LONG BEACH : Scientists Begin Search for Quake Faults in Ocean

Scientists on the research vessel Maurice Ewing began firing bursts of air into the ocean Thursday in an experiment to try to find hidden fault lines such as the one that caused the Northridge quake.

The U.S. Geological Survey and the Southern California Earthquake Center are co-sponsoring the experiment.

Air bursts from a battery of guns placed 30 feet below the surface will be fired every 20 seconds for the next eight days. The boat from which the bursts are fired will be miles offshore, so residents will not hear the blasts.

“These bursts of air will generate seismic waves in the water, which will, in turn, enter the earth at the bottom of the ocean and will propagate through the earth much as X-rays would propagate through your body from an X-ray source,” scientist Tom Henyey said. The waves “will be picked up on land with receivers in the L.A. Basin, the mountains and as far away as the Mojave Desert.”

The receivers are arrayed in three separate lines that wind throughout the basin. One extends from Santa Monica through Northridge to the western Mojave. Another begins in Redondo Beach, and ends in Colton; the third goes from Seal Beach northeast to an area near Barstow. A similar experiment in Northern California found several faults.