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ARCHIVED REPORT
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ALASKA VOLCANO OBSERVATORY

WEEKLY UPDATE

Friday, April 29, 2005 15:35 PM AKDT (23:35 UTC)


MOUNT SPURR VOLCANO (CAVW#1103-04)

6118' N 15215' W, Summit Elevation 11,070 ft (3,374 m)

Current Level of Concern Color Code: YELLOW



Elevated levels of seismicity continue to be recorded at Mount Spurr. A thermal imaging over flight of the summit melt pit region was conducted on Monday, April 25, and recorded temperatures as hot as 40 degrees Celsius in scattered patches of exposed rock. These values are similar to those recorded in September 2004 during the last such mission. Discoloration of the lake contained in the summit crater was observed and a strong smell of sulfur gases was detected, indicating continued gas emissions. The size of the summit melt pit was estimated to be approximately 250 m (820 ft) in diameter, and continues to grow as the summit snow pack collapses into the lake. No unusual activity was observed in satellite and web camera images this week. Conditions at Crater Peak and Mount Spurr do not indicate that an eruption is imminent.



Both Spurr and Crater Peak are emitting volcanic gases, including carbon dioxide (CO2), sulfur dioxide (SO2), and hydrogen sulfide (H2S) which may be hazardous to recreational visitors. Skiers, snowboarders, mountaineers, and pilots (especially those landing near the summit area) will find information regarding proximal hazards online at: http://www.avo.alaska.edu/activity/Spurr.php



Mount Spurr volcano is an ice- and snow-covered stratovolcano located on the west side of Cook Inlet. The only known historical eruptions occurred in 1953 and 1992 from the Crater Peak flank vent located 3.5 km (2 mi) south of the summit of Mount Spurr. These eruptions were brief, explosive, and produced columns of ash that rose up to 20 km (65,000 ft) above sea level and deposited several mm of ash in south-central Alaska, including approximately 6 mm of ash on Anchorage in 1953. The last known eruption from the summit of Mount Spurr was more than 5,000 years ago. Primary hazards during future eruptions include far-traveled ash clouds, ash fall, pyroclastic flows, and lahars or mudflows that could inundate drainages all sides of the volcano, but primarily on the south and east flanks.



MOUNT PEULIK VOLCANO (CAVW#1102-13A)

5745'N 15621'W, Summit Elevation 4,836 ft. (1,474 m)

Current Level of Concern Color Code: GREEN



AVO is today adding Mount Peulik volcano to the list of seismically monitored Alaskan volcanoes. A 7-station seismic network was installed at Mount Peulik volcano last summer and has operated successfully through the winter. The addition of Mount Peulik brings the total of seismically monitored volcanoes to 28.



In many lists of volcanoes, including that on the AVO web site, Peulik is listed under Ugashik-Peulik.



Mount Peulik, a small stratovolcano about 10 km (6.2 mi) in diameter at the base, is located just south of Becharof Lake on the Alaska Peninsula, approximately 540 km (325 mi) southwest of Anchorage and 115 km (70 mi) south of King Salmon. The volcano partially covers the northern margin of Ugashik caldera, an older circular structure about 5 km (3.1 mi) in diameter. Peulik's summit crater - about 1.5 km (1 mi) in diameter - is breached on the west side. A lava dome occupies the summit crater. This dome, and possibly earlier predecessors, was the source of a thick block-and-ash flow deposit that covers about 40 square km (15 sq. mi.) of the western flank of the volcano. Debris avalanche deposits representing a flank collapse cover an area of 75 square km (29 sq. mi.) northwest of the volcano. Old lava flows from flank eruptions of Peulik extend north from the volcano as far as Becharof Lake.



The only known historic eruption of Peulik occurred around 1814. A report of that eruption stated that Peulik's "summit collapsed with a rumble, covering the base with enormous boulders. For about a week after this event, vapor rose from almost the entire surface of the mountain." There was also a report of "smoke" coming from the crater in 1852.



OTHER ALASKA VOLCANOES

Seismic activity is monitored in real time at 28 volcanoes in Alaska. Satellite images of all Alaskan volcanoes are analyzed daily for evidence of ash plumes and elevated surface temperatures. Some volcanoes may currently display anomalous behavior but are not considered to be at a dangerous level of unrest. Wrangell, Redoubt, Iliamna, Augustine, Snowy, Griggs, Katmai, Novarupta, Trident, Mageik, Martin, Peulik, Aniakchak, Veniaminof, Pavlof, Dutton, Isanotski, Shishaldin, Fisher, Westdahl, Akutan, Makushin, Okmok, Great Sitkin, Kanaga, Tanaga, and Gareloi volcanoes are in color code GREEN. All are at or near normal levels of background seismicity. AVO did not detect ash plumes or significant elevated surface temperatures in the vicinity of any volcano.



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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URL: avo.alaska.edu/activity/avoreport_archives.php
Page modified: May 27, 2014 10:23
Contact Information: AVO Web Team

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