From: Kim Noyes <kimnoyes@gmail.com>
To: californiadisasters@yahoogroups.com
Sent: Thu, March 17, 2011 9:54:48 AM
Subject: Re: [californiadisasters] California's faults are not like Japan's
None of us knows all the facts on this yet, but I will say this much: I'm rather surprised and curious as to why there was no sea wall protecting those back-up generators when the Japanese have sea walls built along other sections of their coast.
As to Diablo and global warming: that 85 foot bluff should do fine with rising sea waters.... nobody is suggesting that the seas will rise 85 feet over the next 20 years by which time the plant will have been shut down.
Due caution is a good thing and avoiding "failures of the imagination" to quote the 9/11 report is good.
However, to breathlessly suggest Diablo Canyon's 85 foot bluffs are gonna get swallowed in the next 20 years while the plant's final run plays out is not supported by the climatological and oceanographic science.
As to the plant needing to be hardened on the inside to withstand greater shaking, neither of us knows if that is true or not but I'm sure that is going to have to be looked at again and in no small measure due to the grandstanding of our two dauntless senators.
Kimmer
In the event in Japan the tsunami is the primary cause of the reactors failures that are being seen. It is noted in the following story that Diablo is cited at being 85 ft above sea level. This will change as climate change is creating higher sea levels.The Japanese plants were hit by waves at 23 feet. The earthquake(s) were not responsible for the damage that has led to the current scenario.Part of the problem in both cases is governments relying upon seismologists and geologists under contract with the respective utility companies to provide factual information. The research provided under these private contracts is commonly woven into official maps and public releases about the plants. It must be assumed because of the contractual demands of the utilities that this information is commonly weighted in the utility's favor.Hosgri has been known to generate earthquakes at 7.3, and Diablo is built to withstand a 7.5. We have the environmental groups to thank for at least this level of protection. PG&E's consultants maintained that this level of protection was unnecessary. Originally it was to be built with a safety factor at 6.8 because most construction in California is required to withstand a 6.8. Personally Diablo should be upgraded to increase its safety ratio. Two tenths on the scale appears to be far too low of a safety range.Reasonableness sometimes falls on the upper portion of statistical analysis when millions of people are at risk. Japan is a very poignant example as this event unfolds. It was argued that greater protection was just too expensive, and unwarranted...sound familiar?And to the authors of the press release from PG&E that generated the above story and the one cited by Lin, 7.3 is not a large earthquake?I see a spider spinning a web. We do not need a nominative subjective assessment of danger.Patricia
From: Lin Kerns <linkerns@gmail.com>
To: Geology2 <geology2@yahoogroups.com>; California Earthquake Forum <californiasearthquakeforum@yahoogroups.com>; CaliforniaDisasters <californiadisasters@yahoogroups.com>
Sent: Thu, March 17, 2011 8:11:03 AM
Subject: [californiadisasters] California's faults are not like Japan's
California's faults are not like Japan's
Geology offshore of and in California would make such a massive temblor unlikely, seismologists say
By David Sneed | dsneed@thetribunenews.comWhen the Japanese earthquake occurred last week, an area the size of Maryland ruptured on the fault.
To duplicate that kind of a quake in California would require a rupture along a very long length of a fault — and that geology does not exist in the faults closest to Diablo Canyon nuclear power plant, says Tom Brocher, director of the U.S. Geological Survey's Earthquake Science Center in Menlo Park.
SourceSimilarly, seismologists are not aware of any faults farther offshore that could produce a large quake or tsunami. "There are some offshore structures, but they are not the plate-boundary features that you see off of Japan or the Pacific Northwest," Brocher said Wednesday.
Seismologists are unsure whether a newly discovered fault near Diablo Canyon and a larger fault offshore are connected and could produce a potentially large earthquake if they went off in tandem.
The Japanese fault is shaped like a ramp that dips beneath the country at a shallow angle, with a large area of contact between two tectonic plates. In contrast, California's faults are thin ribbons that extend vertically into the ground, creating a fault zone about 10 miles deep.
"We just don't think there is any way we can get a magnitude-9 quake in this part of the state," Brocher said. "The faults are just not long enough."
The closest subduction fault is the Cascadia that runs down the coast of the Pacific Northwest into Northern California.
The longest fault in the state is the San Andreas, which runs about 580 miles, including through the northeast part of San Luis Obispo County.
In order for the San Andreas to generate a massive earthquake, it would have to rupture along most of its length. This is considered unlikely because a section in the middle around Parkfield regularly has many small earthquakes, and that relieves some of the pressure.
By comparison, the Hosgri Fault offshore of Diablo Canyon nuclear power plant is about 120 miles long. The newly discovered Shoreline Fault near the plant is 15 miles long.
"The Hosgri Fault is just not long enough to give you one of the mega-quakes," Brocher said. Similarly, earthquakes along faults such as those in California do not displace the huge amounts of ocean water needed to create a powerful tsunami.
"The Hosgri is a very vertical fault," Brocher said.
Seismologists have learned a lot about the faults around Diablo Canyon since the 1980s, when Diablo Canyon was built, Brocher said.
They were initially unsure of the Hosgri Fault's exact characteristics because it was newly discovered, he said.
Original estimates of the Hosgri showed a quake potential of 7.0 to 7.5 magnitude.
At a recent meeting of the U.S. Nuclear Regulatory Commission in San Luis Obispo, PG&E seismologists announced that they are reducing the quake potential to the 6 to 6.5 magnitude.
NRC officials at the meeting said they are studying the PG&E re-analysis and hope to announce whether they can verify it by the end of the year.
Brocher said his agency has not been asked to review the PG&E report submitted to the NRC. However, the USGS does update its seismic mapping on a regular basis and includes new information that has been scientifically vetted, he said.
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