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Earth-shaking developments

Researchers suggest that they may have found a way to map the epicentres of ?silent earthquakes?.
None | By HT Correspondent
PUBLISHED ON JUL 31, 2006 12:08 AM IST

Are we any closer to predicting earthquakes? Seismologists must be asking this question after Nature published the results of a study last week, by researchers in the University of Tokyo and Stanford University, that suggest that they may have found a way to map the epicentres of ‘silent earthquakes’. These tiny tremors deep inside Earth produce no tell-tale seismic waves. But over time, they build up enough pressure on the  Earth’s crust to force it to twitch violently in a major quake. The researchers apparently discovered how these hushed tremors are linked to low-frequency earthquakes (which last for over an hour and can be monitored). The scientists believe they can tell where silent quakes are building up pressure.

Although these findings are remarkable, predicting individual quakes is still not a realistic scientific goal. Far more research is needed before geoscientists learn what triggers low-frequency quakes, and corresponding silent quakes. Earthquakes occur when the assemblage of plates on Earth’s surface grind   against each other, causing ‘faults’ in the planet’s crust. A patch of the crust sliding along a fault can slip suddenly to release energy waves that result in an earthquake. Even though a great deal is known about where the earth is likely to quake, there is still no way to predict when. A good bet may be to study the spatial patterns of the world’s largest tremblers to forecast the locations and magnitudes of potential quakes, if not the time. For instance, strain builds up where Earth’s crust deforms over time. These deformations are good indicators of imminent quakes and can be detected by hi-tech radars on satellites.

That said, it might never be possible to predict the exact time a ‘biggie’ could strike, because when a fault becomes unstable, any small background tremor can hasten the rupture.

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