The Arizona Corporation Commission is holding a public hearing on safety of the Palo Verde Nuclear Generating Station on Tuesday afternoon in Phoenix in response to all the angst over the Japanese reactor problems. I'm on the agenda to provide background on active faulting, historical seismicity, current earthquake monitoring, and earth fissure hazards.AZGS has been involved in Palo Verde siting and safety since at least the mid-1970's. Our Field Notes story from 1976 [right, available online] describes the site characterization and excavation prior to the first unit going up in 1982.
The 7-page report refers to the 1887 Sonora earthquake as a magnitude 8 event occurring about 250 miles from the plant location, so that a similar sized event was planned for on the nearest known fault, about 72 miles away. Ironically, the 1887 Sonora quake was subsequently determined to have been in the 7 - 7.5 magnitude range, meaning the plant may have been designed for a larger event than was expected.