Cascadia's Fault - Jerry Thompson [60]
He told the team from Woodward-Clyde, “This is symptomatic of an active subduction zone.” He then tried to encourage follow-up research by suggesting, “The earthquakes don’t happen more often than every four hundred years or so, but here’s the sort of evidence you could use to tie it down.” Meaning those mud cores.
David Schwartz felt himself being swayed by the data. “From my perspective even back then, it was hard to get all of the secondary deformation if things were just sliding aseismically,” he said. The folding and fracturing of rocks along the shore, the compression in Puget Sound, the tilting of mountains—how could all that deformation happen on the surface if the oceanic plate were sliding smoothly underneath?
Schwartz explained that his company had been hired to perform the FSAR—the Final Safety Analysis Report—on the Satsop power plants, which would soon be presented to the Nuclear Regulatory Commission. Their preliminary draft back in 1974 had been written in a completely different atmosphere, when “the Cascadia Subduction Zone was never a consideration.” At that time the official U.S. seismic hazard maps “did not identify it as an earthquake source,” explained Schwartz.
The science was changing quickly, however, and so was the political environment surrounding nuclear power plants. In the next draft of the FSAR, circulated internally to the consulting board at WPPSS, a new, more cautionary tone had replaced the earlier optimism. “In that document we were definitely opening the possibility that the subduction zone should be considered as a source of strong ground motion,” he told me. This was a very different view of the situation and, not surprisingly, it didn’t go over well with the WPPSS officials. They were “not delighted by this turn of events,” Schwartz remarked dryly, and things slid downhill from there.
A different firm of consulting engineers had been hired to design the reactor, and they clearly disagreed with this alarmist talk from Woodward-Clyde of potential seismic shocks—Alaska-size jumbo quakes, backed up by a handful of mostly theoretical papers with equivocal conclusions and very few hard facts—which threatened to wreck their chances of building a pair of billion-dollar atomic power stations. They insisted on a face-to-face meeting to put things back into some kind of perspective.
Woodward-Clyde, meantime, had gone ahead, drawn its own conclusions and submitted its final draft of the safety analysis to the Nuclear Regulatory Commission, suggesting that Cascadia might indeed be a problem. Thus the tone of that next meeting was fairly poisonous, according to Schwartz’s memory. Two rival groups of engineers faced off against each other with their client—representatives from the Washington Public Power Supply System—clinging to a ringside seat.
“Looking back at this, I have to appreciate the chutzpah they had in coming to our tank and trashing us in front of the client,” said Schwartz. “They simply said we were wrong in every assumption we made that the subduction zone could produce large earthquakes, that they could demonstrate that this wasn’t the case, that mention of even the possibility of seismic subduction would kill the project with the NRC.”
The implication seemed to be that some other company should take over the entire project (removing Woodward-Clyde from the equation) and “obviously this didn’t go down well with us,” Schwartz continued. “It turned into a year of hell working with those guys!” In 1982 the NRC decided to call in outside consultants to help resolve the issue. They contacted a young geophysicist named Tom Heaton at Caltech and asked him to review the earlier preliminary safety report, the one concluding that Cascadia was not likely to generate large quakes.
Heaton told me that after reading the first, more optimistic WPPSS document, he concluded that “the reasoning was weak” and decided to consult a more senior Caltech professor to help him write a response. Dr. Hiroo Kanamori had already done extensive studies of other subduction zones around the world. Kanamori