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President George W. Bush signed a bill to upgrade and modernize the U.S. tsunami warning system Wednesday, almost two years after an Indian Ocean tsunami killed some 230,000 people in a dozen countries.

The legislation, approved by Congress earlier this month, is intended to bolster a tsunami detection and warning system in the Pacific Ocean, as well as expand it to any area in the Atlantic and Caribbean considered at risk by federal officials.

"The Indian Ocean tragedy reminded us of the need to have the best early warning and evacuation plan in place," said Rep. David Wu, who represents the Pacific coast state of Oregon.

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The law authorizes $135 million over five years to increase the number of deep-ocean buoys used to detect potentially devastating waves; requires certification of detection and monitoring equipment; and establishes a federal-state coordinating committee for tsunami detection.

Republican Sen. Ted Stevens said the law will provide important warning, information and education programs to help communities at risk of tsunamis. A 1964 earthquake and a tsunami that followed killed 131 people in Alaska, Stevens' state. The 9.2 magnitude quake was the strongest ever recorded in North America.

"Alaskans, more than most Americans, know firsthand the destruction tsunamis can cause. Just moving a quarter-mile (.4 kilometer) from the beach can save lives if people know to do it," Stevens said.

Democratic Sen. Maria Cantwell, also from a Pacific Coast state, Washington, said better and more reliable tsunami detection is critical for millions of people who live and work along that coast.

The 680-mile-long (1,095-kilometer-long) Cascadia subduction zone lies off the coasts of Washington and Oregon and is similar in size and geologic character to the fault that caused the 2004 Indian Ocean tsunami. The last major Cascadia quake occurred 300 years ago and hit the West Coast with an estimated 30-foot high ocean surge.

The U.S. Geological Survey estimates a 10 percent to 14 percent chance of another major Cascadia quake within the next 50 years. A tsunami generated in the subduction zone or in Washington's Puget Sound would allow for a warning of less than 20 minutes, which makes tsunami education and efficient evacuation plans essential, Cantwell said.

The Bush administration plans a network of 38 high-tech buoys attached to pressure recorders on the ocean floor. Twenty-five buoys would be added to the six now in the Pacific, including two as back-ups to existing ones off the coast of Alaska.

The new law builds on that plan and requires the National Oceanic and Atmospheric administration to help assess the vulnerability of coastal areas, as well as increase tsunami education and technical training in local communities.

For more on Tsunamis and other natural disasters, click here.