Five great earthquakes of M9 or larger have been recorded in the past century and each was followed by a major tsunami, along with vast devastation and many deaths. These events have provided information to help mitigate the effects of future great earthquakes - including what to keep in the back of your mind if you experience strong earthquake shaking in coastal areas worldwide.
When an M8.2 earthquake struck offshore of the Alaska Peninsula on July 28, the eerie sound of sirens warning of a possible tsunami sent people along the coast scrambling for higher ground. Authorities lifted the warning within a few hours, and damage from ground shaking was limited. Viewed from a broad perspective, this event was only a minor distraction, but many earthquakes that are this powerful result in major disasters.