Stanford pair say they have created more precise quake-predicting system

In the seismically unpredictable Bay Area, Stanford scientists say they have developed a system that would better estimate the likelihood of the next major temblor.

Experts say earthquakes are difficult to predict because of the lack of understanding of the physics of earthquakes. However, two Stanford scientists have developed a formula that can better predict how big Bay Area earthquakes can be and how frequently they can occur.

According to professor Paul Segall of Stanford University and Stanford graduate and Indiana University assistant professor Kaj Johnson, earthquake data collected during the last decade focused on how fast faults are slipping, but failed to place emphasis on the rate at which faults are failing.

“The data collected over the past 10 years tell us how fast faults are slipping, and if we know that rate, we could better predict how big and how frequent [an earthquake] might be,” Johnson said.

The Bay Area’s last major quake, the Loma Prieta earthquake, which occurred Oct. 17, 1989, was a magnitude of 6.9 that collapsed the upper deck of the Bay Bridge and killed 57.

In a presentation given during the American Geophysical Union conference at Moscone Center on Thursday, Segall and Johnson unveiled the formula they’ve been working on since 2003, and that, they say, bridges the gap between traditional and modern methods of forecasting.

Geophysicists use two systems of measurements that often give differing views of the likelihood of a movement along a fault line. Global positioning satellite technology makes minute measurements on how fast an earthquake fault has been displaced. The other system studies the imprints on rocks and sediment of known fault lines to measure the frequency and magnitude of past temblors.

Johnson said the mathematical model he and Segall developed will “plug in” the combined data sets to a formula to precisely map how quickly faults move during the different stages of earthquakes.

“This is something people had been asking for years now,” Johnson said. “It’s the next step.”

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