The final result is a map of earthquake risk for any given location in California. The model shows the probability of earth movement that would be strong enough to throw objects off shelves. (The model does not calculate an earthquake's magnitude, which measures the energy contained in a quake.)
"Our ability to predict earthquakes remains very limited, but this research is a big step forward," said Thomas Jordan, director of the Southern California Earthquake Center at the University of Southern California in Los Angeles. "[I]t combines what we know about short-term and long-term earthquake probabilities to provide what is, for now, the best earthquake forecast for California."
The U.S. Geological Survey will continually update the 24-hour forecasts on the Web site.
The color coding of the map, showing the probability of severe shaking, goes from blue (small probability) to red (great probability). But most of the information in the maps has to do with aftershock sequences.
"You're not going to see red spots unless there's already been a large event," Gerstenberger said.
He hopes the forecast will be used as an educational tool.
"I don't see this as a weather forecast where people will look at it every day," he said. "But people can look at it and get a general idea of how the hazard works."
"By putting it in a visual format, we can remind the public that these things can happen," he added. "If they're somewhere with high probability, they may want to make sure they've done the standard things to be prepared for a quake."
The model could have important public-sector implications in the aftermath of a large earthquake, helping local authorities to coordinate rescue activities, for example.
In the future the tool may also be used outside California, in other earthquake-prone areas around the world.
"The model incorporates what we currently understand about earthquake forecasting," said Jordan, the Southern California Earthquake Center director. "Because it has been verified against data, it provides a new, more rigorous framework for assessing other earthquake-prediction experiments."
"In the scientific race to improve our ability to predict earthquake[s], it's the horse to beat," he added.
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