Pre-quake changes seen in rocks

Scientists have made an important advance in their efforts to predict earthquakes, the journal Nature says.

[Bairn of Ecgtheow]

I guess that there could be increased or decreased stress recorded depending upon which way the rock is bending. Concave and you have tighter rock, faster seismic signals, convex and you have looser rock with more fractures, so slower signals. So I guess it depends upon which side of the San Andreas fault you are on.