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June 22nd 2009
Indonesia/Lombok - Rinjani Volcano
Ongoing Volcanic Activity
Based on analysis of satellite imagery, the Darwin VAAC reported that during 21 June ash plumes from Rinjani rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 55 km N.
Geologic Summary: Rinjani volcano on the island of Lombok rises to 3,726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the E, but the W side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak caldera. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the E end of the caldera. Historical eruptions at Rinjani dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.


June 17th 2009
Indonesia/Lombok - Rinjani Volcano
Volcanic Activity
Base on analysis of satellite imagery, the Darwin VAAC reported that during 11-12 and 16 June ash plumes from Rinjani rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted 15-55 km W and WSW.
Geologic Summary: Rinjani volcano on the island of Lombok rises to 3,726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the E, but the W side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak caldera. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the E end of the caldera. Historical eruptions at Rinjani dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.


June 6th 2009
Indonesia - Sangeang Volcano
Volcanic Activity
There has been an increase in activity at Sangeang volcano in Indonesia, with increasing numbers of volcanic earthquakes and tremor. White emissions are visible rising 25 m above the summit. The alert status of Sangeang Api Volcano has been raised from normal to Waspada (Level II).
Geologic Summary: Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, 1949-m-high Doro Api and 1795-m-high Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century.


June 1st 2009
Indonesia - Karangetang Volcano
Volcanic Activity
An eruption occurred at Karangetang volcano, Indonesia on 31st May. Hundreds of people have been evacuated from near the volcano, due to fears of pyroclastic flows. The volcano is located at the northern end of Siau island, north of Sulawesi.
Geologic Summary: Karangetang (also known as Api Siau) lies at the northern end of the island of Siau, N of Sulawesi, and contains five summit craters strung along a N-S line. One of Indonesia's most active volcanoes, Karangetang has had more than 40 recorded eruptions since 1675. Twentieth-century eruptions have included frequent explosions, sometimes accompanied by pyroclastic flows and lahars.


May 21st 2009
Saudi Arabia - Harrat Lunayyir Volcano
Activity
A series of earthquakes occurred near Harrat Lunayyir volcano in north east Saudi Arabia on Tuesday 19th May 2009. The largest earthquake measured magnitude 5.7. The earthquakes produced cracks in the ground. A total of 2,289 people, including 326 families, were evacuated from a 20 km radius around the volcano, 240 km north of Madinah. Evacuees were housed in Yanbu. The evacuations took place as 30 earthquakes were recorded between 3 and 5.4 on the Richter scale. Local authorities have announced the closure of schools for two weeks starting Saturday in Umlaj.
Geologic Summary: Harrat Lunayyir is a basaltic volcanic field in NW Saudi Arabia, east of the Red Sea port of Umm Lajj. It contains about 50 volcanic cones that were constructed over Precambrian crystalline rocks along a N-S axis. Harrat Lunayyir is one of the smallest of the Holocene lava fields of Saudi Arabia, but individual flow lobes radiate long distances from the center of the Harrat, and flows reached the Red Sea in two places. Lava flows are basaltic to basanitic in composition, and the Holocene flows are alkali olivine basalts. One of the cones may have erupted around the 10th century AD or earlier.


May 8th 2009
Chile - Chaitén Volcano
Volcanic Activity
Dome growth continues in the summit crater at Chaiten volcano, Chile. The surface morphology of the dome is complex and uneven. The central pinnacle of the dome has broken into three main blocks. The tallest spine is 100 m high. Continuing rapid growth of the dome creates a collapse risk with the subsequent hazard of block and ash flow down the Chaiten River valley. Seismic activity remains high at the volcano. Chaiten volcano remains on the highest alert level - RED.
Geologic Summary: Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m.


