Tsunami alerts help save lives - USATODAY.com

Three hours after an earthquake struck Chile, a sensor on the ocean floor 205 miles from the epicenter registered the first inkling that a tsunami was traveling across the Pacific toward Hawaii.

As data poured into the Pacific Warning Center of the National Oceanic and Atmospheric Administration (NOAA), scientists calculated how far the tsunami would travel and how powerful it would be when it arrived at the world's coastlines, ultimately issuing a warning for Hawaii and an advisory for the U.S. West Coast...