July 25, 2005— Tidal gauges in the Indian Ocean detected the deadly tsunamis last year and could have saved lives if they had been better equipped to get out the word, say researchers.

The Dec. 26 tsunami was recorded by a network of tidal gauges in the western Indian Ocean that are part of national and international efforts to observe how sea levels are changing in response to global warming.

The tsunami has shown that with some modest changes, the same gauges, and others being planned, could easily become part of an ocean-wide tsunami warning system, said the researchers involved in building the network.

They made their case in a recent issue of Geophysical Research Letters.

"We've been doing monitoring and trying to strengthen the network," said Mark Merrifield of the University of Hawaii. "We've been trying to find a way to link with hazard groups," he said.

The Indian Ocean tsunami not only revealed such a link, but it pointed out some very specific changes the gauges will need to accomplish the tsunami-watching task.

For one thing, the gauges need to take more measurements, said Merrifield. Currently some gauges take as few as one measurement each hour, which runs the risk of missing the rise and fall of a passing tsunami, Merrifield said.

"We also need to transmit that data," he said. That means using telecommunications satellites to upload information from remote ocean sites and relay the info to the world.

The warning system could also help determine when a tsunami has not been created by an undersea earthquake, which is fairly common.

A good example, said Merrifield, is what happened in the recent tsunami alert on the north coast of California. A powerful earthquake offshore created a potential for tsunamis. So people acted on it.

"You make the warning," said Merrifield, "and then use the gauges to call off the alarm" when nothing is detected, Merrifield explained.

The Pacific Ocean is already equipped with a network of gauges that form a tsunami warning system.

"Upgrading of the tidal station network in the Indian Ocean should be encouraged," said tsunami researcher Patrick Lynett of Texas A&M University. "Tidal stations are relatively cheap, accessible, and as shown, very good recorders of near-shore tsunami waves."

It seems reasonable, said Lynett, that an upgraded tidal gauge system, used along with a few strategically placed deep-water sensors, may be the best detection system for the Indian Ocean.