What happens to man-made structures during an earthquake?

It really depends on how earthquake-hardened they are. In recent decades, a great deal of research and development has gone into developing and building more earthquake "proof" structures. These can include the introduction of shocks or struts to the foundation of the building that reduce or counter the swaying action of quakes.

The biggest element to consider is that the more rigid less flexible a structure is, the more it is susceptible to damage or destruction from a quake. This is the primary reason from vast areas of devastation in third world, and old world regions where quakes occur. Mortar and plaster constructions do not hold up well when the ground shakes.