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ARCHIVED REPORT
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ALASKA VOLCANO OBSERVATORY

INFORMATION RELEASE

Tuesday, November 29, 2005 12:15 PM AKST (2115 UTC)




AUGUSTINE VOLCANO (CAVW#1103-01-)

59.3633°N 153.4333°W, Summit Elevation 4134 ft (1260 m)

Current Level of Concern Color Code: YELLOW

Previous Level of Concern Color Code: GREEN



AVO has detected important changes in earthquake activity and ground deformation at Augustine Volcano in southern Cook Inlet. These data are consistent with renewed volcanic unrest. AVO is therefore raising the level-of-concern color code from green to YELLOW and will continue to monitor activity closely. There is no indication that an eruption is imminent or certain.



Beginning in May 2005, there has been a slow increase in the number of earthquakes located under Augustine Volcano. The earthquakes are generally small (less than magnitude 1.0) and concentrate roughly 1 km below the volcano's summit. These earthquakes have slowly increased from 4-8 earthquakes/day to 20-35 earthquakes/day. Additionally, data from a 6-station Global Positioning System (GPS) network on Augustine Volcano indicate that a slow, steady inflation of the volcano started in mid-summer 2005 and continues at present. The GPS benchmark located nearest the summit has moved a total of 2.5 cm (1 inch). This motion is consistent with a source of inflation or pressure change centered under the volcano. This is the first such deformation detected at Augustine Volcano since measurements began just prior to the 1986 eruption.



No reports of increased steaming have been received by AVO, nor have satellite data shown increased thermal activity.



Historic eruptions of Augustine typically begin with explosive bursts that may send plumes of ash to 30,000-40,000 feet above sea level. The primary hazards to communities, aviation, and mariners in Cook Inlet and parts of south-central Alaska from an Augustine eruption are ash fall and drifting ash clouds. In 1986, 6 mm (0.25 inch) of ash fell in Homer, 120 km (75 mi) east of Augustine and light ashfall was recorded in Anchorage, 290 km (180 mi) away. Hot, ground-hugging flows of volcanic rock debris called pyroclastic flows may form during an eruption and could be hazardous to people, aircraft, or boats on or in the immediate vicinity of the island.



Island volcanoes can generate tsunamis by collapse into the sea. There is no evidence that conditions are developing that would lead to a major volcanic landslide or similar event at Augustine that, upon entering Cook Inlet, could generate a tsunami. No tsunami waves were generated during any of the last five eruptions of Augustine Volcano.



The full hazard assessment for Augustine Volcano can be obtained at http://www.avo.alaska.edu/pdfs/augustine_ofr.pdf



Augustine Volcano is a 1260 m high (4134 ft) conical-shaped stratovolcano located on Augustine Island in southern Cook Inlet, about 290 km (180 mi) southwest of Anchorage, Alaska. Augustine is the most historically active volcano in the Cook Inlet region. Historical eruptions occurred in 1812, 1883, 1908, 1935, 1963-64, 1976, and 1986. These eruptions were primarily explosive events that produced volcanic ash clouds and pyroclasic flows. During the 1883 eruption, a volcanic rock avalanche occurred on the north flank of the volcano; it flowed into Cook Inlet and initiated a tsunami observed at Nanwalek, about 90 km to the east.





ABBREVIATED COLOR CODE KEY (contact AVO for complete description):

GREEN volcano is dormant; normal seismicity and fumarolic activity occurring

YELLOW volcano is restless; eruption may occur

ORANGE volcano is in eruption or eruption may occur at any time

RED significant eruption is occurring or explosive eruption expected at any time



VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu

RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478



CONTACT INFORMATION:

Tom Murray, Scientist-in-Charge, USGS

tlmurray@usgs.gov (907) 786-7497



John Eichelberger, Coordinating Scientist, UAF-GI

eich@gi.alaska.edu (907) 474-5530



The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.
VOLCANO ALERT LEVELS
NORMAL
Volcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.
ADVISORY
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
WATCH
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway but poses limited hazards.
WARNING
Hazardous eruption is imminent, underway, or suspected.

AVIATION COLOR CODES
GREEN
Volcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.
YELLOW
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
ORANGE
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway with no or minor volcanic-ash emissions [ash-plume height specified, if possible].
RED
Eruption is imminent with significant emission of volcanic ash into the atmosphere likely OR eruption is underway or suspected with significant emission of volcanic ash into the atmosphere [ash-plume height specified, if possible].

PDF version of these definitions
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Page modified: May 27, 2014 10:23
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