Deep-sea tremors

Predicting when large earthquakes might occur may be a step closer to reality, thanks to a new study of undersea earthquakes in the eastern Pacific Ocean.

The study, reported in Nature, is the first to suggest that small seismic shocks or foreshocks preceding a major earthquake can be used in some cases to predict the main tremors.

Scientists from the Woods Hole Oceanographic Institution (WHOI) and the University of Southern California (USC) report that some types of large undersea earthquakes may be predictable on time scales of hours or less. Earthquakes on land are generally not preceded by systematic immediate foreshocks and hence cannot be predicted as easily with the same methods.

The research team, led by Jeffrey McGuire of WHOI, studied past earthquakes along five transform faults on the East Pacific Rise, where tectonic plates are spreading apart at a rate of more than ten centimetres or five inches a year. The team used data from sensors deployed by the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory that pinpointed the time and location of foreshocks and the mainshocks or larger earthquakes.