May 6th 2009
Indonesia - Krakatau Volcano
Volcanic Activity
Eruptions are continuing at Krakatau volcano in Indonesia from a crater on the SW side of the cone. A volcanic ash advisory from Darwin VAAC reported ash to 10,000 drifting NW of the volcano. Today the level of alert at Krakatau was raised from Waspada (Level 2) to Siaga (Level 3), out of a maximum level 4. A renewed period of eruptions began at Krakatau on 19th March 2009, when 19 explosions were recorded. Between 1-25 April 2009 there have been 4060 explosions. Number of explosion earthquakes measured are 30 April 229, 1 May 324, 2 May 318, 3 May 250, 4 May 403, 5 May 371, and 6 May 132 (until midday). Shallow volcanic earthquakes, and tremor have been recorded. Visual observations from Rajabasa District in Sumatra in April reported ash emissions from 50-1000 m above the summit. From 1-24 April booming noises were heard from Sumatra 174 times, 83 times from 25-29 April. No sounds were heard between 30th April and 6th May. Incandescent material and ash are being emitted to a radius of 500 m from the crater. Pyroclastic flows may reach a distance of 700 m from the crater. Ash is falling 5 km from the volcano. Requests from the Indonesian Directorate of Volcanology and Geological Hazard Mitigation request people stay at least 2 km from the volcano. Local communities are still allowed to fish outside the 2 km danger zone radius. Communities in the coastal province of Banten and Lampung are requested to remain calm and not fear a tsunami.
Geologic Summary: The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.


May 2nd 2009
Indonesia/Lombok - Rinjani Volcano
Volcanic Activity
An increase in seismic activity has been reported at Rinjani volcano on the island of Lombok. On 2nd May there were three explosion earthquakes recorded. A white plume was emitted 1000 m above the eruption point. The alert level at the volcano has been raised from Normal (Level I) to Waspada (Level II). The summit has been closed to climbers. Residents need to beware of lahars.
Geologic Summary: Rinjani volcano on the island of Lombok rises to 3726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the east, but the west side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak caldera. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the east end of the caldera. Historical eruptions at Rinjani dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.


April 25th 2009
Chile - Chaitén Volcano
Volcanic activity
Seismic activity at Chaiten volcano in Chile remains high, with earthquakes reaching a maximum magnitude 4.5. Dome growth continues in the summit crater. Ash emissions rose to a height of 1.5 km above the crater. During the week of 15-21 April, there were only two days where the summit was cloud free. The volcano remains on the highest alert level - RED.
Geologic Summary: Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m.


April 24th 2009
Indonesia - Slamet Volcano
Volcanic Eruption
Slamet volcano in Indonesia has begun erupting this week. The number of explosion earthquakes detected were 49 on 19th April, 97 on 20th April, 163 on 22nd April, and 52 yesterday. Emissions were visible rising 800 m above the summit. Slamet volcano was raised to level 3 alert (Siaga), and the summit has been closed to climbers.
Geologic Summary: Slamet volcano, Java's second highest volcano at 3428 m and one of its most active, has a cluster of about three dozen cinder cones on its lower SE-NE flanks and a single cinder cone on the western flank. Slamet is composed of two overlapping edifices, an older basaltic-andesite to andesitic volcano on the west and a younger basaltic to basaltic-andesite one on the east. Gunung Malang II cinder cone on the upper eastern flank on the younger edifice fed a lava flow that extends 6 km to the east. Four craters occur at the summit of Gunung Slamet, with activity migrating to the SW over time.


April 21st 2009
Indonesia - Slamet Volcano
Volcanic Activity
An increased number of earthquakes have been recorded at Slamet volcano in Indonesia. Brown plumes were observed rising 50 m above the summit. The summit area has been closed to climbers. Today, Slamet volcano was raised to level 2 alert (Waspada).
Geologic Summary: Slamet volcano, Java's second highest volcano at 3428 m and one of its most active, has a cluster of about three dozen cinder cones on its lower SE-NE flanks and a single cinder cone on the western flank. Slamet is composed of two overlapping edifices, an older basaltic-andesite to andesitic volcano on the west and a younger basaltic to basaltic-andesite one on the east. Gunung Malang II cinder cone on the upper eastern flank on the younger edifice fed a lava flow that extends 6 km to the east. Four craters occur at the summit of Gunung Slamet, with activity migrating to the SW over time.


