Cleveland, Alaska: another small explosion 15 March 2012

Cleveland volcano in the Aleutians had another small eruption on the afternoon of 13 March, reports the Alaska Volcano Observatory, the third such event in a week (the previous eruptions were on 7 March and 10 March). The AVO status report, issued on 14 March at 1134 local time (1934Z) describes what happened:

Yesterday afternoon at approximately 2:55 pm AKDT (22:55 UTC), AVO infrasound and seismic networks detected a small explosion at Cleveland. Clouds prevented a clear view of the volcano at the time of the explosion, however, ash was not observed rising through the cloud deck suggesting relatively minor ash emission.

The Volcano Alert Level for Cleveland remains at Watch, the Aviation Colour Code at Orange. The same report notes that seismicity remains elevated at Iliamna volcano (which remains at Yellow/Advisory).

News
Cleveland volcano explodes for the third time – alaskapublic.org, 14 March 2012

Information
Global Volcanism Program: Cleveland – summary information for Cleveland (1101-24-)
Global Volcanism Program: Iliamna – summary information for Iliamna (1103-02-)
AVO Cleveland Activity Page – information on current activity at Cleveland
AVO Iliamna Activity Page – information on current activity at Iliamna
Alaska Volcano Observatory – AVO main page

Alaska: another small explosion at Cleveland 11 March 2012

The Alaska Volcano Observatory reports another small explosive event at Cleveland volcano, following the small explosion detected on 7 March. This one happened in the afternoon (local time) of 9 March, as the AVO Volcanic Activity Notification reports:

Another small, short duration explosion from Cleveland Volcano was detected on distant seismic stations and infrasound arrays on about 1:55 March 10, UTC (4:05 PM March 9, AKST.) No ash cloud from this event was detected in satellite imagery probably due to cloudy weather conditions. This explosion was similar to recent small events that occurred on March 7 and in December 2011. These events produced small ash clouds that dissipated quickly and did not affect air traffic.

The Volcano Alert Level for Cleveland remains at Watch, the Aviation Colour Code at Orange. The same report gives an update on Iliamna, where seismic activity remains above background. Iliamna’s alert status is currently one notch below Cleveland’s, at Volcano Alert Level Advisory, Aviation Colour Code Yellow.

News
Cleveland volcano rocked by explosion – Anchorage Daily News, 10 March 2012.

Information
Global Volcanism Program: Cleveland – summary information for Cleveland (1101-24-)
Global Volcanism Program: Iliamna – summary information for Iliamna (1103-02-)
AVO Cleveland Activity Page – information on current activity at Cleveland
AVO Iliamna Activity Page – information on current activity at Iliamna
Alaska Volcano Observatory – AVO main page

Alaskan activity update: Cleveland and Iliamna (updated) 9 March 2012

Beautiful, symmetrical Cleveland volcano in the Aleutians, which has been rumbling on and off over the last few months as its lava dome has grown, produced a small eruption last night, reports the Alaska Volcano Observatory:

A small, short duration explosion was detected from Cleveland Volcano on distant seismic stations and infrasound arrays. The time of the explosion was approximately 4:05 UTC March 8 (7:05 PM March 7, AKST.) Weather cloud conditions prevented the detection of an eruption cloud in satellite images or visual observation of the summit. This explosion was similar to recent small events that occurred in December 2011 and produced small ash clouds that dissipated quickly and did not affect air traffic. At this time, no further activity has been detected.

Alaska Public Radio gets a bit over-excited, reporting that ‘Cleveland Volcano has blown its top again’. Talking of Cleveland blowing its top is putting it a little strongly. This latest eruption, as AVO says, was a small event. There may well be more of this kind of small-scale explosion, often caused by localized rock fracturing and movement, as the lava dome continues to grow. Cleveland does not have a real-time seismic monitoring network, but AVO will continue to monitor Cleveland closely. Cleveland is currently at Orange/Watch.

UPDATE. An article in the Anchorage Daily News quotes Steve McNutt of the Alaska Volcano Observatory airing the possibility that the explosion last night may have ‘blasted away a lava dome building inside the volcano’s summit crater’. AVO volcanologists are hoping that satellite images will shortly show what exactly happened during this eruption. It will be interesting to see if all or part of the lava dome has indeed gone missing.

Another Alaskan volcano, Iliamna, which does have real-time seismic monitoring, has been experiencing episodes of increased earthquake activity and is being carefully watched by AVO. So far the alert status for Iliamna has not been raised and remains at Green/Normal.

News
4.1 earthquake comes as scientists watch Alaska’s Iliamna volcano – Alaska Dispatch, 8 March 2012
Explosion detected at Alaska’s Cleveland volcano – Alaska Dispatch, 8 March 2012
Two Alaska volcanoes show signs of activity – Chicago Tribune, 8 March 2012
Seismic stations pick up Cleveland blast – alaskapublic.org, 8 March 2012
Blast shakes restless volcano in remote Aleutian Islands – Anchorage Daily News, 8 March 2012

Information
Global Volcanism Program: Cleveland – summary information for Cleveland (1101-24-)
Global Volcanism Program: Iliamna – summary information for Iliamna (1103-02-)
AVO Cleveland Eruption Page – information on current activity at Cleveland
Alaska Volcano Observatory – AVO main page