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The Diablo Canyon nuclear power plant

Underwater sonar tests that Pacific Gas and Electric Company says are needed to gauge the seismic vulnerability of its Diablo Canyon nuclear plant have enraged fishermen — and it’s unclear whether the research will be effective.

The utility is required to study a recently discovered fault line near the Central Coast plant before it can secure permits needed to operate the facility beyond 2025.

PG&E and its regulators want to know what kind of earthquake the newly discovered Shoreline Fault could cause. The fault might intercept with the Hosgri Fault, and officials want to know whether both could rupture simultaneously.

But studying underwater faults using sonar pulses emitted from up to a dozen 250-decibel air guns towed behind research vessels, as PG&E has proposed, could frighten and harm ocean wildlife, local fishermen warned.

“This is nuts, what you are planning on doing,” Morro Bay commercial fisherman Tom Hafer said during a hearing last week, the San Luis Obispo Tribune reported. “This isn’t going to prevent a quake from happening.”

During a California Energy Commission hearing in Sacramento on Tuesday, U.S. Geological Survey researcher Samuel Johnson said the mixed rock formations that surround the faults could render the study futile. 

“That’s the kind of rock that typically yields the worst imagery in seismic reflective studies,” Johnson said. “So it’s a risk. This kind of survey may provide spectacular imagery of how these faults connect or don’t connect; or it could be a lot of money paid to produce data that aren’t that useful.”

Kory Raftery, a spokesman for the power plant, said the experiments are essential for ensuring the facility's safety.

The State Lands Commission is expected to hold a hearing on the proposed experiments in December, the Tribune reported. The experiments could begin late next year and last from two to six months.