April 14th 2009
Chile - Chaitén Volcano
Volcanic Activity
Seismic activity has increased at Chaiten volcano since 8th April 2009. The trend increased further from 11-12 April with earthquakes up to magnitude 4.5 recorded. The increased number of earthquakes is associated with growth of the summit lava dome. Dome collapse remains a hazard, and may generate ash and block flows which can affect the valleys below the summit. The volcano remain on the highest level of alert - RED.
Geologic Summary: Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m.


April 12th 2009
Galapagos Islands - Fernandina Volcano
Volcanic Eruption
A new eruption began at Fernandina volcano. The seismic station at Puerto Ayora did not record any earthquakes associated with the eruption. The eruption was observed by rangers from Galapagos National Park, and a tourist boat in the early hours of Saturday morning (local time). An eruption column with low ash content was visible on satellite images extending 300 km west of the volcano. Satellite images show several hotspots at Fernandina volcano, which may indicate lava flows. Personnel from the Galapagos National Park on Isabela Island are making a flight over the volcano, to ascertain more precisely the location of the eruption centre, and assess the extent of the lava flows and their likely impact to the fauna and flora of the area. The last eruption of Fernandina volcano occurred in 2005, when lava flows originated from a fissure on the south-eastern flank of the volcano and descend without reaching the sea.
Geologic Summary: Fernandina, the most active of Galápagos volcanoes and the one closest to the Galápagos mantle plume, is a basaltic shield volcano with a deep 5 x 6.5 km summit caldera. The volcano displays the classic "overturned soup bowl" profile of Galápagos shield volcanoes. Its caldera is elongated in a NW-SE direction and formed during several episodes of collapse. Circumferential fissures surround the caldera and were instrumental in growth of the volcano. Reporting has been poor in this uninhabited western end of the archipelago, and even a 1981 eruption was not witnessed at the time. In 1968 the caldera floor dropped 350 m following a major explosive eruption. Subsequent eruptions, mostly from vents located on or near the caldera boundary faults, have produced lava flows inside the caldera as well as those in 1995 that reached the coast from a SW-flank vent. Collapse of a nearly 1 cu km section of the east caldera wall during an eruption in 1988 produced a debris-avalanche deposit that covered much of the caldera floor and absorbed the caldera lake.


April 8th 2009
Chile - Llaima Volcano
Volcanic Eruption
Eruptions continue at Llaima volcano in Chile. The volcano has been covered in cloud and continuous eruption have been detected. Ashfall was reported east of the volcano and seismicity has remained constant.
Geologic Summary: Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other, Pichillaima, to the SE. The massive 3125-m-high, dominantly basaltic-to-andesitic stratovolcano has a volume of 400 cu km. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following the eruption of the 24 cu km Curacautín Ignimbrite.


April 4th 2009
Chile - Llaima Volcano
Volcanic Eruption
Llaima volcano in Chile erupted yesterday (April 3rd 2009) after several months of low seismic activity. On 2nd April at 16:00 hrs (local time) there was an increase in amplitude and frequency of long period earthquakes reaching 45 to 60 per hour. This increase in seismicity remained constant until 18:00 hrs on 3rd April, and then evolved to a continuous seismic tremor of low frequency. The slight increase in seismic activity recorded on 2-3 April was associated with weak emissions of vapour. From 20:30 hrs on 3rd April, eyewitnesses reported a glow in the main crater. At 21:00 hrs, the tremor increased, while at 22:45 hrs weak strombolian explosions occurred in the main crater. Until 06:00 hrs on 4th April, moderate strombolian eruptions occurred every 1-3 seconds, from two cones in the crater. Incandescent material was ejected 700 m above the crater. Muddy water has been reported in rivers draining the volcano. Melting of snow and ice from the eruption is creating a lahar hazard. Twelve people have been evacuated from Conguillio national park, which has been closed.
Geologic Summary: Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other, Pichillaima, to the SE. The massive 3125-m-high, dominantly basaltic-to-andesitic stratovolcano has a volume of 400 cu km. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following the eruption of the 24 cu km Curacautín Ignimbrite.


