VRML of earthquake hypocenters (represented by green spheres) centered around the Owen's Valley in California (created by David Valentine, UCSB.) This oblique view shows that earthquakes have a third dimension, depth, that is not shown in two dimensional drawings. The hypocenter is the exact location where the fault moved. This is almost always below the ground surface.

This is the same VRML as the top figure, except the perspective has been rotated to a nadir or birds-eye view. This shows how hypocenters translate into epicenters. The epicenter is the point on the surface of the Earth directly above the hypocenter. Ignore the red and blue data for now.