Saturday, May 31, 2008

West coast 'locked fault' may be unzipping

Scientists have placed a series of earthquakes in Oregon directly on the west coast 'big fault'. This type of fault is unusual in that it appears to never produce little earthquakes, only big ones. At first, it seems this would violate the standard law of self-similarity, but these big 'smooth' faults have a different fractal dimension than, maybe, an interior fault.

That means there are still little earthquakes setting up for the big one, but the slope is much steeper, which means fewer little earthquakes before KABLAM! The big question about these 'Niners', is whether they need a bunch of eights along the fault first. Most likely not. If the critical displacement is tiny (because the fault is smooth), then M6's could set everything up, and when it comes to the first M7 (minimum magnitude to rupture the whole crust), everything just falls like dominoes.

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