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SI/USGS Weekly Volcanic Activity Report 14-20 April 2010
From: Ed Venzkee VENZKEE@xxxxxx
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SI/USGS Weekly Volcanic Activity Report
14-20 April 2010
Sally Kuhn Sennert - Weekly Report Editor
New Activity/Unrest: | Barren Island, Andaman Is | Eyjafjallajökull, Southern Iceland | Gaua, Banks Islands (SW Pacific)
Ongoing Activity: | Bezymianny, Central Kamchatka (Russia) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat
The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.
New Activity/Unrest
BARREN ISLAND Andaman Is 12.278°N, 93.858°E; summit elev. 354 m
Based on analysis of satellite imagery, the Darwin VAAC<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> reported that a plume from Barren Island rose to an altitude of 2.4 km (8,000 ft) a.s.l.<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> and drifting 55 km N on 19 April. However, ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> could not be identified from the satellite data.
Geologic Summary. Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit of volcano that rises from a depth of about 2,250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera<http://volcanoes.usgs.gov/images/pglossary/caldera.php> with walls 250-350 m high. The caldera, which is open to the sea on the W, was created during a major explosive eruption in the late Pleistocene<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> that produced pyroclastic-flow and -surge deposits. The morphology of a fresh pyroclastic cone that was constructed in the center of the caldera has varied during the course of historical<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> eruptions. Lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> flows fill much of the caldera floor and have reached the sea along the western coast during historical eruptions.
Source: Volcanic Ash Advisory Centre (VAAC)<http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html>
Barren Island Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=0600-01=> from the Global Volcanism Program
EYJAFJALLAJOKULL Southern Iceland 63.63°N, 19.62°W; summit elev. 1666 m
The Institute of Earth Sciences at the Nordic Volcanological Center (NVC) reported that a new set of craters opened in the early morning of 14 April under the ice-covered central summit caldera<http://volcanoes.usgs.gov/images/pglossary/caldera.php> of Eyjafjallajökull. This eruptive phase was preceded by a swarm of earthquakes and the onset of tremor. Aerial observations revealed a series of vents along a 2-km-long N-S fissure, with meltwater flowing down both the N and S slopes of the volcano. An ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> plume rose to more than 8 km altitude, and was deflected to the E by winds. Jokulhlaups (floods of meltwater) reached the lowlands around the volcano with peak flow around noon, damaging roads, infrastructure, and farmlands. There were no fatalities due to previous evacuations. Tephra-fall was reported in SE Iceland. A second jokulhlaup/lahar traveled down the Markarfljot valley that evening.
On 15 April the eruption plume reached mainland Europe, causing the closure of large areas of airspace. Activity continued during 16 April at a similar level as the previous day, with ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> generation and pulses of meltwater causing jokulhlaup/lahars in the evening. The next day there was some variability in seismic tremor and tephra<http://volcanoes.usgs.gov/images/pglossary/tephra.php> generation, but overall the activity remained stable. A pulsating eruptive column reached above 8 km altitude, and lightning was frequently seen within the plume.
Over the first 72 hours of explosive activity, scientists estimated that the eruption had produced 140 million cubic meters of tephra. An update from NVC on 21 April noted that activity had declined in the previous few days by an order of magnitude, though phreatomagmatic explosions were still occurring, sending plumes about 3 km high. Lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> spattering was seen at the craters, and meltwater flows were minor. Seismicity was not decreasing at that time, and samples collected on 19 April were of the same intermediate composition (58% SiO2) as early in the explosive phase, but with more fluorine.
The ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> cloud resulted in the cancellation of tens of thousands of daily flights, both into and out of major European cities, after 15 April. Although on 19 April the plume was only rising 1 km above the summit, it was ascending to altitudes of 5-7 km (15-20,000 ft) as it drifted to the S. Beginning on 20 April, after a decrease in activity and a significant dissipation of the plume, many previously closed areas were at least partially opened for limited service.
