NAPA (KCBS) – Geologists, seismologists and geophysicists gathered at the U.S. Geological Survey in Menlo Park on Thursday, sharing some of the information they have gathered on the ground in studying last month’s Napa earthquake.

“The earthquake started down around seven miles. But the way it broke, it broke up toward the surface and northward,” said Tom Brocher, Director of the U.S. Geological Survey’s Earthquake Science Center. “So it directed and focused its energy right at Napa and Napa Valley.”

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The USGS is just one group studying the quake. Scientists from UC Berkeley, Stanford University, UC Davis, USC, and the California Geological Survey have all been in Napa Valley, combing the region. The information is seen as a key for hazard assessment.

The early studies have found the quake produced a crack six miles long at the surface, with up to 18 inches of slip on that crack.

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“We’re using imagery that has been obtained from satellites and unmanned vehicles and helicopters to help us map that cracking,” said Brocher.

The results are expected to produce much better maps of active faults in the area.

Brocher said aftershocks are expected to continue for months.

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There will be more studies to examine how rapidly the fault is moving.