Time-Lapse Animation Shows Japan's Earthquakes

The magnitude 9.0 earthquake that struck off the coast of Japan on March 11 did not strike in isolation. For several days beforehand, as stress built up in the subduction zone plate boundary between the Pacific and North American plates, a series of significant temblors, called foreshocks, shook the area.
The magnitude 7.2 quake on March 9 was by itself larger than the Northridge earthquake of 1994, and at the time one of only nine events in the Japan trench subduction zone with a magnitude of 7 or higher since 1973.

Since the March 11 quake, the fourth largest in recorded history, aftershocks have continued to rattle Japan. A tsunami alert on Monday sent search and rescue teams running for high ground.