Pacific Gas & Electric Co. has asked federal authorities to delay the license renewal proceedings for its Diablo Canyon nuclear power plant until more thorough seismic testing of the area around the plant can be performed.

In the wake of the earthquake and nuclear crisis in Japan, people have been calling for advanced seismic testing around California's nuclear plants.

In 2009, PG&E applied to renew the licenses for its two nuclear reactors in San Luis Obispo County, which expire in 2024 and 2025. The renewal application process can take years.

"In light of recent events at the Fukushima Daiichi Power Plant, and the considerable public concern regarding the need to assure the seismic safety at DCPP, PG&E has decided it is most prudent to have completed certain seismic studies at [Diablo Canyon] prior to issuance" of the renewed federal operating licesnses," the utility said in a statement.

Though Diablo Canyon's engineers assured public officials in the late 1960s that the area around the plant had only "insignificant faults," at least two faults have been discovered since its construction, including one in 2008 less than a mile away.

That fault, called Shoreline, is thought by geologists to be capable of producing a magnitude 6.5 quake. The other fault, called Hosgri, is rated up to 7.3.

California energy authorities and legislators have asked PG&E to perform thorough studies of the seismic risks near the plant before it seeks a 20-year renewal of the licenses for its nuclear reactors.

“I commend PG&E for taking the responsible action of delaying relicensing until critical seismic questions are answered," said state Sen. Sam Blakeslee (R-San Luis Obispo). "We respect that this is a difficult decision that demonstrates their willingness to prioritize the safety of Californians.”

-- David Sarno