Volcano Update from Archive



AVO/USGS Volcanic Activity Notice

Volcano: Iliamna (CAVW #1103-02-)

Current Volcano Alert Level: ADVISORY
Previous Volcano Alert Level: NORMAL

Current Aviation Color Code: YELLOW
Previous Aviation Color Code: GREEN

Issued: Friday, March 9, 2012, 1:02 PM AKST (20120309/2202Z)
Source: Alaska Volcano Observatory
Notice Number: 2012/A5
Location: N 60 deg 1 min W 153 deg 5 min
Elevation: 10016 ft (3053 m)
Area: Cook Inlet-South Central Alaska

Volcanic Activity Summary: Over the past three months the earthquake rate at Iliamna Volcano has steadily increased and now exceeds normal background levels. Although it is not certain that this sustained increase in earthquake activity represents the movement of magma at depth, it is a significant change and AVO has increased the Alert Level to Advisory and the Aviation Color Code to Yellow. The current activity does not mean an eruption is imminent or certain. A similarly energetic episode of seismic unrest from September 1996 to February 1997 was likely related to the intrusion of new magma at depth, but an eruption did not occur.

AVO will continue to observe Iliamna closely, will conduct additional investigations and report on them as warranted.

Recent Observations:
[Volcanic cloud height] None

Hazard Analysis:
[General hazards] The increased level of seismic activity could invigorate the hydrothermal system and result in increases in volcanic gas and vapor output similar to the 1996 episode. It is also possible that increased volcanic gas emissions will provide more heat to the upper part of the volcano and along with increased seismic activity may initiate avalanches of rock and ice off the steep faces of the summit.

Remarks: Iliamna Volcano is located on the western side of lower Cook Inlet in Lake Clark National Park and Preserve. The volcano has a summit altitude of 3053 m (10,016 feet) above sea level and the volcanic edifice supports an extensive cover of snow and glacier ice. An active fumarole field is present on the upper eastern face of the volcano and on calm days, vapor emissions are often visible. There have been no known historical eruptions of Iliamna Volcano, but volcanic deposits preserved on the flanks of the volcano indicate that there have been multiple episodes of explosive eruptive activity in the past 2500 years and the most recent explosive event occurred about 300 years ago. Occasional large ice and rock avalanches, and changes in glacial ice have been observed in the past at Iliamna, but are not directly related to volcanic activity. The volcano is located 210 km (130 miles) southwest of Anchorage and 100 km (60 miles) northwest of Homer.

Contacts:
David Schneider, Acting Scientist-in-Charge, USGS
djschneider@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF
steve@giseis.alaska.edu (907) 474-7131

Next Notice: A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at
http://www.avo.alaska.edu

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.
(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:(20120309/2202Z)
(3) Volcano:Iliamna (CAVW# 1103-02-)
(4) Current Color Code:YELLOW
(5) Previous Color Code:green
(6) Source:Alaska Volcano Observatory
(7) Notice Number:2012/A5
(8) Volcano Location:N 60 deg 1 min W 153 deg 5 min
(9) Area:Cook Inlet-South Central Alaska
(10) Summit Elevation:10016 ft (3053 m)
(11) Volcanic Activity Summary:Over the past three months the earthquake rate at Iliamna Volcano has steadily increased and now exceeds normal background levels. Although it is not certain that this sustained increase in earthquake activity represents the movement of magma at depth, it is a significant change and AVO has increased the Alert Level to Advisory and the Aviation Color Code to Yellow. The current activity does not mean an eruption is imminent or certain. A similarly energetic episode of seismic unrest from September 1996 to February 1997 was likely related to the intrusion of new magma at depth, but an eruption did not occur.

AVO will continue to observe Iliamna closely, will conduct additional investigations and report on them as warranted.
(12) Volcanic cloud height:None
(13) Other volcanic cloud information:Unknown
(14) Remarks:Iliamna Volcano is located on the western side of lower Cook Inlet in Lake Clark National Park and Preserve. The volcano has a summit altitude of 3053 m (10,016 feet) above sea level and the volcanic edifice supports an extensive cover of snow and glacier ice. An active fumarole field is present on the upper eastern face of the volcano and on calm days, vapor emissions are often visible. There have been no known historical eruptions of Iliamna Volcano, but volcanic deposits preserved on the flanks of the volcano indicate that there have been multiple episodes of explosive eruptive activity in the past 2500 years and the most recent explosive event occurred about 300 years ago. Occasional large ice and rock avalanches, and changes in glacial ice have been observed in the past at Iliamna, but are not directly related to volcanic activity. The volcano is located 210 km (130 miles) southwest of Anchorage and 100 km (60 miles) northwest of Homer.
(15) Contacts:
David Schneider, Acting Scientist-in-Charge, USGS
djschneider@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF
steve@giseis.alaska.edu (907) 474-7131

(16) Next Notice:A new VONA will be issued if conditions change significantly or alert levels are modified. While a VONA is in effect, regularly scheduled updates are posted at
http://www.avo.alaska.edu