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Iliamna reported activity





Start:December 22, 2011 Observed

Steam: BibCard
Eruption Type:Not an eruption.

Description: **As of this writing (March 19, 2012), Iliamna is exhibiting unrest, and has not erupted.

On March 9, 2012, citing an increase in earthquakes at Iliamna over the past three months, AVO raised the alert level at Iliamna to ADVISORY and the aviation color code to YELLOW. Text from the March 9 VAN/VONA reads in part: "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 similarily 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's weekly update on March 16, 2012, further reported: "Seismic activity at Iliamna Volcano remains above background. During the past week, small earthquakes continued to occur below the general vicinity of the volcano at depths mostly less than 4 km (2.5 miles) below sea level. Additional small and shallow earthquakes that may reflect movement of ice and other surface processes are also being recorded. On several satellite images this week, a plume extended up to 35 miles downwind from the summit area of the volcano; the composition of this plume is uncertain by likely dominated by water vapor. Long-lived fumaroles at the summit of Iliamna frequently produce visible plumes; this week's plumes appear to be more robust than normal."

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Page modified: June 11, 2014 13:55
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