A deadly earthquake, one of the strongest ever recorded, struck Japan on March 11. The quake was followed by a tsunami along Japan's coast. Both events triggered tsunami warnings in coastal areas around the Pacific Ocean, including the west coast of the U.S. Douglas Wiens, PhD, Chair of the Department of Earth and Planetary Sciences at Washington University in St. Louis talks about earthquakes and tsunamis.

earthquaketsunamitidal wavefaultsseismology