Hoping to protect U.S. shores from being hammered by a tsunami, the White House directed federal agencies Friday to increase earthquake and volcano monitoring systems, deep ocean buoys and other high-tech means of alerting oceanside communities.

The tsunami plan was requested by President Bush and Congress after an earthquake on Dec. 26, 2004, caused a massive tsunami in the Indian Ocean. It killed or left missing at least 216,000 people in 11 Indian Ocean countries, and "demonstrated international vulnerability," said John Marburger, Bush's top science adviser.

"Tsunamis are low probability but high impact events," he said.

The tsunami rose a massive 30 feet. Sumatra was the hardest hit, losing some 128,000 people. But the great wave also traveled around the world, and was recorded as far away as Peru and northeastern Canada.

Marburger, who directs the White House Office of Science and Technology Policy, said U.S.-led improvements in tsunami detection and warning since a year ago made people safer at home and work, and the new plan will further reduce risks to life and property. Congress appropriated $24 million in May for a better U.S. tsunami system.

An international tsunami expert, however, said more high-tech warning buoys won't make a difference unless more cities and towns prepare, so people know where to seek shelter. He also urged more land-use planning to avoid building schools and hospitals near ocean shores.

"If we're talking about saving lives, we're really talking about preparing local communities," said Harry Yeh, a professor of civil and environmental engineering at Oregon State University in Corvallis. "When a tsunami happens, it will take 30 minutes or less. So how you can rely on a top-down official warning system from the buoy? ... Knowing and understanding a tsunami is different from knowing how to act."

Specifically, the plan written by the president's National Science and Technology Council directs federal agencies to:

—Develop risk assessments of the potential tsunami hazards for all U.S. coastal regions.

—Increase the number of tsunami buoys, tide gauge and seismic sensors feeding real-time data into computer models to improve tsunami forecasting and warning systems along Pacific, Atlantic, Caribbean and Gulf of Mexico coastlines.

—Give technical help to improve warning systems for tsunamis and other hazards in the Indian Ocean.

—Encourage communities to develop tsunami response plans, and to build and plan in ways that can reduce the impact of a future tsunami.

In the past year, scientists at the U.S. Geological Survey and the National Oceanic and Atmospheric Administration have led efforts to expand the U.S. tsunami detection network.

NOAA Administrator Conrad Lautenbacher has pushed to grow the network from six to now 10 tsunami buoys. Located off the Aleutian Islands, the Washington and Oregon coasts and South America, the buoys send warning signals if they sense a change in sea level.

That network was first developed more than a half-century ago. In 1946, a tsunami starting in the Aleutian Islands struck Hawaii, killing more than 150 people. In response came Hawaii's warning system and, in 1949, its Pacific Tsunami Warning Center.

More recently, NOAA has designated 24 U.S. coastal communities in Alaska, California, Florida, Hawaii, Oregon, and Washington as "Tsunami Ready." Those places have voluntarily developed emergency plans, with evacuation routes to a shelter outside the hazard zone.

NOAA also spent $4.6 million to improve warnings against tsunami and other hazards for India, Sri Lanka, Indonesia, Thailand and the Maldives. The U.S. Agency for International Development spent $656 million in humanitarian aid such as food and medical supplies, transportation and refugee assistance in the Indian Ocean region.

Yeh said U.S. preparations must become habitual — and perhaps mandatory — if they are to be effective.

"If it's voluntary, five years from now it's gone. There's no pressure. You have to have a string attached," he said. 'We really need to think about what we can do to maintain tsunami readiness at the local level, because a tsunami is not going to happen so often."