focal mechanisms give 2 planes
Posted by heartland chris on August 01, 2008 at 06:05:03:

Canie, Focal mechanisms give 2 planes...if one is right-lateral the other is left-lateral. Which one is the actual fault is given by other means..for example, which one aftershocks line up along (or ground rupture). There are probably ways to tell which one was the quake remotely...John would know...probably would work better for larger quakes.
The summary discusses why they chose the left-lateral plane (the other they call "auxiliary".
Chris