PASADENA, Calif. – A powerful undersea earthquake off Russia's eastern coast on Monday caused automated monitoring systems to falsely indicate small temblors in Idaho and California, scientists reported.
The real quake had a preliminary magnitude of 7.3 and struck the Sea of Okhotsk 195 miles west of Petropavlovsk-Kamchatskiy, on Russia's Kamchatka Peninsula, the U.S. Geological Survey said. It was centered at a depth of about 300 miles.
That jolt caused computerized seismic stations in the western United States to send out false quake reports including a magnitude-4.8 quake in southeastern Idaho, a magnitude-3.8 in central California and a magnitude-3.4 at the Southern California mountain resort town of Big Bear.
The initial automated reports were accompanied by a standard caution saying they had not yet been reviewed by seismologists.
The false reports were deleted after seismologists reviewed the computer records, said geophysicist Julie Martinez of the USGS National Earthquake Information Center in Golden, Colo.
The Pacific Tsunami Warning Center in Hawaii said no Pacific-wide tsunami was expected.
A distant earthquake that is both large and deep can sometimes confuse faraway seismic stations, said Kate Hutton, a seismologist at the California Institute of Technology.
A scientist is always on call to verify a computer-generated report, she said.
"We know it's a problem," Hutton said.