I'm still looking at that strong motion data to see if I can learn to read it. So far it doesn't look too hard. Just need to understand the format and write some code.

But, back to your comment, the waves I saw couldn't have been more than a few hertz at most, 5 tops. What I saw wasn't fast. Although, taking into account the time compression effect of the human mind in moments of crisis, it was probably faster. So even 10-15 hertz tops.

Looking out across that parking lot, I don't think I saw more than a few waves, 5 tops. Probably about 2-3 full cycles. Hmmm...100 meter parking lot, 3 cycles, wavelength about 33 meters, 2km/s velocity... That's a frequency of 60 hertz... Now that *IS* a quandry.

Of course, that was back in 1987 so my memory is likely getting a few CRC errors.

Brian