In the wake of the Fukushima nuclear disaster, it's imperative for California to have more definitive knowledge about the seismic hazards near the Diablo Canyon Power Plant. An additional fault in the area was only recently discovered, and more seismological information is needed about existing faults. Technology has improved tremendously since the nuclear plant began operating in 1985, and license renewal for its two reactors — a process that takes years — shouldn't go forward without this information.
But what if the research itself causes terrible environmental harm? That's what the staff of the California Coastal Commission says would happen if plant owner Pacific Gas & Electric Co. is allowed to proceed with its proposal to blast underwater air cannons every 15 seconds in Morro Bay, for about 12 days a year over four years, to produce three-dimensional images of geologic faults. PG&E; needs the commission's permission to carry out the sonic imaging, but the staff is recommending against it.
Thousands of marine mammals, with their sensitivity to underwater sounds, would be affected in unknown ways by the disturbance, a staff report says. Of special concern are Morro Bay's 2,000 harbor porpoises, a distinct population that remains in that area and doesn't interbreed with other harbor porpoises. If they were driven from the bay by the cannons, their ability to survive would be uncertain. In addition, the blasts would kill millions of fish and other forms of sea life.
Yet a nuclear accident is a far worse scenario to contemplate, for both its threat to human safety and the environmental damage it would cause — including to Morro Bay's marine life. Seismic ignorance is not an option.
PG&E;, to its credit, has done tests on one active geologic fault that has allowed it to drop a zone from the list for the sonic blasts. Still, there's more that PG&E; could do to minimize the disruption. The Coastal Commission report points out the utility has not completed additional studies that, depending on the results, might reduce or even eliminate the amount of air-cannon blasting needed to complete the job. The air cannons should go off only as a last resort.
Ultimately, it may prove necessary to undertake the seismic tests even if that will carry a cost to marine life. But when the Coastal Commission meets Wednesday, it should deny the testing application until PG&E; provides a better-researched and more refined plan.