Yo, Dennis, etal,

It would seem reasonable that any angle would increase the pressure necessary to cause fracturing of a rock. If the rock was sedimentary in charachter, then perhaps an angular pressure would be MORE efficient, depending on the alignment of the grain compared to the force.

Do you consider the angle of the fault (with hindsight) to coorelate with the strengths of your siggnals? That's not possible in 3 dimensions with some of these, but at least in 2 for nearly all cases.

Hard to think about this without knowing what frequencies you are watching, you know?

Al