Walnut Creek estimates increased 10 to 25 percent, according to Allison M. The geologic basins are caused when tectonic plates push and strain the earth, warping the rock, said Petersen.įor San Jose, estimates of ground motion have climbed 5 to 10 percent. “Before there were just estimates” of the long slow waves that flow through the region’s sedimentary basins, said Mark Petersen, a research geophysicist with the USGS in Golden, CO. The maps and supporting documentation also are used by municipal planners to create building codes. The maps are not meant to alarm current or future residents of those areas but to help them prepare and reinforce their homes before the next earthquake hits. Long bridges and tall buildings are particularly susceptible to the longer wavelength of ground shaking seen in sedimentary basins, the kind of soils that underlie San Jose and Walnut Creek, according to the new assessment, announced at the annual meeting of the American Geophysical Union in San Francisco.
#Walnut california earth quake update
Geological Survey released new earthquake hazard maps for the nation on Thursday, boosting the risk of seismic damage in the South and East Bay - especially for tall buildings.Ī more thorough analysis of the soils under the San Jose and Walnut Creek areas prompted the USGS to increase shaking estimates by 10 to 25 percent since the USGS’s last update five years ago.
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