A massive earthquake triggered fears of a tsunami after police posted a dramatic message on Facebook. It started after the 7.9-magnitude quake struck 180 miles off the coast of Kodiak, Alaska. The entire West Coast was placed under a tsunami watch. For three hours before it was called off, people braced for the worst. The world saw the power of a deadly tsunami after one hit Japan following a 2011 earthquake. In that tsunami, sidewalks turned into rivers and buildings were smashed to pieces.