The March 11 earthquake off the coast of Japan and the resulting tsunami that devastated so much of the country’s coastline have served as a reminder that such events can happen in just about any coastal area. The US National Oceanic and Atmospheric Administration (NOAA) has declared this “National Tsunami Awareness Week” and has issued reminders for those in coastal regions about what to—and not to do—if one is imminent. It’s worth taking a look at the system, developed over many decades, that lets us know we might be in danger.
DART (Deep-ocean Assessment and Reporting of Tsunami), a system of sea-floor sensors and moored buoys, provides real-time detection of a tsunami in the making. During an earthquake, seismic data are transmitted from the bottom sensors to the buoys. These relay the information, along with sea-level measurements, to satellites, which in turn alert ground stations. The system can determine the coastal locations likely to be affected and the height of the waves that might reach them.
This article from the San Francisco Chronicle details the development of the system, from the 1920s in Hawaii to today. About six detection buoys were in place before the Sumatra-Andaman earthquake in the Indian Ocean, which caused the devastating Asian tsunami in 2004; now there are 39 of them, deployed by countries around the Pacific Rim. Because of the system, on March 11 NOAA was able to warn officials on the West Coast of the US, just 12 minutes after the earthquake occurred in Japan, that a tsunami was on the way. DART also provides coverage for the Indian Ocean, South China Sea, Caribbean, Puerto Rico, and US Virgin Islands.
On Wednesday, March 23, 33 countries will participate in a full-scale tsunami alert exercise in the Caribbean, testing the effectiveness of the various governments’ warning systems. During the exercise, the countries will receive notice of and respond to a fictitious 7.6 magnitude earthquake off the coast of the US Virgin Islands.
NOAA has additional tsunami resources available online: www.erosioncontrol.com/the-latest/noaa-tsunami-resources.aspx.