Lowell suggested P and S wave triggering well before 1992. Then, the M 7.4 (?) Landers earthquake occurred and there was P and S wave triggering at least as fas as Long Valley-maybe as far as Yellowstone. Large underground tests can have magnitudes up to about 5.5 So, I think some limited triggering from an underground test is plausible. But, Don pointed out fallout-I'd say dead southern Asians and the bad precedent would be other concerns....I would not worry about a cascade of earthquakes. Chris