The Most Damaging Type of Earthquake Wave for Buildings and Engineering

Multiple Choice

The most damaging type of earthquake wave for buildings and engineering structures on top of the ground is a surface wave with horizontal motion back and forth parallel to the passing wave front. Which description fits this type of surface wave?

A) The little parcel of rock rotates about its own location in an ellipse until the wave passes.
B) The rock moves toward and away from the earthquake as the volume of the material alternately expands and contracts, changing the rock's density while the compression- rarefaction wave passes through.
C) The little parcel of rock shimmies from side to side as the wave passes, with the greatest motion at the Earth's surface, dying out with depth.
D) The volume of the rock stays fixed, but it shears back and forth, distorting the rocks internal shape as the wave passes through.