@edgarblythe,
I've wondered about this before, in that case it was about tornadoes, I think. I'm used to California construction, which is earthquake wary; there is, or was, a lot of use of Simpson steel tie connectors there in building. My observations about the construction industry in New Mexico leave me with a lot of negative opinions, but those are just spotty observations these days.
Reading about the houses collapsing along the Blanco River, I can see water destruction wherever that overflowing happened in any state or country, but I'm perplexed that the framing went down so fast. I get it that it's the force of the water, but still wondering that some frames didn't retain shape. Aren't they tied to the slabs, etc. ? Did the slabs float too?