Saturday, October 31, 2009

Galeras Volcano, Colombia - John Seach

Since 27th October 2009 there has been a marked change in the activity at Galeras volcano in Colombia. There has been a significant decrease in emissions of sulphur dioxide and an increase in earthquakes associated with volcanic overpressure in the system. Galeras has been increased to level 2 alert.
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Mayon Volcano, Philippines - John Seach

The fourth typhoon to hit the Philippines in a month has forced the evacuation of 10,000 people from around Mayon volcano, due to the threat of lahars. Mayon is the most active volcano in the Philippines and has been erupting small amounts of ash this month. A large eruption in 2006 deposited lava and ash on the slopes of the volcano which may be mobilised after heavy rain.
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Thursday, October 29, 2009

Volcanoes and Climate Change - John Seach

Large volcanic eruptions can cause global climate change and even be responsible for mass extinctions.

Major eruptions in Kamchatka Peninsula, Russia have a disproportional effect on global climate, due to the low troposphere elevation at these latitudes, and the ease of dispersal of ash, aerosol, and gas.

Most mass extinctions during the last 500 million years coincide with eruptions of large igneous provinces. The Cretaceous-Tertiary extinction was synchronous with the Deccan flood volcanism.

There is a positive feedback between glacial variability and atmospheric CO2 concentrations: deglaciation increases volcanic eruptions, raises atmospheric
CO2, and causes more deglaciation. Conversely, waning volcanic activity during an interglacial could lead to a reduction in CO2 and the onset of an ice age.

The eruption of Tambora volcano in Indonesia (1815) caused a change in global temperatures. Following the eruption parts of Europe and North America experienced a wet and cold summer season (year without a summer).

The Huaynaputina eruption in Peru, 1600 (VEI 6) coincided with low tropical temperatures, which were 0.44 deg C colder than in the year following Tambora eruption in Indonesia (1816).

Large explosive volcanic eruptions recorded in the historical volcano record
and in polar ice cores over the past 5000 years have produced mid-latitude warm-season cooling with potential effects across the northern hemisphere or globe.

Supercontinent breakup is caused by two events - mantle plumes and global warming. The breakup of Pangea, the last supercontinent, was accompanied
by eruption of the largest known continental flood basalt, the Central Atlantic Magmatic Province, which caused massive extinctions at the Triassic-Jurassic boundary.

The eruption of Krakatoa volcano in 1883 cooled the global climate and caused a drop in sea level. Even though the oceans were gradually warming because of changes in Earth's climate, sea level didn't return to its pre-Krakatoa height until about 1950.

Mud volcanoes are a source of methane (CH4) flux to the atmosphere and the ocean.

Large volcanic eruptions cause a depletion of atmospheric ozone. This happened after the eruption of Pinatubo volcano, Philippines, in 1991. Global ozone was reduced by 5% compared to the 1964-1980 average.


Wednesday, October 28, 2009

Mayon Volcano, Philippines - John Seach

An ash emission occurred at Mayon volcano, Philippines at 05;32 hr on Wednesday 28th October 2009. The eruption lasted for one minute, and produced a brown ash plume which rose to a maximum height of 600 meters above the crater and drifted northeast. Over the past 24-hours, the seismic network recorded 13 volcanic earthquakes. There is a six-kilometer permanent danger zone and a seven-km extended danger zone around the volcano. Residents are advised to beware of lahars after heavy rain.
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Monday, October 26, 2009

Kilauea Volcano, Hawaii - John Seach

A lava flow crossed the former Kalapana road around 1:45 am on 23rd October, 2009, at Kilauea Volcano in Hawaii. The lava flow stopped moving by afternoon, but the road continued to burn, igniting trees in the surrounding kipuka. The lava flows remained active Saturday afternoon and were advancing in a southeast direction from the road in the kipuka between the 1989 Quarry flow, where a Public Viewing Area and trail was established.
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Sunday, October 25, 2009

Banda Sea Earthquake, Indonesia (Mag 7.0) - John Seach

On 24th October 2009 at 11:40 pm local time, a magnitude 7.0 earthquake hit 40 km NE of Serua volcano, and 70 km south of Manuk volcano, Indonesia. The earthquake epicentre was located undersea at 6.161°S, 130.346°E, and focus was at a depth of 138 km. No tsunami was generated. Serua volcano last erupted in 1921.
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Saturday, October 24, 2009

Sumbing volcano, Sumatra, Indonesia - John Seach

In late October 2009 wildlife rangers on the western slope of Sumbing volcano, Sumatra, Indonesia felt earthquakes, and observed new solfatara, and areas of burnt vegetation.
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Soufriere Hills Volcano, Montserrat - John Seach

Seismic activity has been high at Soufriere Hills volcano, Montserrat during the week 16-23 October 2009. One thousand and nineteen rockfall signals, four hundred and sixteen long period events and four volcano-tectonic earthquakes were recorded during the week. Pyroclastic flows occurred down the White River valley to the south and several have reached the sea. Small pyroclastic flows are still occurring in Tuitts Ghaut on the northeast, Gages valley to the west and rarely in Tyers Ghaut. These pyroclastic flows extended less than 2 km. The lava dome is continuing to grow mainly to the south and southeast. Average sulphur dioxide measurements were 465 tons per day, with a range of 261 to 652 tons per day. Heavy rainfall caused lahars in the Belham valley. The Hazard Level is 3 (on an increasing scale from 1-5).
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Wednesday, October 21, 2009

