Shishaldin, Semisopochnoi Show Elevated Activity

Aug 11, 2014

Summit of Mt. Shishaldin
Credit photovolcanica.com

Flareups at Shishaldin and earthquakes at Semisopochnoi are among the latest occurrences at Alaska’s volcanoes.  KDLG’s Chase Cavanaugh has more.

In its latest update, the Alaska Volcano Observatory has noted increased activity among several major peaks.  First among them is Shishaldin, which is located at the eastern end of the Aleutian Island chain.  Sound waves were detected in Dillingham along with what Acting Scientist-in-Charge Michelle Coombs calls low-level eruptive activity.

“We see evidence for very low levels of ash emission as well as evidence that there may be lava up in the vent area of the volcano.”

She says this is a common occurrence at Shishaldin.

“It often has a steam plume, and small amounts of ash might come out in that plume.  It has a very deep crater at its summit, and sometimes when we get a good view down into that crater, we can see a little bit of lava down there or very very hot rock, indicating that magma is close to the surface.  This is all very low level activity and very common at Shishaldin.”

AVO raised the mountain’s color code to ORANGE as a result. 

Another source of volcanic activity is Semisopochnoi, which is located on the western end of the Aleutian Islands.  While there isn’t lava activity like Shishaldin, Coombs says AVO has detected earthquakes there since June.

“The network started detecting quite a number of small, what we call “volcano tectonic earthquakes.”  These are little earthquakes that are right under the volcano.  Over the summer, we’ve been recording up to dozens of these things a day, and we raised the color code at that volcano to yellow to indicate that we think that this earthquake activity might be indicative that magma is making its way up toward the surface.”

Despite these concerns, the tremors have recently tapered off.

“In the last few weeks, the number of earthquakes per day is down, so the activity seems to be tapering off, which also happens a lot.  You get these swarms of earthquakes and then they just go away again and no eruption every takes place.”

One final source of activity was Cleveland Volcano, one of the most active in the Aleutians.  While there was nothing severe, Coombs notes there is still activity.

“They’re noticing frequent rockfalls at Cleveland and just kind of degassing and steam plumes that they’re seeing pretty regularly when the weather allows.  That volcano too is at color code yellow and exhibiting low levels of unrest.”

No other volcanoes showed significant activity.  Additional information on these peaks, as well as others in the state, can be found at the website of the Alaska Volcano Observatory, accessible at avo.alaska.edu.