On Guam
I was visiting there via the Navy and we were in this old rundown concrete barracks structure that I'm sure was built long before any earthquake construction standards were created and there was this massive single jolt and a huge "thump" to go along with it. The Earth just went up and down once. None of us had any idea what had just happened. We slowly figured it out.
I later learned that thump was worth 7.9 on the scale. Had it had any duration at all to it, we'd have been mushed below the upper floor of that old barracks. What a learned that day was things like that can come without warning, and if severe enough, would give you not even enough time to say some prime cuss word.
Art