Kaba Volcano, Indonesia - John Seach

Seismic activity has increased at Kaba volcano, Sumatra, Indonesia. On 19th October 2009, 127 shallow volcanic earthquakes were recorded. Continuous tremor occurred on 19th October between 06:40-09:00 hr, and 20th October between 03:00 to 09:00 hr. Visual observations showed thin white emissions rising 50 m above the crater. Ground deformation has been measured across the volcano. Water temperature measurements of the craters on 15th October was 72 deg C, with a degree of acidity (pH) 3.2. Solfatara temperatures range from 106 to 107 deg C. A one kilometre exclusion zone has been placed around the crater. On 20th October the volcano was raised to alert level 2.
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Sunday, October 18, 2009

Piton de la Fournaise Volcano, Reunion - John Seach

The frequency and intensity of seismicity are gradually increasing at Piton de la Fournaise volcano on Reunion. The trend of gradual deformation of the volcano continues, particularly on the north side of Dolomieu and near Soufriere. On Friday 16th October the seismic network recorded one earthquake every seventy seconds, with a maximum magnitude of 3. This is a remarkable intensity for Piton de la Fournaise volcano where earthquakes rarely exceed magnitude 2. The earthquakes are currently located at a depth of 2000 m, which indicates magma has not yet reached the surface. The pre-eruptive pattern of Piton de la Fournaise volcano is marked by several seismic crises, punctuated by periods of rest. There has been no change in the chemical composition of gas at the volcano. Alert level 1 (eruption imminent or likely) remains since 7th October after the first seismic crisis, and access to the volcano summit is prohibited.
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Soufriere Hills Volcano, Montserrat - John Seach

During the week 9-16 October 2009 activity has been high at Soufriere Hills volcano, Montserrat. A new lava dome has been growing at the volcano since 9th October 2009. Seismic activity during the week consisted of 1224 rockfall signals, 382 long period events, and one volcano tectonic earthquake. Pyroclastic flows occurred in all the major valleys that drain the volcano except the Tar River valley. Pyroclastic flows began on 9-10 October and extended south of the volcano. From 11 October pyroclastic flows extended down the Tyers Ghaut. Pyroclastic flows have reached about 3 km down the White River to the south; 1.5 km down the Gages valley to the west; and 3 km down Tuitts and Whites Bottom Ghaut in the east. Dome growth is located at the volcano summit which is responsible for the radial flow of pyroclastic flows. Lahars occurred in Belham valley on 14th October.
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Saturday, October 17, 2009

Gaua Volcano, Vanuatu - John Seach

An assessment of Gaua volcano was made by staff from Vanuatu Geohazards Observatory from 3-7 October 2009. The survey confirmed an eruptive phase began at Gaua from the 27th of September 2009. Volcanic gas measurements on 3rd October show that 3000 tons of sulphur dioxide was released from Gaua volcano daily. The alert level has been raised to 2 (on a scale of 0-4). People are advised to stay away from the summit area.
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Krakatau Volcano, Indonesia - John Seach

A large earthquake (magnitude 6.1) hit 60 km SSW of Krakatau volcano Indonesia. The earthquake's focus was at a depth of 50 km and located in the Sunda Strait under Panaitan Island. Krakatau volcano has been erupting in 2009. The earthquake is related to the Sunda subduction zone. The earthquake was felt with an intensity of III-IV at Krakatau Volcano Observatory. According to the results recorded at Gunungapi Seismometer Krakatoa in Pasauran, the earthquake hit at 16:53:06 pm, and had a duration of 601 seconds, with a maximum amplitude of 70 mm and aftershocks at 17:01:24 had a duration of 171 seconds with a maximum amplitude of 69 mm. At Gede volcano observation post the earthquake was felt with an intensity of III, and had a duration of 300 seconds. People have been advised to stay alert to the occurrence of aftershocks, where the energy is usually smaller than the main earthquake. The earthquake did not cause a tsunami, because although the earthquake was centered in the ocean, its depth over 50 km and magnitude was not large enough to produce a deformation of the ocean floor.
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Friday, October 16, 2009

Piton de la Fournaise Volcano, Reunion - John Seach

A seismic crisis began at Piton de la Fournaise volcano, Reunion Island on Wednesday 14th October 2009. The swarm generated 338 earthquakes with a maximum magnitude of 2.3. The trend of gradual deformation continues, with about 1.5 cm of displacement in two weeks. No change in gas chemistry has been detected. Data analysis suggests the process of magmatic intrusion continues at depth. This significant seismicity has been associated with small deformation of the northern flank of Dolomieu. Small avalanches have occurred inside Dolomieu, particularly towards the end of the seismic crisis. Alert Level 1 remains in place. Public access to the volcano summit, and helicopter landing on the volcano are prohibited.
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Sunday, October 11, 2009

