A closer look at the epicentral region, Chile quake

The figure below is another piece of the poster on the Chile quake available from the U.S. Geological Survey.

This figure includes quakes with magnitudes > 5.5, whereas the last figure only showed quakes with magnitudes > 7.

A couple of interesting patterns according to my eye:

1. Note that the epicenter of the main quake (yellow star) seems to fill a gap in the pattern of epicenter locations parallel to the Peru-Chile Trench, as if this part of the plate boundary was accumulating stress and needed some release. This, in fact, does happen (as I have previously reported in my Thanksgiving post for the North Anatolian Fault in Turkey), although I have not searched the scientific literature to see if that is actually the case here.

2. Note the aftershocks (orange circles) in the general vicinity of the main shock (star). They are not randomly distributed about the epicenter of the main quake, but are more linearly aligned, again parallel to the trench. So, the aftershocks also seem to be releasing some of the stress along the fault.

Stay tuned for more.