San José, Costa Rica, since 1956

Huge Waves Have Struck Region

THE most devastating tidal wave tostrike Central America hit the Pacific coastof Nicaragua in 1992, a 9.5-meter wavethat left approximately 170 dead and morethan 500 people injured (TT, Sept. 4,1992).The giant wave struck by night, half anhour after an earthquake measuring 7.0 onthe Richter scale hit 100 kilometers southwestof Managua, Nicaragua.Since 1539, 49 tidal waves have beendocumented in Central America, only nineof which have caused significant destruction,collectively killing a reported total of455 people. However, the number ofdeaths and tidal waves could be largerbecause of reporting difficulties centuriesago. The Pacific coast has been the hardesthit, weathering 37 big waves while 12 havehit the Caribbean.GUATEMALA and Nicaragua appearat the highest risk for tidal waves, judgingfrom the number of past occurrences in thearea and the destruction they have leftbehind. In 1902, for example, a tsunami inGuatemala and El Salvador killed 185 people(TT, Sept. 3, 1999).Fifteen small tidal waves created byearthquakes have struck Costa Ricanshores, five on the Caribbean coast and 10on the Pacific, according to a study byMario Fernández, coordinator of theCentral American Seismological Center ofthe University of Costa Rica.The most destructive wave demolishedVilla Golfo Dulce in the southern Pacificzone in 1854, caused by a magnitude 7.3earthquake.The 1992 Nicaragua wave lappedagainst Costa Rica’s northern Pacific coastbut caused little damage there, mostly toboats and bridges.TIDAL waves often are calledtsunamis by both Spanish and Englishspeakers. It is a Japanese term derivedfrom the roots tsu (harbor) and nami(wave), an expression used to describeenormous waves that struck ports afterearthquakes.Spanish speakers also use the termmaremoto, which denotes the movementof the sea (mar), and linguistically linksthe event to significant earthquakes,called terremotos.Tsunamis result from an imbalance inocean waters generated by abrupt disturbanceson the marine floor resulting fromvolcanic eruptions, underwater landslides,meteorite impacts or earthquakes, usuallyof magnitude 7 or higher.Along the Pacific coasts, 43% of earthquakesof magnitude 7 or higher have createdtidal waves, and 100% of quakes thatsize in the Caribbean have created tidalwaves, Fernández reported.

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