Even a small shaker may cause the speakers to slide on the sharp points, thus causing scratches that will immediately decrease the value of the speaker by more than half.
As you know, I'm up in Seattle, right next to a fault line. I've lived through a couple of shakers myself - one pretty good one where I stood in the door frame of my studio (not enough time to get out) and watched the walls undulate and the floor go up and down (what a truly bizarre sight). No damage to spiked components in my systems that I recall. I'd guess you could speculate on all kinds of risks to your speakers and system. Things could fall down on it, they could fall on any stand you choose, pipes could break, fires could start. Heck, you may not make it through to enjoy your speakers. Life's too short. Isolate freely and without fear. You could always hang them by cables from the ceiling once you've determined the best position (that's a serious suggestion).