009

Krakatau Volcano, Indonesia - John Seach

Activity has increased at Anak Krakatau volcano in Indonesia. Between 19-23 March 2009, an average of 6 shallow volcanic earthquakes were measured per day, compared to 2 per day over the past year. On 24th March, 31 shallow volcanic earthquakes were measured, and 62 earthquakes on 25th March, when visual observations showed white-gray emissions rising 400 m above the crater. Anak Krakatau remains at level 2 alert (waspada). A 1 km exclusion zone has been placed around the crater of Anak Krakatau. Locals have been advised that fishing is still permitted around the island.
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Chaiten Volcano, Chile - John Seach

Dome growth continues at Chaiten volcano in Chile. Between 17-23 March 2009, the lava dome at Chaiten produced constant degassing and release of water vapor, and varying amounts of ash. Gravitational collapse occurred in unstable areas. Dome growth is occurring mainly in the centre, which has formed a tall, hot and unstable spine. Ash emissions have reached Futaleufú, SE of the volcano. There has been a significant decrease in number and magnitude of earthquakes. Earthquake measurements indicate the dome continues to grow at a lower rate, with a very localized and shallow seismicity. Chaiten volcano remains on RED alert due to ongoing dome growth, and the possibility of collapse, leading to pyroclastic flows, some of which could extend into the Chaitén River valley.
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Redoubt Volcano Eruption, 2009 - John Seach

Seismic activity increased markedly at Redoubt volcano between 23-25 January 2009. Tremor became sustained and its amplitude increased. Aviation Color Code was increased to ORANGE. A burst of volcanic tremor occurred at Redoubt volcano, Alaska on Thursday 5th February 2009 at 11:18 am (local time). The tremor lasted 4 minutes and was the most intense since January 30th. A second episode of volcanic tremor occurred just after 3:00 PM on Wednesday and lasted for about 30 minutes. No eruption accompanied the earthquakes. An eruption occurred at Redoubt Volcano on 22nd March 2009, with ash emission to 50,000 ft above sea level. The volcano produced five explosive eruptions, each lasting from four to thirty minutes. Small amounts of ash fell at Skwentna, Talkeetna, Wasilla, and Trapper Creek. A large lahar occurred in the Drift River Valley and contained ice, water, mud, and other debris, and traveled more than 35 km to Cook Inlet. An eruption on 26th March ejected ash to a height of 65,000 ft. On 27th March ash reached 32,000 ft altitude. There were 11 large eruptions in the first week of activity with ash reaching altitudes of 30,000 to 60,000 ft.
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Friday, March 20, 2009

Tonga Earthquake (Magnitude 7.6) - John Seach

A major earthquake (Mag 7.6) hit Tonga on Friday 20th March 2009 at 06:17 hr, local time. The earthquake epicentre was located 280 km SSE of Hunga Tonga-Hunga Ha'apai Volcano, which began an undersea eruption three days ago. Sea level readings confirm that a tsunami was generated. The tsunami may have been destructive along coastlines of the region near the earthquake epicentre. A tsunami warning was issued for Tonga, Niue, Kermadec Islands, American Samoa, Samoa and Fiji.
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Wednesday, March 18, 2009

Undersea Eruption in Tonga, March 2009 - John Seach

An undersea eruption occurred west of the islands of Hunga Tonga and Hunga Ha'apai in Tonga. The eruption was visible from Nuku'alofa, the capital of Tonga. Steam and ash was emitted more than 1 km high. Residents said the steam and ash column first appeared on Monday morning, after a series of sharp earthquakes were felt in the capital, Nuku'alofa. Large amounts of pumice erupted by the volcano may reach beaches in Fiji in a short period of time.
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Saturday, March 14, 2009

Galeras Volcano, Colombia - John Seach

Galeras volcano in Colombia erupted on Friday 13th March (local time). forcing the evacuation of 3000 people. The explosive eruption occurred at 3:55 pm during a period of heavy rain and cloud which prevented visual observations. An eruption plume reached a height of 8 km above the summit, and drifted northwest. The seismic energy released was larger than the eruptions on 17th January 2008 and 14th February 2009, and and corresponds to about 75% of the energy released by the eruption of 20th January 2009.The eruption was heard from nearby communities of San Cayetano, Anganoy (Municipio de Pasto), San José de Bomboná and San Antonio (Municipio de Consacá). Ashfall was reported at Al Oriente Pasto (east and north), Anganoy, San Cayetano y Mapachico (north and northwest), Pachindo, Barranco, El Rodeo, the towns of Florida and Sandona. A strong smell of sulphurous gas has been reported in some areas.
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Friday, March 13, 2009

Semeru Volcano, Indonesia - John Seach

Activity has decreased at Semeru volcano in Indonesia, but scientists have warned this may be a dangerous situation. Volcanologists from Indonesian Centre of Volcanology and Geology have advised residents living near Semeru volcano to remain aware of eruptions, despite signs that volcanic activity is receding. Eruptions have decreased from 63 on 8th March, 58 on 9th March and 41 on 10th March. This compares to an average of 150 eruptions on normal days. When Semeru erupted on 6th March, the crater was showing low activity, with ash to a height of 50 m, in contrast to an eruption in May last 2008 when emissions reached 700 m above the crater. A lack of activity may indicate Semeru is pressurising prior to a large eruption. The Australian Bureau of Meteorology often requests the latest reports on Semeru because of concerns for the safety of flights to Australia, which pass over the volcano. Ash containing high silica could pose risk to flights if it enters plane engines.
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Saturday, March 07, 2009

Semeru Volcano, Indonesia - John Seach

Increased activity has been reported at Semeru volcano in Indonesia. Between 6th February and 4th March 2009 there were 873 explosion earthquakes registered, with an average of 34 events per day. On 5th March there was one period of tremor recorded. On 6th March one episode of tremor was recorded accompanied by booming sounds which were heard at Semeru observatory. On 6th March at 10:28 hr a booming noise was heard while the summit was covered in cloud. Semeru is at level 2 alert (Waspada) out of a maximum of 4. Explosions occur at an interval of 20-30 minutes, with ash emissions 100-400 m above Jonggring Seloko crater. So far the current eruptions have not been accompanied by pyroclastic flows, but this remains a danger. Areas which may be affected by pyroclastic flows include inhabited areas of Rowo Baung, Supit, Pronojiwo, Urip, and Umbulandi Urang Supit. Rowo Baung and Supit are the nearest villages to the eruptive centre, 9 km from the peak of Gunung Semeru. There is a potential threat to sand mining activities at Supit and Rowo Baung. Recommendations from the Indonesian Centre of Volcanology and Geology are that people avoid the area 4 km SE of the active crater due to the threat of pyroclastic flows. People are advised not to climb to the summit peak (Mahameru). Residents should prepare for possible ashfall. Aircraft should beware of explosion hazards, and ash emissions.
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