Geologic Summary. Eyjafjallajökull (also known as Eyjafjöll) is located west of Katla volcano. Eyjafjallajökull consists of an E-W-trending, elongated ice-covered basaltic-andesite stratovolcano<http://volcanoes.usgs.gov/images/pglossary/stratovolcano.php> with a 2.5-km-wide summit caldera. Fissure-fed lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> flows occur on both the eastern and western flanks of the volcano, but are more prominent on the western side. Although the 1666-m-high volcano has erupted during historical<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> time, it has been less active than other volcanoes of Iceland's eastern volcanic zone, and relatively few Holocene<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> lava flows are known. An intrusion beneath the south flank from July-December 1999 was accompanied by increased seismic activity and was constrained by tilt measurements, GPS-geodesy and InSAR. The last historical eruption of Eyjafjallajökull prior to an eruption in 2010 produced intermediate-to-silicic tephra<http://volcanoes.usgs.gov/images/pglossary/tephra.php> from the central caldera<http://volcanoes.usgs.gov/images/pglossary/caldera.php> during December 1821 to January 1823.
Sources: Institute of Earth Sciences<http://www.earthice.hi.is/page/ies_Eyjafjallajokull_eruption>, Icelandic Met Office<http://en.vedur.is/>, Iceland Review<http://icelandreview.com/>
Eyjafjallajökull Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=1702-02=> from the Global Volcanism Program
GAUA Banks Islands (SW Pacific) 14.27°S, 167.50°E; summit elev. 797 m
Based on analysis of MODIS<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> satellite imagery and information from the Vanuatu Geohazards Observatory, the Wellington VAAC<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> reported ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> plumes from Gaua during 13-16 and 19-21 April. The plumes regularly rose to altitudes of 3 km (10,000 ft) a.s.l.<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> The advisories on 14-15 April noted that the plumes were mostly steam. A spokesman for the Vanuatu Disaster Management Office described the activity as "huge, dark plumes" in an AAP news report.
Geologic Summary. The roughly 20-km-diameter Gaua Island, also known as Santa Maria, consists of a basaltic-to-andesitic stratovolcano<http://volcanoes.usgs.gov/images/pglossary/stratovolcano.php> with an 6 x 9 km wide summit caldera. Small parasitic vents near the caldera<http://volcanoes.usgs.gov/images/pglossary/caldera.php> rim fed Pleistocene<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> flows that reached the coast on several sides of the island; several littoral cones were formed where these lava flows reached the sea. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> eruptions. Construction of the historically active cone of Mount Garat (Gharat) and other small cinder cones in the SW part of the caldera has left a crescent-shaped caldera lake. The symmetrical, flat-topped Mount Garat cone is topped by three pit craters. The onset of eruptive activity from a vent<http://volcanoes.usgs.gov/images/pglossary/vent.php> high on the SE flank of Mount Garat in 1962 ended a long period of dormancy.
Sources: Vanuatu Geohazards Observatory<http://www.geohazards.gov.vu/>, Wellington Volcanic Ash Advisory Center (VAAC)<http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html>, Sydney Morning Herald/Australian Associated Press<http://news.smh.com.au/breaking-news-world/vanuatu-volcano-may-force-evacuations-20100420-sr10.html>
Gaua Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=0507-02=> from the Global Volcanism Program
Ongoing Activity
BEZYMIANNY Central Kamchatka (Russia) 55.978°N, 160.587°E; summit elev. 2882 m
KVERT<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> reported that during clear weather at Bezymianny during 8-13 April moderate fumarolic<http://volcanoes.usgs.gov/images/pglossary/fumarole.php> activity was observed and satellite data showed a weak thermal anomaly over the lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> dome. The Aviation Color Code<http://volcano.wr.usgs.gov/activity/alertsystem/index.php> level remained at Yellow.
Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. That eruption, similar to the 1980 event at Mount St. Helens, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome<http://volcanoes.usgs.gov/images/pglossary/LavaDome.php> growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)<http://www.kscnet.ru/ivs/kvert/index_eng.php>
Bezymianny Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-25=> from the Global Volcanism Program
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> reported that seismic activity from Karymsky was above background on 11 and 13-15 April. Satellite imagery revealed a thermal anomaly from the volcano during 11-12 April. The Aviation Color Code<http://volcano.wr.usgs.gov/activity/alertsystem/index.php> level remained at Orange.
Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano<http://volcanoes.usgs.gov/images/pglossary/stratovolcano.php> constructed within a 5-km-wide caldera<http://volcanoes.usgs.gov/images/pglossary/caldera.php> that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> flows less than 200 years old. Historical eruptions have been Vulcanian<http://volcanoes.usgs.gov/images/pglossary/vulcanian.php> or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)<http://www.kscnet.ru/ivs/kvert/index_eng.php>
Karymsky Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-13=> from the Global Volcanism Program
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 14-20 April activity reported by HVO<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> at Kilauea was continuing at the summit and the east rift<http://volcanoes.usgs.gov/images/pglossary/RiftZone.php> zone. At the summit, episodic rising and falling of the lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> column continued at the deep pit inset within the floor of Halema`uma`u crater. Cycles occurred every 10-20 minutes until becoming more sporadic the evening of 14 April. On 15-16 April there were only 1-2 cycles/day. Activity increased again on the 17th, with cycles every 10-30 minutes. Glow from the vent<http://volcanoes.usgs.gov/images/pglossary/vent.php> was visible when the rising and falling cycles were frequent. On most mornings the plume of gas and ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> from the summit vent drifted SW, depositing small amounts of tephra<http://volcanoes.usgs.gov/images/pglossary/tephra.php> near the vent. Sulfur dioxide emission rates measured at the summit on 12, 14, 15, and 19 April were in the 600-790 tonnes/day range.
At the east rift<http://volcanoes.usgs.gov/images/pglossary/RiftZone.php> zone, lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> flowed through tubes to supply surface flows that advanced down the Pulama pali towards the coastal plain; on 16 April those flows were within 300 m of the coastal plain. Sulfur dioxide emission rates from the summit and east rift zone<http://volcanoes.usgs.gov/images/pglossary/RiftZone.php> vents remained elevated. Geologists in the field on 17 April reported that the flow front had reached the E margin of the older Thanksgiving Eve Breakout (TEB) flow field on the coastal plain. On 19 April the flow front headed SE along the east margin of the TEB flow field, just W of the end of the Kalapana access road, and was 380 m NW of the viewing area.
Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera<http://volcanoes.usgs.gov/images/pglossary/caldera.php> or along one of the lengthy E and SW rift<http://volcanoes.usgs.gov/images/pglossary/RiftZone.php> zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone<http://volcanoes.usgs.gov/images/pglossary/RiftZone.php> that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)<http://hvo.wr.usgs.gov/>
Kilauea Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01-> from the Global Volcanism Program
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> reported that during 9-15 April seismic activity from Kliuchevskoi was above background levels. Strombolian<http://volcanoes.usgs.gov/images/pglossary/strombolian.php> activity periodically ejected material 200 m above the crater and lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> continued to flow down the flanks. Satellite imagery revealed a large daily thermal anomaly from the volcano, and gas-and-steam plumes that drifted about 85 km NE on 9 April. The Aviation Color Code<http://volcano.wr.usgs.gov/activity/alertsystem/index.php> level remained at Orange.
Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic<http://volcanoes.usgs.gov/images/pglossary/basalt.php> stratovolcano<http://volcanoes.usgs.gov/images/pglossary/stratovolcano.php> has produced frequent moderate-volume explosive and effusive<http://volcanoes.usgs.gov/images/pglossary/effusive.php> eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 700-m-wide summit crater has been frequently modified by historical<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included major explosive and effusive events from flank craters.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)<http://www.kscnet.ru/ivs/kvert/index_eng.php>
Kliuchevskoi Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-26=> from the Global Volcanism Program
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> reported that during 9-15 April seismic activity from Shiveluch was above background levels. Seismic data suggested that ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> plumes rose to about 7.5 km (24,600 ft) a.s.l.<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> on 8 April and up to 5.6 km (18,400 ft) a.s.l. the other days of the week. Ash plumes from hot avalanches were seen rising to an altitude of 3.7 km (12,100 ft) a.s.l. during 9-13 April. Satellite imagery revealed a large daily thermal anomaly from the lava dome<http://volcanoes.usgs.gov/images/pglossary/LavaDome.php> and a gas-and-steam plume that drifted about 75 km E on 13 April. The Aviation Color Code<http://volcano.wr.usgs.gov/activity/alertsystem/index.php> level remained at Orange.
Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome<http://volcanoes.usgs.gov/images/pglossary/LavaDome.php> complex was constructed during the Holocene<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> within a large breached caldera<http://volcanoes.usgs.gov/images/pglossary/caldera.php> formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic<http://volcanoes.usgs.gov/images/pglossary/andesite.php> volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome<http://volcanoes.usgs.gov/images/pglossary/LavaDome.php> that began growing in 1980. The largest historical<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> eruptions from Shiveluch occurred in 1854 and 1964.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)<http://www.kscnet.ru/ivs/kvert/index_eng.php>
Shiveluch Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-27=> from the Global Volcanism Program
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO<http://www.volcano.si.edu/reports/usgs/index.cfm?content=acronyms> reported that during 9-16 April activity at Soufrière Hills remained low. Several rockfalls occurred on the W side of the lava dome<http://volcanoes.usgs.gov/images/pglossary/LavaDome.php> on 15 April, and a small pyroclastic flow<http://volcanoes.usgs.gov/images/pglossary/PyroFlow.php> occurred on the Gages fan on 16 April; both were probably caused by heavy rainfall. The rain also generated lahars (mudflows) on several flanks. On the afternoon of 13 April large lahars occurred in the Belham valley, creating two large fans at the coast. Many of the lahars were hot with abundant associated steam and geysering.
Geologic Summary. The complex dominantly andesitic<http://volcanoes.usgs.gov/images/pglossary/andesite.php> Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes<http://volcanoes.usgs.gov/images/pglossary/LavaDome.php> emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava<http://volcanoes.usgs.gov/images/pglossary/lava.php> dome, no historical<http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html> eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash<http://volcanoes.usgs.gov/images/pglossary/ash.php> eruptions beginning in that year were later accompanied by lava-dome<http://volcanoes.usgs.gov/images/pglossary/LavaDome.php> growth and pyroclastic flows<http://volcanoes.usgs.gov/images/pglossary/PyroFlow.php> that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.
Source: Montserrat Volcano Observatory (MVO)<http://www.mvo.ms/>
Soufrière Hills Information<http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05=> from the Global Volcanism Program
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---------- Forwarded message ----------
From: "Venzke, Ed" <VENZKEE@xxxxxx>
To: Volcano_Listserv <volcano@xxxxxxx>
Date: Thu, 22 Apr 2010 13:23:16 -0400
Subject: SI/USGS Weekly Volcanic Activity Report, 14-20 April 2010
SI/USGS Weekly Volcanic Activity Report
14-20 April 2010
Sally Kuhn Sennert - Weekly Report Editor
New Activity/Unrest: | Barren Island, Andaman Is | Eyjafjallajökull, Southern Iceland | Gaua, Banks Islands (SW Pacific)
Ongoing Activity: | Bezymianny, Central Kamchatka (Russia) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat
The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.
New Activity/Unrest
BARREN ISLAND Andaman Is 12.278°N, 93.858°E; summit elev. 354 m
Based on analysis of satellite imagery, the Darwin VAAC reported that a plume from Barren Island rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifting 55 km N on 19 April. However, ash could not be identified from the satellite data.
Geologic Summary. Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit of volcano that rises from a depth of about 2,250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with walls 250-350 m high. The caldera, which is open to the sea on the W, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic-flow and -surge deposits. The morphology of a fresh pyroclastic cone that was constructed in the center of the caldera has varied during the course of historical eruptions. Lava flows fill much of the caldera floor and have reached the sea along the western coast during historical eruptions.
