Tsunami: triggers expanded warning system

Boat/US Magazine, March, 2005 by Dick Thompson

In the aftermath of the Dec. 26th Indian Ocean tsunami more than a few boaters have wondered: could it happen here and what would I do if it did?

Some residents of Hawaii and Alaska, as well as the Pacific Northwest, have experienced a tsunami, but few communities in the United States have warning systems or action plans ready on how to respond. Only in the eastern Pacific is there a system of sensor buoys in place to warn of a tsunami and, as currently set up, was no help to those in the Indian Ocean.

Riding It Out

For world cruisers, the remote possibility of being caught in a tsunami became quite real on December 26th.

One first-hand account affirms that riding out a tsunami on a boat may be the best course of action--if the boat can get out of the marina in time. Past events and science show that the deeper the water, the less effect the tsunami has. In fact, ships at sea may not even feel a tsunami as it passes beneath their hull.

Details in an e-mail from Dick and Leslie York, who have been sailing their J-46 Aragorn around the world and were in Thailand when the tsunami hit, proves that sticking with your boat is the safest option even if you can't get far offshore.

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"We successfully weathered the wave. We were blessed, as were most of the rally boats," said Dick York. "Many of us were in a small cove, with about 12 boats on the north side of Phi Phi Don Island. The wave sucked the water out of much of our cove, and then filled it up again. At the same time, the wave was pouring over the sand spit. It did this at least three major times. The water in our small, circular bay was spinning, making boats look like a Disneyland ride," he said.

York went on to say, "The water rushing out made a giant spinning pool, anti-clockwise, clear on the edges and brown in the center. Boats just inside us were being pulled around in this circle. Two boats in our group and one or two non-rally boats broke their anchor chains, and spun loose."

"At the same time we were being pulled hard backward toward the sea, so I started the engine and ran it in forward. I had all hands don the large life jackets and we tried to get the anchor up. The boat turned 180 degrees around our chain at least once as the wave began to flood the bay ... The anchor finally came up, and we exited as fast as we could. I think the wave was on an ebb about then, but it is hard to tell in the crazy quilt of the moments."

Pacific Warning System

The first tsunami warning system, near Honolulu, HI, was created in 1949 as a result of the tsunami generated by a 7.1 magnitude earthquake in the Aleutian Islands in 1946. That tsunami struck the Big Island of Hawaii on April 1st and flooded the downtown area of Hilo killing 159 people and destroying more than 1,700 homes. Unfortunately, this modest system of tide buoys and seismographs failed to detect a 1960 tsunami originating in Chile and Hilo was hit again with waves over 35 feet high killing 61 people.

The world's only accurate detection system today is spread along the three major underwater fault lines in the Northeastern Pacific Ocean. It was conceived following a 1964 earthquake that measured 9.2 on the Richter scale. The resulting tsunami hit Alaska, the U.S. West Coast and British Columbia causing 106 deaths in Alaska, four in Oregon and 12 in California, and did hundreds of millions dollars in damage. Even so, a fully operational system was not put in place until 2003.

The system consists of six buoys that make up the Pacific Deep-ocean Assessment and Reporting of Tsunamis (DART) program--three off the Aleutian Islands, two off the West Coast and one near Hawaii. These buoys provide real-time data to the National Oceanic and Atmospheric Administration (NOAA) centers in Alaska and Hawaii from data transmitted by satellite and can warn communities within minutes of a potential tsunami. The West Coast Alaska Tsunami Warning Center in Palmer, AK, serves as a regional warning for Alaska, British Columbia, Washington, Oregon, and California, whereas the Pacific Tsunami Warning Center in Ewa Beach, HI, provides tsunami warning information to 26 participating nations in the Pacific Basin--unfortunately, none in the Indian Ocean so devastated in December.

After notifying affected nations, NOAA provides direct broadcast of tsunami information to the public from their VHF transmitters, and the U.S. Coast Guard broadcasts urgent marine warnings to coastal users equipped with medium frequency (MF) and VHF marine radios. Because tsunamis often travel great distances, early detection can provide hours or more warning time for people to evacuate a shore area.

Beyond the Pacific

Could a tsunami happen along the U.S. East Coast, Gulf of Mexico or Caribbean? Data from NOAA shows that 50 tsunamis have hit the Caribbean in the past 150 years and over 30 have occurred in the Atlantic. In fact, since records have been kept, tsunamis have caused more deaths in the Caribbean than in Alaska, Hawaii and the East Coast combined. Some 40 people died from a 20-foot tsunami caused by an earthquake in the 5.2-mile-deep Puerto Rico Trench (the deepest location in the Atlantic Ocean) within the Mona Passage north of Puerto Rico in 1918.