The tsunami that rocked the eastern coast of Japan on March 11 of this year was captured by high-frequency radar in California and Japan as it rocked in from the epicentre of the earthquake. This is the first time that a tsunami has been picked up by radar and raises new possibilities for the early detection of tsunamis.
Professor John Largier is an oceanographer at the University of California, Davis, Bodega Marine Laboratory and an author of a paper that looks at the capture of the Japanese tsunami that appears in this month’s issue of the journal Remote Sensing.
“It could be really useful in areas such as south-east Asia where there are huge areas of shallow continental shelf,” said Largier, who along with his colleagues at the Bodega Marine Lab have been using high-frequency radar to study ocean currents for the last 10 years.
Togeher with collaborators from Hokkaido and Kyoto universities in Japan and San Francisco University in the States, Largier used data from radar sites at Bodega Bay, Trinidad, California, and two sites in Hokkaido, Japan, to look for the tsunami before it reached the coast.
The scientists found that, while they could not pick up the actual tsunami wave itself, which is small in height while it’s out at sea, they were able to find evidence of the tsunami once it entered shallower coastal waters over the continental shelf.
The continental shelf off the California coast is quite narrow, and is already well-monitored by pressure gauges. But for locations such as the East Coast of America or Southeast Asia, radar detection could be a good way to provide an early warning system for tsunamis.