PG&E to use ground vibrations to help map faults

PG&E will give two public demonstrations Wednesday of ground-vibrating equipment it plans to use as part of its earthquake fault-mapping work.

The demonstrations will take place at 3 p.m. and 6 p.m. at PG&E’s community center, 6588 Ontario Road in San Luis Obispo. Members of PG&E’s geosciences team and managers of Diablo Canyon nuclear power plant will be on hand to answer questions.

The main piece of equipment participating in the demonstration will be a Vibroseis unit, a large vehicle with a ground-vibrating machine mounted on it. When in use, the equipment creates vibrations similar to a dump truck passing by, said Kory Raftery, a PG&E spokes-man.

“This is an opportunity for the public to see the truck in action and feel the vibrations,” he said.

These surveys could be completed as early as the end of the year. They will mostly be conducted on lands owned by PG&E surrounding Diablo Canyon.

However, some work will also be done along Highways 101 and 1 around San Luis Obispo, Avila Beach, Grover Beach and Oceano, as well as South Bay Boulevard in the Morro Bay and Los Osos area, Raftery said.

By tracking how the vibrations move through the ground, seismologists can gain a two-dimensional picture of earthquake faults in the area around the nuclear power plant. The utility is also planning to conduct extensive offshore seismic mapping using loud sounds generated by air guns.

The work is required in order to extend the operating life of Diablo Canyon to 2045. A final seismic report to the Nuclear Regulatory Commission is due in August 2013.