USGS: Study of Japan earthquake helps predict future risks

Wednesday - 3/16/2011, 2:49pm EDT

Gavin Hayes, geophysicist, U.S. Geological Survey

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Days after the devastating earthquake in Japan, the U.S. Geological Survey updated the magnitude from 8.9 to 9.0, making the earthquake the fourth largest ever recorded.

To put the change in perspective, a 9.0 magnitude earthquake is 30 times bigger than a 8.0 magnitude earthquake, said Gavin Hayes, a geophysicist at USGS, in an interview with the DorobekINSIDER.

Independent from the USGS change, Japanese seismologists also updated their estimates of the earthquake's magnitude to 9.0.

Hayes said in large earthquakes like the one in Japan, the time it takes for energy to "propagate and stabilize" can be longer, which means it takes longer for seismologists to estimate the magnitude.

The academic community will continue to study the earthquake, particularly what part of the underwater fault moved, Hayes said. This analysis can help predict where the next earthquake might be, he added.

"For instance, we wouldn't expect a magnitude 9.0 earthquake on this same part of the fault, but adjacent parts of the fault that didn't move in this earthquake are probably at higher risk for moving in future earthquakes," Hayes said.