WASHINGTON - Senators from states most vulnerable to tsunami activity Monday introduced legislation to upgrade and modernize the nation's tsunami warning system.

Sens. Ted Stevens, R-Alaska, Daniel Inouye, D-Hawaii, and Maria Cantwell, D-Wash., said the bill would expand on a Bush administration plan to erect a tsunami warning system to protect the Pacific and Atlantic coasts by mid-2007.

The bill would authorize up to $35 million a year for the National Oceanic and Atmospheric Administration to upgrade tsunami detection and warning capabilities on the East and West coasts and Gulf of Mexico; expand tsunami research; and require NOAA to immediately repair malfunctioning tsunami-detection buoys.

Western lawmakers have complained that three of the six tsunami-warning buoys in the Pacific Ocean are broken. The greatest U.S. worry about tsunamis has been in the Pacific.

Stevens and Inouye are the chairman and senior Democrat, respectively, on the Senate Commerce Committee, which will consider the bill.

"Protecting human life and property from natural disaster requires the ability to reliably detect and forecast (tsunamis) ...," Inouye said. "The people of Hawaii and Alaska have long memories of the threat of tsunami." Both states have been hit by tsunamis.

The Dec. 26 Indian Ocean tsunami - the deadliest in the modern era - served as a horrifying reminder of the destructive power of seismic activity in the earth's oceans, lawmakers said. At least 160,000 people were killed, including more than 100,000 in Indonesia and at least 31,000 in Sri Lanka.

Cantwell, who toured NOAA's Pacific Marine Environmental Laboratory in Seattle Sunday, said the South Asia tsunami showed the United States is not fully prepared for a similar disaster.

Scientists at the marine environmental lab, which is developing tsunami-monitoring technology, said a buoy about 250 miles off the Washington coast has been malfunctioning for about 14 months.

"We're extremely concerned," Christian Meinig, an engineering division leader with the environmental laboratory, told Cantwell. "The bottom line is, we don't know why it's not functioning."

Meinig said a team of scientists from the National Data Buoy Center, another division of NOAA, repaired the buoy about two weeks ago, but the fix lasted just a few days.

The Bush administration announced a plan Jan. 14 to quadruple the size of the warning network in the Pacific and build similar protections for the Atlantic, Caribbean and Gulf coasts.

The administration plan envisions 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 Alaska coast.

Five new buoys would be installed in the Atlantic and two in the Caribbean Sea to provide coverage for the Gulf of Mexico. None now exist in those areas.

The proposed legislation would build on the administration plan and require NOAA to provide technical and other assistance to efforts to establish an international warning system for tsunamis.