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NOAA SAYS NO TSUNAMI THREAT FROM SEATTLE QUAKE
According to Tom Sokolowski, the Center's director, "The magnitude was too low to generate a tsunami." Before the Center issues a tsunami warning, an earthquake threshold has to exceed 7.0 on the Richter Scale and occur near coastal areas, Sokolowski said. Sokolowski said within two minutes after the earthquake occurred, the Center notified state emergency officials in the Pacific Northwest. "We told them that there was no chance of a coastal tsunami." A tsunami is a series of traveling ocean waves of extremely long length generated by disturbances associated primarily with earthquakes occurring below, or near, the ocean floor. Earthquake magnitude is measured based on calculations from ground motion recorded on seismographs. An increase in one full number means the earthquake's wave amplitude actually is 10 times greater. NOAA's
National Weather Service
has tsunami warning centers in Alaska and Hawaii, which monitor
all earthquake activity in the Pacific region. Through a program combining education and research, NOAA and its partners have increased public awareness of the risks of tsunamis as well as increased the scientific understanding on how these events behave. Computer simulations of potential and historical events give better pictures of areas that could be affected by tsunamis. Tsunamis can be caused by four things:1) large earthquakes, 2) landslides, both above water and underwater, 3) explosive underwater volcanoes, and 4) meteor impacts. Large earthquakes produce about 90 percent of the tsunamis. While most of the tsunamis occur in the Pacific Rim region, which includes the West Coast of the United States, Hawaii, and Japan, researchers recently discovered indications that there had been slumping on the U.S. East Coast, which, if conditions were right, could cause an event in that part of the country. On the West Coast, there is the Deep-ocean Assessment and Reporting of Tsunamis (DART) system, a series of buoys from Alaska to California, that can sense a shift in the water and send an alert to NOAA's West Coast and Alaska Tsunami Warning Center, an integral part in early warning should a tsunami occur. Computer models help "picture"
where water would go in such events and the areas affected. The
NTHMP is using this information to prepare inundation maps for
states bordering the Pacific Ocean. This information will help
emergency managers plan for an event.
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