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ARCHIVED REPORT
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ALASKA VOLCANO OBSERVATORY

INFORMATION RELEASE

Wednesday, October 5, 2005 2:15 PM AKDT (2215 UTC)




TANAGA VOLCANO (CAVW#1101-08-)

51.885°N 178.1458°W, Summit Elevation 5925 ft (1806 m)

Current Level of Concern Color Code: GREEN



The Alaska Volcano Observatory (AVO) has detected a small increase in earthquake activity beneath Tanaga Volcano. The increased earthquake activity began late on October 1 and continues. The number of located events has ranged from 68 to 15 each day. This is in contrast to the low rate of less than one earthquake per month recorded since the seismic network was installed in 2003. Swarms of earthquakes such as this are common at volcanoes such as Tanaga and the size and depth of these events do not suggest that eruptive activity is imminent. Satellite data show nothing unusual. The color code for Tanaga remains at Green.



The earthquakes are centered roughly two km northeast of the summit of Tanaga Volcano and range in depth between 10 and 20 km below sea level. The largest event had a magnitude of 1.7 and most range in magnitude between 0.5 and 1.5. AVO continues to monitor the volcano closely using seismic and satellite data.



Tanaga is a remote 1806 m high (5,925 ft) high stratovolcano located roughly 105 km (63 miles) west of Adak in the Andreanof Islands. The last known eruption of Tanaga occurred in 1914 and earlier eruptions were reported in 1763-1770, 1791, and 1829.





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



Steve McNutt, Acting Coordinating Scientist, UAF-GI

steve@giseis.alaska.edu (907) 474-7131



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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