Seismic Information

About Seismic

PG&E remains focused on ensuring that Diablo Canyon continues, and improves upon, its strong record of safe operations. This includes making the facility resilient to natural hazards, including earthquakes and tsunamis.

PG&E is the only utility in the country that employs a seismic department staffed with experts. The scientific staff continually studies earthquake faults in the region of the power plant and global seismic events as part of the plant's comprehensive safety program.

In November 2008, the U.S. Geological Survey (USGS), working in partnership with PG&E's geosciences department, discovered a new shoreline fault zone, and PG&E evaluated whether that new feature presented a safety risk to the plant. PG&E submitted its evaluation to the Nuclear Regulatory Commission (NRC) under the commitment of its current operating licenses. PG&E's evaluation confirmed the plant has adequate safety margin to withstand maximum ground motions postulated to occur from faults in the region, including the shoreline fault.

PG&E plans to undertake high-energy offshore 3-D studies of the shoreline fault's deeper regions as soon as it obtains necessary permits from various regulatory agencies, including the State Lands Commission, California Coastal Commission and County of San Luis Obispo. To address public concern regarding the seismicity of the area surrounding Diablo Canyon, PG&E is seeking to expedite this permitting process so it can begin this phase of studies as soon as possible. PG&E is also conducting significant seismic research along the Los Osos Valley and in the Irish Hills. The company will share the results with local jurisdictions to enhance their knowledge of the seismic characteristics of the region for their emergency planning and building standards requirements.

Even after we have completed these advanced studies, our geoscientists will continue their ongoing seismic research to give us, our regulators and the public confidence that the plant remains safe.