Map
Source: Volcanic Ash Advisory Centre (VAAC)
Barren Island Information from the Global Volcanism Program
EYJAFJALLAJOKULL Southern Iceland 63.63°N, 19.62°W; summit elev. 1666 m
The Institute of Earth Sciences at the Nordic Volcanological Center (NVC) reported that a new set of craters opened in the early morning of 14 April under the ice-covered central summit caldera of Eyjafjallajökull. This eruptive phase was preceded by a swarm of earthquakes and the onset of tremor. Aerial observations revealed a series of vents along a 2-km-long N-S fissure, with meltwater flowing down both the N and S slopes of the volcano. An ash plume rose to more than 8 km altitude, and was deflected to the E by winds. Jokulhlaups (floods of meltwater) reached the lowlands around the volcano with peak flow around noon, damaging roads, infrastructure, and farmlands. There were no fatalities due to previous evacuations. Tephra-fall was reported in SE Iceland. A second jokulhlaup/lahar traveled down the Markarfljot valley that evening.
On 15 April the eruption plume reached mainland Europe, causing the closure of large areas of airspace. Activity continued during 16 April at a similar level as the previous day, with ash generation and pulses of meltwater causing jokulhlaup/lahars in the evening. The next day there was some variability in seismic tremor and tephra generation, but overall the activity remained stable. A pulsating eruptive column reached above 8 km altitude, and lightning was frequently seen within the plume.
Over the first 72 hours of explosive activity, scientists estimated that the eruption had produced 140 million cubic meters of tephra. An update from NVC on 21 April noted that activity had declined in the previous few days by an order of magnitude, though phreatomagmatic explosions were still occurring, sending plumes about 3 km high. Lava spattering was seen at the craters, and meltwater flows were minor. Seismicity was not decreasing at that time, and samples collected on 19 April were of the same intermediate composition (58% SiO2) as early in the explosive phase, but with more fluorine.
The ash cloud resulted in the cancellation of tens of thousands of daily flights, both into and out of major European cities, after 15 April. Although on 19 April the plume was only rising 1 km above the summit, it was ascending to altitudes of 5-7 km (15-20,000 ft) as it drifted to the S. Beginning on 20 April, after a decrease in activity and a significant dissipation of the plume, many previously closed areas were at least partially opened for limited service.
Geologic Summary. Eyjafjallajökull (also known as Eyjafjöll) is located west of Katla volcano. Eyjafjallajökull consists of an E-W-trending, elongated ice-covered basaltic-andesite stratovolcano with a 2.5-km-wide summit caldera. Fissure-fed lava flows occur on both the eastern and western flanks of the volcano, but are more prominent on the western side. Although the 1666-m-high volcano has erupted during historical time, it has been less active than other volcanoes of Iceland's eastern volcanic zone, and relatively few Holocene lava flows are known. An intrusion beneath the south flank from July-December 1999 was accompanied by increased seismic activity and was constrained by tilt measurements, GPS-geodesy and InSAR. The last historical eruption of Eyjafjallajökull prior to an eruption in 2010 produced intermediate-to-silicic tephra from the central caldera during December 1821 to January 1823.
Map
Sources: Institute of Earth Sciences, Icelandic Met Office, Iceland Review
Eyjafjallajökull Information from the Global Volcanism Program
GAUA Banks Islands (SW Pacific) 14.27°S, 167.50°E; summit elev. 797 m
Based on analysis of MODIS satellite imagery and information from the Vanuatu Geohazards Observatory, the Wellington VAAC reported ash plumes from Gaua during 13-16 and 19-21 April. The plumes regularly rose to altitudes of 3 km (10,000 ft) a.s.l. The advisories on 14-15 April noted that the plumes were mostly steam. A spokesman for the Vanuatu Disaster Management Office described the activity as "huge, dark plumes" in an AAP news report.
Geologic Summary. The roughly 20-km-diameter Gaua Island, also known as Santa Maria, consists of a basaltic-to-andesitic stratovolcano with an 6 x 9 km wide summit caldera. Small parasitic vents near the caldera rim fed Pleistocene lava flows that reached the coast on several sides of the island; several littoral cones were formed where these lava flows reached the sea. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash eruptions. Construction of the historically active cone of Mount Garat (Gharat) and other small cinder cones in the SW part of the caldera has left a crescent-shaped caldera lake. The symmetrical, flat-topped Mount Garat cone is topped by three pit craters. The onset of eruptive activity from a vent high on the SE flank of Mount Garat in 1962 ended a long period of dormancy.