Chaiten Volcano, Chile - John Seach

A flyover of Chaiten volcano on 29th September 2009 showed the volcano continues to erupt. There has been a change in morphology which reflects changing conditions at the summit dome complex. A third dome is forming in the centre west of the crater. During the observation period of 16-30 September 2009 ash emissions reached a height of 2 km above the summit. The two major sources of emissions are in the centre and east of the dome complex. Block and ash flows are occurring, indicating that the dome complex is very active and has continued to grow. On 29th September information was received about the possible reactivation of Chaiten volcano. The information corresponded to visual observations made by people from the town of Chaitén, which reported an increase in eruptive activity just after 14:00 hrs. The increase in activity related to gravitational collapse of a dome in the southwest followed by an increase in emissions of gas and ash. Seismic data indicated the partial dome collapse corresponded to arrival of low frequency and large amplitude signals produced by the great Samoan earthquake. The event caused changes to the unstable part of Chaiten's dome complex, but little other change to other parts of the volcano. There have been previous examples in the literature of distant earthquakes causing a change in eruptive activity at volcanoes.
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Thursday, October 08, 2009

Vanuatu/Solomon Islands Earthquakes, 8th October 2009 - John Seach

Listed below is a summary of the large and major earthquakes to hit the Vanuatu/Solomon Islands region today, 8th October 2009. Times are local.
Mag 6.1 8th October 2009 at 07:34 pm. 12.284°S, 166.568°E. Depth 35 km.
Mag 7.0 8th October 2009 at 07:28 pm. 13.298°S, 165.951°E. Depth 35 km.
Mag 6.6 8th October 2009 at 01:12 pm. 11.650°S, 166.170°E. Depth 35 km.
Mag 7.3 8th October 2009 at 10:13 am. 13.145°S, 166.297°E. Depth 33 km.
Mag 7.7 8th October 2009 at 09:18 am. 12.554°S, 166.320°E. Depth 35 km.
Mag 7.8 8th October 2009 at 09:03 am. 13.052°S, 166.187°E. Depth 35 km.
Earthquakes of this size can disrupt nearby volcanoes. Active Vanuatu volcanoes close to the epicentre are Suretamatai, Gaua, Ambae, Ambrym, and Lopevi. Tinakula volcano is located north in the Solomon Islands.
Volcanoes of Vanuatu...

Vanuatu Earthquakes and Tsunami 8th October 2009 - John Seach

Three major earthquakes hit northern Vanuatu this morning (8th October 2009). The first earthquake hit at 9:03 am local time 37 km west of the Torres Islands. This was followed at 9:18 am by magnitude 7.7 earthquake, and 10:13 am by magnitude 7.3 earthquake. A small tsunami was generated. Earthquakes of this size can affect nearby volcanoes. Active Vanuatu volcanoes close to the epicentre are Suretamatai, Gaua, Ambae, Ambrym, and Lopevi. Tinakula volcano is located north in the Solomon Islands. Gaua volcano in northern Vanuatu has been showing signs of increasing activity over the last week.
Volcanoes of Vanuatu...

Tuesday, October 06, 2009

Soufriere Hills Volcano, Montserrat - John Seach

Renewed eruptions occurred at Soufriere Hills volcano on Montserrat on 5th October. A swarm of earthquakes began at 9pm on 4th October. Two hours of vigorous ash emission began at 10 pm on 5th October. The eruptions were followed by intermittent ash emissions. This was the first eruptions at the volcano since April 2009.
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Thursday, October 01, 2009

Gaua Volcano, Vanuatu - John Seach

Gaua volcano in Vanuatu is showing signs of unrest. During the past few days the volcano has emitted large quantity of "smoke". People on the island have noticed a strong sulphur smell. Residents have been advised to stay away from Mt Garet cone. An eruption of Gaua volcano in 1973 forced the temporary evacuation of the island.
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Indonesia Earthquake (magnitude 6.8) - John Seach

A magnitude 6.8 earthquake occurred 17km SW of the summit of Sumbing volcano, Sumatra, Indonesia, on 1st October 2009. The volcano last erupted in 1730. Other volcanoes near the earthquake epicentre include Hutapanjang and Kunyit. This follows a magnitude 7.6 earthquake which hit Sumatra 200 km northwest yesterday.
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Galeras Volcano, Colombia - John Seach

An explosive eruption occurred at Galeras volcano, Colombia at 9:14 am on 30th September 2009. The eruption was accompanied by acoustic waves. National Parks staff at the western rim of the volcano reported two explosions with the ejection of incandescent material at the active cone. An ash column reached a height of 8-11 km above the summit. Sulphur dioxide measurements made between 9:30 and 10:00 am showed high levels between 1100 and 9300 tons/day. Ashfall was reported in the Municipalities of Sandona, Ancuya, Linares, La Llanada, and Sotomayor. The eruptive event was similar in size to that of 20th February 2009. After the eruption seismicity decreased. Due to the presence of magma close to the surface, and the history of the volcano, INGEOMINAS has raised the alert status to the highest level RED.
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