Structural damage from seismic vibrations would be worse where buildings were built to code on solid rock where older buildings were built on a thick layer of sediment where the focus is about 800 kilometers below the surface where buildings are made mostly of wood

The answer to this question is the second item in the choices which is "where older buildings were built on a thick layer of sediment". We know that seismic vibration is the sound or movement generated from the ground. This happening is unwanted and cannot be controlled. Once this occurs in higher magnitude it would cause great damage to our structure were buildings made of rock collapse. 

Нет, нужен трамвай, аэропорт, приют. я предлагаю обществу общественной помощи.

Bcold,less-dense air falls