Tuesday, March 02, 2010

Further information on the Chile quake

Including why the tsunami turned out to be not nearly as bad as feared.
Tim Henstock of the National Oceanography Centre at the University of Southampton, UK, speculates that the reason might be that Saturday's earthquake ruptured a relatively small segment of fault – around 350 kilometres. The length of fault rupture determines the distance at which a tsunami begins to lose energy. By comparison, the magnitude-9.1 earthquake that generated the 2004 Indian ocean tsunami ruptured around 1600 kilometres of fault.
I'd wondered about that; I remembered the 2004 quake had shifted a huge length of fault, and wondered if this one might have been a shorter distance, or possibly more a lateral shift than vertical. Looks like it was a much shorter distance.

I'll note, somebody mentioned that Chile has pretty good building standards due to the quake threat; that there's only about 700 confirmed dead at this point would indicate their standards work pretty well.

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