Calif. offers quake maps online for first time - East Valley Tribune: Nation / World

Calif. offers quake maps online for first time

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Posted: Thursday, April 29, 2010 1:26 pm | Updated: 3:44 am, Sat Oct 8, 2011.

State officials Tuesday unveiled new maps of California's earthquake faults and geologic features, marking the first time the comprehensive maps have been offered online.

The new maps update information about earthquake faults based on new research. For example, the Midland Fault crossing the Sacramento-San Joaquin Delta is now color-coded to show that it was active up until 700,000 years ago, whereas previously it was not thought to be active that recently.

The release of the maps celebrates the 150th anniversary of the California Geological Survey, which prepares the maps, said State Geologist John Parrish. The geology map has not been updated since 1977, while the fault map was last updated in 1994. Parrish expects updates more often now.

"These are the first information maps that have now been put together entirely by the digital process," he said. "So the new editions of these maps may be coming out every two, three or five years, as opposed to 30 years."

The new maps are much easier to access by the public -- and free. They offer fine detail on the location of earthquake faults and zones of soil geology, and are integrated with Google Earth so users can see relationships between, for example, fault zones and major infrastructure projects.

Parrish said the maps will be useful for teachers, consultants, urban planners, and businesses. They are the fifth generation of maps originally produced in 1891.

"These are the most comprehensive and most detailed and most accurate maps of the state of California that have been produced," he said.

The maps can be found at

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