Some deep sea quakes send warning signals

LOS ANGELES, March 24 (UPI) -- Earthquakes along Pacific Ocean fault lines emit small "foreshocks" that can be used to forecast the main tremor, a report says.

It's the first demonstration that some types of large imminent earthquakes may be systematically predictable on time scales of hours or less, according to research in Thursday's issue of Nature.

Statistically reliable forecasting of imminent quakes has been an elusive goal for seismologists.

Co-author Thomas Jordan, director of the Southern California Earthquake Center, stressed quakes on land generally do not show many foreshocks and cannot be predicted with the methods outlined in the Nature paper.

The research team, led by Jeffrey McGuire of the Woods Hole Oceanographic Institution, studied past earthquakes along two so-called transform faults on the East Pacific Rise, where tectonic plates are spreading apart. Sensor data from the National Oceanic and Atmospheric Administration pinpointed the time and location of foreshocks and earthquakes.