Thursday, July 21, 2005

Another day, another tremor, another good show on Mount St Helens

Early this morning (03:00) there was another magnitude 3.1 earthquake and associated bright outburst from the lavadome on Mount St Helens. This is almost getting to be a regular occurance!

3 Comments:

Anonymous Cathy said...

Have any of the scientists commented on the significance of these stronger quakes? I haven't seen anything anywhere that calls them harmonic, but the increased activity gives me the willies!

2005-07-23, 1:32 PM  
Blogger Daz said...

There have been a few stories in the press about the increased activity, for example this AP story in the Olympian (http://159.54.227.3/apps/pbcs.dll/article?AID=/20050722/NEWS06/507220339).

And if you look at the depth of all the recent quakes they are all quite shallow.


My guess is that we are seeing the effects of the crumbling lavadome, rather than a build up of pressure deeper in the mountain. But that's just my 2c worth...

2005-07-23, 1:45 PM  
Anonymous Kevin said...

Historically, earthquake events have been rather shallow at MSH. between 1-3 miles. even when this began in october. last week's 3+ events i think were either the new dome 'sticking', or some kind of new magma coming shallow. As rockfalls continue, their unique seismic signature can be seen ( a sort of diffuse, mag. 1-2 event that doesnt show up on distant seismometers) or, interestingly, no signal at all.
The 3.0+ events all caused rockfalls, and also coincided with the regular microquakes reappearing. It looks as if both have stopped this week.
So my guess is that those quakes were not the result of rockfalls. not harmonic tremor either. but maybe magma related.

2005-07-28, 8:27 AM  

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