April 4th 2009
Papua New Guinea - Rabaul Volcano
Volcanic Activity
Eruptions continue at Rabaul volcano in Papua New Guinea. During the week of 27th March to 2nd April there were occasional strong ash emissions from Tavurvur crater, accompanied by roaring noises. A crater glow was visible at night. Ash fell over Rabaul town on 2nd April, and drifted SE on other days. Generally, deflation was measured at the caldera, but there were periods of inflation during the past 2 weeks. People are advised to stay at least 2 km from the volcano due to risks from explosive activity.
Geologic Summary: The low-lying Rabaul caldera forms a sheltered harbor once utilized by New Britain's largest city. A powerful explosive eruption in 1994 forced its abandonment. The 8 x 14 km caldera is widely breached on the east, where its floor is flooded by Blanche Bay. Two major Holocene caldera-forming eruptions took place as recently as 3500 and 1400 years ago. Several post-caldera cones, including Tavurvur, the bare cone on the right horizon, have erupted during historical time.


March 30th 2009
Indonesia - Krakatau Volcano
Volcanic Activity
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.
Geologic Summary: The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.


March 18th 2009
Tonga - Hunga Tonga and Hunga Ha'apai Volcano
Undersea Eruption
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.
Geologic Summary: The small islands of Hunga Tonga and Hunga Ha'apai cap a large seamount located about 30 km SSE of Falcon Island. The two linear andesitic islands are about 2 km long and represent the western and northern remnants of a the rim of a largely submarine caldera lying east and south of the islands. Hunga Tonga and Hunga Ha'apai reach an elevation of only 149 m and 128 m above sea level, respectively, and display inward-facing sea cliffs with lava and tephra layers dipping gently away from the submarine caldera. A rocky shoal 3.2 km SE of Hunga Ha'apai and 3 km south of Hunga Tonga marks the most prominent historically active vent. Submarine eruptions were reported here in 1912 and 1937 and from a fissure 1 km SSE of Hunga Ha'apai in 1988.


March 14th 2009
Colombia - Galeras Volcano
Volcanic Eruption
Galeras volcano in Colombia erupted yesterday 13th March forcing the evacuation of 3000 people. The explosive eruption occurred at 3:55 pm local time 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 20th February 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.
Geologic Summary: Galeras, a stratovolcano with a large breached caldera located immediately west of the city of Pasto, is one of Colombia's most frequently active volcanoes. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.


March 7th 2009
Indonesia/Java - Semeru Volcano
Volcanic Activity
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.
Geologic Summary: Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises abruptly to 3676 m above coastal plains to the south. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano. Semeru has been in almost continuous eruption since 1967.


February 22nd 2009
Colombia - Galeras Volcano
Volcanic Eruption
Last Friday (20.02.2009), an eruption occurred at Galeras volcano at 7:05 am, local time. The eruption was accompanied by shock waves, and vibrations in several villages located in the catchment area of the volcano. There were at least two explosions, and emission of incandescent material, along with a sulphurous smell. The initial eruptive event was associated with a seismic signal which lasted for approximately 13 minutes. Wind direction according to the weather station installed at the top of Galeras, is toward the west coast. There are reports of ash fall in areas of the municipalities of Sandona, Consacá and Ancuya, located on the western flank of Galeras. The eruptive column showed three levels of dispersion. The column reached a height of about 8 km, with dispersal to the east, at an altitude of 2.500 m, the plume of ash was to the west, and between these two levels, the ash moved north. This dispersion was due to variable wind conditions at different altitudes. After the eruption there was a decrease in seismic activity, characterized by the presence of a few events associated with fluid dynamics and low energy levels. Due to the presence of magmatic material at the surface and taking into account the evolution of the current activity, it is possible for new eruptive episodes. The volcanic warning level at Galeras was raised from III/Yellow; "changes in the behavior of volcanic activity") to I/Red; "imminent eruption or in progress". According to news articles, authorities ordered the evacuation of about 8,000 people living on the slopes, but few went to evacuation shelters.
Geologic Summary: Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Longterm extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.


