China Earthquake

A very tiny earthquake M5.6, but shallow, in a mountainous area.  This was most likely a thrust fault, resulting in a high PGV.  This is a very active area, and there are landslides all the time.  Combine this with a high population density, and you get a mess.

With boulders falling, and unstable ground, I doubt you could even build a resistant house, but probably most housing is poorly made.