ScienceDaily (July 10, 2008) — Using remarkably sensitive new instruments, seismologists have detected minute geological changes that preceded small earthquakes along California's famed San Andreas Fault by as much as 10 hours. If follow-up tests show that the preseismic signal is pervasive, researchers say the method could form the basis of a robust early warning system for impending quakes.
"We're working with colleagues in China and Japan on follow-up studies to determine whether this physical response can be measured in other seismically active regions," said Rice University seismologist Fenglin Niu, the study's lead author. "Provided the effect is pervasive, we still need to learn more about the timing of the signals if we are to reliably use them to warn of impending quakes."
Today's state-of-the-art earthquake warning systems give only a few seconds' warning before a quake strikes. These systems detect P-waves, the fastest moving seismic waves released during a quake. Like a flash of lightning that arrives before a clap of thunder, the fast-moving P-waves precede slower moving but more destructive waves.
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