February 20th 2009
Chile - Chaiten Volcano
Volcanic Eruption
Yesterday, an explosive eruption occurred at Chaiten volcano. A flyover of the volcano revealed a fracture in the lava dome, which had partially collapsed. Large quantities of gases and pyroclastic material were observed. About 160 residents were evacuated from Chaiten town, 10 km from the volcano. Most of the residents of Chaiten town evacuated last year after large eruptions in May. The volcano has been in continuous eruption since May 2008, and periodic larger explosions create a hazard for residents remaining in the area.
Geologic Summary: Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m.


February 4th 2009
Alaska - Redoubt Volcano
Volcanic Activity
Seismicity remains elevated at Redoubt Volcano in Alaska. Melting of the glacier has produced a 200 m wide hole, which is emitting gas. The Federal Aviation Administration has issued a temporary flight restriction for a 10-mile radius around Redoubt, from ground level to 60,000 feet. During the last eruption in 1989, an aircraft flew through a plume of ash. All four engines ingested ash and flamed out. The crew successfully restarted the engines and landed safely at Anchorage. All four engines were replaced.
Geologic Summary: Redoubt is a 3108-m-high glacier-covered stratovolcano with a breached summit crater in Lake Clark National Park about 170 km SW of Anchorage. Next to Mount Spurr, Redoubt has been the most active Holocene volcano in the upper Cook Inlet. The volcano was constructed beginning about 890,000 years ago over Mesozoic granitic rocks of the Alaska-Aleutian Range batholith. Collapse of the summit of Redoubt 10,500-13,000 years ago produced a major debris avalanche that reached Cook Inlet. Holocene activity has included the emplacement of a large debris avalanche and clay-rich lahars that dammed Lake Crescent on the south side and reached Cook Inlet about 3500 years ago. Eruptions during the past few centuries have affected only the Drift River drainage on the north. Historical eruptions have originated from a vent at the north end of the 1.8-km-wide breached summit crater. The 1989-90 eruption of Redoubt had severe economic impact on the Cook Inlet region and affected air traffic far beyond the volcano.


February 2nd 2009
Japan - Asama Volcano
Volcanic Eruption
Asama volcano in Japan erupted today at 1:51 am, local time, sending ash to a height of 1.6 km, and ejecting rocks 1 km from the crater. Ashfall was reported in Tokyo, 140 km SE of the volcano.
Geologic Summary: Asama, Honshu's most active volcano, overlooks the resort town of Karuizawa, 140 km NW of Tokyo. The volcano is located at the junction of the Izu-Marianas and NE Japan volcanic arcs. The modern cone of Maekake-yama forms the summit of the volcano and is situated east of the horseshoe-shaped remnant of an older andesitic volcano, Kurofu-yama, which was destroyed by a late-Pleistocene landslide about 20,000 years before present (BP). Growth of a dacitic shield volcano was accompanied by pumiceous pyroclastic flows, the largest of which occurred about 14,000-11,000 years BP, and by growth of the Ko-Asama-yama lava dome on the east flank. Maekake-yama, capped by the Kama-yama pyroclastic cone that forms the present summit of the volcano, is probably only a few thousand years old and has an historical record dating back at least to the 11th century AD. Maekake-yama has had several major plinian eruptions, the last two of which occurred in 1108 (Asama's largest Holocene eruption) and 1783 AD.