Map
Sources: Vanuatu Geohazards Observatory, Wellington Volcanic Ash Advisory Center (VAAC), Sydney Morning Herald/Australian Associated Press
Gaua Information from the Global Volcanism Program
Ongoing Activity
BEZYMIANNY Central Kamchatka (Russia) 55.978°N, 160.587°E; summit elev. 2882 m
KVERT reported that during clear weather at Bezymianny during 8-13 April moderate fumarolic activity was observed and satellite data showed a weak thermal anomaly over the lava dome. The Aviation Color Code level remained at Yellow.
Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. That eruption, similar to the 1980 event at Mount St. Helens, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.
Map
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Bezymianny Information from the Global Volcanism Program
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that seismic activity from Karymsky was above background on 11 and 13-15 April. Satellite imagery revealed a thermal anomaly from the volcano during 11-12 April. The Aviation Color Code level remained at Orange.
Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996.
Map
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Karymsky Information from the Global Volcanism Program
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 14-20 April activity reported by HVO at Kilauea was continuing at the summit and the east rift zone. At the summit, episodic rising and falling of the lava column continued at the deep pit inset within the floor of Halema`uma`u crater. Cycles occurred every 10-20 minutes until becoming more sporadic the evening of 14 April. On 15-16 April there were only 1-2 cycles/day. Activity increased again on the 17th, with cycles every 10-30 minutes. Glow from the vent was visible when the rising and falling cycles were frequent. On most mornings the plume of gas and ash from the summit vent drifted SW, depositing small amounts of tephra near the vent. Sulfur dioxide emission rates measured at the summit on 12, 14, 15, and 19 April were in the 600-790 tonnes/day range.
At the east rift zone, lava flowed through tubes to supply surface flows that advanced down the Pulama pali towards the coastal plain; on 16 April those flows were within 300 m of the coastal plain. Sulfur dioxide emission rates from the summit and east rift zone vents remained elevated. Geologists in the field on 17 April reported that the flow front had reached the E margin of the older Thanksgiving Eve Breakout (TEB) flow field on the coastal plain. On 19 April the flow front headed SE along the east margin of the TEB flow field, just W of the end of the Kalapana access road, and was 380 m NW of the viewing area.
Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Map
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Kilauea Information from the Global Volcanism Program
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 9-15 April seismic activity from Kliuchevskoi was above background levels. Strombolian activity periodically ejected material 200 m above the crater and lava continued to flow down the flanks. Satellite imagery revealed a large daily thermal anomaly from the volcano, and gas-and-steam plumes that drifted about 85 km NE on 9 April. The Aviation Color Code level remained at Orange.
Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included major explosive and effusive events from flank craters.
Map
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Kliuchevskoi Information from the Global Volcanism Program
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 9-15 April seismic activity from Shiveluch was above background levels. Seismic data suggested that ash plumes rose to about 7.5 km (24,600 ft) a.s.l. on 8 April and up to 5.6 km (18,400 ft) a.s.l. the other days of the week. Ash plumes from hot avalanches were seen rising to an altitude of 3.7 km (12,100 ft) a.s.l. during 9-13 April. Satellite imagery revealed a large daily thermal anomaly from the lava dome and a gas-and-steam plume that drifted about 75 km E on 13 April. The Aviation Color Code level remained at Orange.
Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
Map
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Shiveluch Information from the Global Volcanism Program
SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 9-16 April activity at Soufrière Hills remained low. Several rockfalls occurred on the W side of the lava dome on 15 April, and a small pyroclastic flow occurred on the Gages fan on 16 April; both were probably caused by heavy rainfall. The rain also generated lahars (mudflows) on several flanks. On the afternoon of 13 April large lahars occurred in the Belham valley, creating two large fans at the coast. Many of the lahars were hot with abundant associated steam and geysering.
Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.
Map
Source: Montserrat Volcano Observatory (MVO)
Soufrière Hills Information from the Global Volcanism Program
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