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Los Angeles has more to fear from these 'internal' quakes than the 'Big One' along the San Andreas. Although these faults are thought to be limited to M7.4, they are shallow, and right under the main population. I expect that they would go 'super' and put out a powerful PGV, perhaps even the legendary 'fling'.
A true velocity pulse fling would resemble the motions leading up to the crack of the whip. In that action, there is a low frequency pulse started, followed by a high frequency 'whip'. All these pulses combine at the tip to allow it to go supersonic. For an earthquake, the 'whip crack' is at the top of buildings, or even the top of the soil basin.
As well, with these earthquakes, we have the magical standing waves. These are waves that one can 'see' moving across the soil basin. Where they combine positively, all buildings are destroyed. Now, for years, witnesses to these waves were called delusional, since true seismic waves travel at a tremendous speed, which cannot be seen by the human eye. But these are not true seismic waves, they are a superposition of thousands of waves bouncing back and forth in the basin. At the surface, they can either appear stationary, as in a vibrating bowl of jello, or they can slowly migrate as the frequencies shift. Witnesses have noted paths of destruction, as these apparent waves passed.
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