January 30th 2009
Chile - Chaiten Volcano
Volcanic Activity
Seismicity associated with the eruption of Chaitén volcano in Chile has decreased over the past week. Viscous lava is still being erupted into the dome, but this is occurring at a reduced rate. Dome collapse is still a danger, with pyroclastic flows potentially traveling down flanks of the volcano and valleys. On 19th of January there was a collapse of spines of the dome, with block and ash moving down the eastern and southeastern flank. During an overflight on 21st January the prominent spines were no longer present on the lava dome. Several steep landslides were visible on the eastern side of the dome. Thermal imaging shows many hotspots on the dome. The volcano is still at alert level RED due to the ongoing eruptions.
Geologic Summary: Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m.


January 23rd 2009
Indonesia - Wurlali Volcano
Earthquake
A magnitude 6.2 earthquake hit Wurlali volcano today at 5:16 am, local time. The earthquake epicentre was located 7 km south of Damar Island, and the focus was at 141 km depth. Wurlali Volcano is located on Damar Island, Indonesia, 375 km NE of Dili, East Timor.
Geologic Summary: Wurlali volcano (also known as Damar) is part of Indoneisia's Banda Island chain. The 868-m-high stratovolcano was formed in the northern part of a 5-km-wide caldera, and has twin summit craters. During historical time only a single explosive eruption occurred, in 1892 from the summit crater.


January 16th 2009
Indonesia/Java - Dieng Plateau
Volcanic activity
Yesterday, Dieng volcano on Java in Indonesia has been raised from level I to II alert (out of maximum 4) after two phreatic eruptions. The eruptions occurred at Sibanteng crater at 0800 and 0830 hr local time. Material was ejected 50 m from the crater. There has not been any increase in toxic gas at the volcano.
It is recommended that residents and tourists stay more than 300 m away from the craters.
Geologic Summary: The Dieng plateau in the highlands of central Java is renowned both for the variety of its volcanic scenery and as a sacred area housing Java's oldest Hindu temples, dating back to the 9th century AD. The Dieng volcanic complex consists of two or more stratovolcanoes and more than 20 small craters and cones of Pleistocene-to-Holocene age over a 6 x 14 km area. Prahu stratovolcano was truncated by a large Pleistocene caldera, which was subsequently filled by a series of dissected to youthful cones, lava domes, and craters, many containing lakes. Lava flows cover much of the plateau, but have not occurred in historical time, when activity has been restricted to minor phreatic eruptions. Toxic volcanic gas emission has caused fatalities and is a hazard at several craters. The abundant thermal features that dot the plateau and high heat flow make Dieng a major geothermal prospect.


January 10th 2009
Rabaul Volcano, Papua New Guinea
Volcanic Activity
Ash emissions from Rabaul volcano in Papua New Guinea closed Tokua airport between Monday and Friday this week. Hundreds of people have not been able to leave, or fly into East New Britain province. A north-west wind is pushing plumes towards Tokua airport 20 kilometres away. Some incandescent lava fragments were emitted from Tarvurvur cone. Most of the lava fragments fell back into the crater but some fell on the slopes of the volcano. A local shipping company has offered to take up to 400 passengers to an airport in nearby New Ireland Province, which is not affected by the volcano. Moderate level seismicity accompanied the eruptions. An earthquake occurred at about 07:47 a.m. yesterday (magnitude 5.6), and was located about 135 km southeast from Rabaul at a depth of about 40 km. The earthquake was tectonic in origin. People are advised to stay more than 2 km away from Turvurvur cone due to ongoing explosive activity.


January 9th 2009
Poas Volcano, Costa Rica
Earthquake
A large earthquake (mag 6.1) occurred at Poas volcano on Thursday 8th January 2009. The epicentre was located 8 km east of the volcano summit. This was the largest earthquake to hit costa Rica in 150 years. Four people were killed by the earthquake. Poás is one of Costa Rica's most active volcanoes. The volcano is located within the Poas Volcano National Park.

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