IMAGES: Tune In for the Quake Cast

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Science  27 May 2005:
Vol. 308, Issue 5726, pp. 1233
DOI: 10.1126/science.308.5726.1233a

The cool greens and blues on this map are good news for Californians because they signify a low risk of earthquakes. Worried residents and curious visitors can now check the local quake forecast throughout the state, thanks to a new online map that's updated hourly. The site won't tell people when a big quake is imminent, but it can predict the probability of aftershocks, which can still cause substantial damage.

The map is the brainchild of seismologist Matt Gerstenberger of the U.S. Geological Survey in Pasadena, California, and colleagues. Their procedure, published in last week's issue of Nature, uses all the known faults in the state and records of past earthquakes to generate a baseline historical level of risk. Whenever an earthquake occurs, the program estimates the likely locations and sizes of aftershocks and maps them. Blue signifies a one-in-a-million chance of intensity 6 shaking (forceful enough to break windows and crack plaster), whereas red indicates a greater than one in 10 chance.

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