24829: Hermantin (News) Tsunami threat high in parts of Caribbean

[sak-pase@bimini.ws]

leonie hermantin <lhermantin@hotmail.com>

Tsunami threat high in parts of Caribbean
By MIKE WILLIAMS
Cox News Service
Monday, April 18, 2005

MIAMI — The landscapes are half a globe apart, but eerily similar: dazzling 
tropical islands curve in graceful arcs across azure seas, while simmering 
volcanoes jut skyward and deep ocean canyons furrow the ocean bed just 
offshore.

Scientists say the similarities between parts of the Caribbean basin and the 
Indonesian island chain are no coincidence: both are tectonic pressure 
points where the earth's crustal plates jam together, spawning unimaginable 
pressures.

Caribbean residents, they warn, should take heed from the deadly Asian 
tsunami that stunned the world and killed more than 170,000 people in 
December, because the very same forces are at work in their own backyards.

Six tsunamis, with documented loss of life, have struck in the northern 
Caribbean area since Columbus landed, said Nancy Grindlay, a geologist at 
the University of North Carolina at Wilmington who studies the region.

Caribbean scientists are all too aware of the threat — and the fact that 
they currently have no tsunami warning system in place. They are pushing to 
create such a system, hoping it would give residents a chance to scramble to 
safety before the giant waves rushed ashore.

"Our problem is very serious," said Victor Huerfano, a researcher at the 
Puerto Rico Seismic Network, based at the University of Puerto Rico in 
Mayaguez. In 1918, he said, an earthquake off the western part of the island 
sent a 20-foot wave to shore just five minutes later, killing 35 people 
according to the official tally. "The numbers were probably higher."

Even though the American mainland is about 1,000 miles away, the biggest 
Caribbean dangers happen to lie just offshore Puerto Rico, a U.S. 
commonwealth, while the nearby U.S. Virgin Islands are also at risk.

But in a region of small, mostly poor islands, that accident of geography 
may be fortunate. Wary of the recent Indonesian disaster, the Bush 
administration has approved an expansion of an existing monitoring system, 
adding sophisticated buoys that will provide tsunami warnings for the most 
threatened parts of the Caribbean.

"After the Dec. 26 event, the agency recognized the need to implement a 
warning system for the U.S. east coast," said Theresa Eisenman, a 
spokeswoman for the National Oceanic and Atmospheric Administration. She 
said the administration has committed $35.7 million for the warning system, 
to include seven buoys that will be stationed in the Atlantic and the 
Caribbean.

Other new buoys will be stationed in the Pacific Ocean, where the risk of 
tsunamis is also very high, particularly in Alaska and Hawaii.

The Caribbean hot spot lies just north of Puerto Rico and the island of 
Hispaniola, which is home to both Haiti and the Dominican Republic. Beneath 
the ocean, the Puerto Rico Trench dives to a depth of some 27,000 feet — the 
deepest spot in the Atlantic, comparable to the depth of the Java Trench 
just off the Indonesian coast.

The deep undersea valleys are the places where the earth's crustal plates 
collide, with one gigantic mass diving beneath the other. The plates 
normally move only millimeters per year, but the slow, inexorable grinding 
generates tremendous amounts of pressure.

The pressure builds until, with a jolt, the plates move dramatically. The 
result is an earthquake, in which huge sections of the sea floor can shift, 
sometimes causing undersea landslides that generate giant waves, or 
tsunamis.

Fortunately for U.S. residents, the threat to the American mainland is not 
as dramatic as that facing the Caribbean islands. Florida's east coast, 
scientists say, would likely be spared from major tsunami damage should a 
quake occur near Puerto Rico, because the Bahamas would block most of the 
waves.

The danger in the Caribbean, however, is very real. The region is home to 
about 30 million residents, many of whom live packed along their coastlines.

The last tsunami in the area came in 1946, when an earthquake struck in the 
ocean south of Hispaniola. It generated a wave approaching 40 feet in 
height, which slammed ashore and killed about 1,700 people in the Dominican 
Republic.

Puerto Rico's Seismic Network currently has land-based monitoring stations 
that record earthquakes, but no ocean-based sensors other than tidal gauges. 
Scientists there welcome the Bush administration's proposal to add buoys in 
the Atlantic and the Caribbean.

The buoys, which should be deployed in the next two years, are tethered to 
ocean-floor devices that sense changes in water pressure created by 
tsunamis. The readings are automatically relayed to monitoring stations via 
satellite. The Puerto Rican agency is already tied in with the existing NOAA 
tsunami warning system, and the new information from the buoys will be 
quickly transmitted to the island.

Puerto Rican officials also have flood maps — which federal officials are 
updating — that predict how high the surge from tsunamis would reach. They 
hope to bolster an education program that will warn residents of low-lying 
areas what to do in case of an earthquake and tsunami.

The basic message is to run for higher ground, something that seems simple, 
but as news footage from the Indonesian disaster proved, isn't necessarily 
the immediate reaction of people caught by surprise as a giant wave rolls 
toward them from the ocean.

But even with the warning system in place, Puerto Rican officials worry 
about offshore fault lines that are just a few dozen miles from the island.

"There will be very little time between the earthquake and the arrival of 
the tsunami," Huerfano said.

Paul Mann, a senior researcher at the Institute of Geophysics at the 
University of Texas at Austin, has also studied the region alongside 
Grindlay. He points to the presence of large slump areas along the Puerto 
Rico trench which appear ripe to become undersea landslides should a major 
earthquake happen.

"Some of them look very unstable," he said. "They are capable of creating a 
large tsunami should the material be displaced."



On the Web:

NOAA public domain artist renderings of the buoys and their 
locations:www.noaanews.noaa.gov/stories2005/s2369.htm


Mike Williams' e-mail address is mwilliams(at)coxnews.com