California’s earthquake hazard map is the third update

New tsunami hazard maps highlight threat facing seven California counties — even Napa County faces risk

The latest update on the risk of a major earthquake in California remains highly uncertain.

A new map released by the U.S. Geological Survey and its California counterpart offers a clearer view of the threat to the seven California counties from a major earthquake, and now shows Napa and Kings counties as well as Ventura, Santa Barbara and Santa Diego all at risk.

“The threat level remains very high statewide in California and even Napa County faces imminent risk,” the U.S. Geological Survey said.

The latest version of the earthquake hazard map is the third update. It added new earthquakes, earthquakes that occurred after the last update, which was in 2012 and the 2015 earthquake. It also added new segments, or “regions,” in Southern California.

The data collection is part of the Statewide Integrated Seismic Network (SINW), which produces earthquake hazard information at the national and regional levels.

All of the above information is compiled, reviewed and updated each year by SINW and is made available to the public online.

“For California, these are the latest data that we put together as officials evaluate the status of earthquake hazards in the state,” said Mark Young, SINW’s chief scientist. “The state’s coastal areas are at the highest risk for a major earthquake, as is every coastal county in the state, and we continue to feel the full force of the impacts that a major earthquake would have,” and to mitigate the impacts, Young said.

Here are the updated maps and how they are showing at the county level:

Sutter County

The newest addition to the map is with the 2011 Big One alert. The map shows Napa and Sonoma counties as having the highest risk. In the two years since the earthquakes that caused the 2011 Big One alert and the recent two that did not, all of the major earthquakes in the state have taken place in those two counties, the earthquake hazard map shows.

The map shows the earthquakes that occurred in the last 20 years and the magnitude of the earthquake. The earthquakes were in Napa and Sonoma counties and on a major fault, the San Andreas fault, the map says.

The map shows that seism

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