Thursday, September 29, 2022

Palos Verdes Fault: A serious issue for San Onofre; Recent history of fault research in California

The Palos Verdes Fault is a serious issue for San Onofre's nuclear waste dump. Southern California Edison (SCE) refuses to admit it, but facts indicate otherwise.

What the Peak Ground Acceleration (PGA) will be from any earthquake, based on the magnitude of the earthquake as measured by its energy release, is very difficult to calculate and there is much room for error:

From Wikipedia:
"Due to the complex conditions affecting PGA, earthquakes of similar magnitude can offer disparate results, with many moderate magnitude earthquakes generating significantly larger PGA values than larger magnitude quakes."

Also, PGA is calculated for three dimensions (up/down, and two horizontal directions, usually given as N/S and E/W, but not always). To know what PGA actually occurs during an earthquake, accelerometers for all three directions must be used, and then blended (this is known as a "vector sum") Sometimes, whichever is the largest magnitude is given as the PGA for that earthquake. For example, the 2011 Tohoku Earthquake had a maximum PGA in one direction of 2.70, but the vector sum was 2.99.

The depth of the earthquake can have a large effect on the PGA for an earthquake: For example, a 1978 Miyagi earthquake of magnitude 7.7 was 44 kilometers deep and had a PGA of 0.438g and caused 28 fatalities, while the 1999 Jiji earthquake of the same magnitude but only 8 kilometers deep had a PGA of 2.92g and caused 2,415 fatalities. The 2016 Kaikoura earthquake was a 7.8, 15 kilometers deep, and had a 3.23g PGA -- but only caused 2 fatalities. So PGA alone, or magnitude alone, or even both together with depth included, cannot actually predict the potential outcome of an earthquake.

The new values for the discovery that the Palos Verdes Fault (PVF) is a connected series of faults are quadruple the previous value, therefore, San Onofre would need to survive four times (4X) the previous estimate. Notice that SoCal Edison's web page does not provide nearly enough data to make any sort of judgement as to whether their ISFSI can survive 4X more forces that originally planned for!

Also, they do not mention that they have two completely different ISFII types at the site: Is one better than the other for surviving a 7.8 earthquake nearby? If they are equally good, why did they change to the vertical style? (Note: The answer appears to be simply that Holtec offered to build the new facility quickly, which allows SCE to save millions of dollars on spent fuel pool maintenance and instead get paid millions of dollars by the U.S. Government once the waste is in dry casks.)

Also, consider the last phrase is this chart (from Wikipedia again):

0.001 g (0.01 m/s2) – perceptible by people
0.02 g (0.2 m/s2) – people lose their balance
0.50 g (5 m/s2) – very high; well-designed buildings can survive if the duration is short.

"if the duration is short" is something PGA alone does not consider! SCE does not say "if the duration is short" anywhere, do they? Of course not! But the same PGA might completely destroy the ISFSI if the duration is NOT short! So PGA alone doesn't really prove anything.

Regarding the Palos Verdes Fault specifically, I don't think any earthquake experts are saying for certain that they are sure if it will be a thrust or a strike-slip event (or a combination of both -- see LA Times quote, below) when it occurs -- and it WILL occur: The ground movement is from around one to as much as six millimeters per year, a rather large amount (and much larger than previous estimates). And as far as I can determine from researching the PVF, it is probably going to be a very shallow event.

SCE's claim about the "low ground shaking potential" in the area is not definitive and should be completely discounted, in my opinion. Instead, the PGA for each of the two types of ISFSIs at the site should be independently analyzed and reported. I doubt that it is the same for each one.

Regarding the potential for fire, a large earthquake could certainly cause one of the scores of fully-loaded fuel trucks that probably pass nearby on I-5 to overturn and spill their entire contents, only to have it flow towards the ISFSI and ignite. Combined with even a small tsunami, there could be the combination of fire and water that SCE assures us can never happen.

One more important point: Considering that there are more than 50 known active faults in the area, how many others are liable to be four (or more) times stronger than currently estimated? Almost everything about earthquake prediction is very "hit or miss." San Onofre cannot afford to miss (other than the fact that SCE is protected almost 100% from paying for damages caused by San Onofre thanks to the Price-Anderson Act, an archaic piece of legislation that limits any reactor operator to a maximum of about $13 Billion dollars in damages, no matter the actual cost in lives and property).

SCE is hiding data, playing with numbers, and ignoring facts (as usual).

Particularly egregious in this case is SCE's blatantly false claim that the millions of people who live within 50 miles of San Onofre have nothing to worry about. Each spent fuel canister has about as much radioactivity as was released from Chernobyl, which affected much of Europe as well as, to a lesser extent, the entire northern hemisphere (and the world). A spent fuel fire can be hot enough to melt concrete, meaning a fire in one canister can spread to every other canister at the ISFSI. And putting water on such a fire -- assuming you could get close enough to it without receiving a lethal dose of radiation -- would be a big mistake!

Ace Hoffman
Carlsbad, CA

Sources used for this report:

"The PVF appears to die out to the south of Lasuen Knoll..." [so, approximately directly offshore from San Onofre, or at best just a little northwest of the SanO nuclear waste dump]

"The Northridge quake, which killed 57 people, had a devastating combined side-to-side and up-and-down motion that proved especially destructive to structures. That same combined lateral and vertical movement of faults is possible along the Palos Verdes network."

Recent history of fault research in California:

Facts about earthquakes in California:

"There are hundreds of identified faults in California; about 200 are considered potentially hazardous based on their slip rates in recent geological time (the last 10,000 years)." (1)

"To be exact, there are a total of 15,700 known faults in our state." and: "And actually one of the strongest quakes ever felt in the state occurred in the shear zone north of the recent epicenters, when a magnitude 7.8 or 7.9 temblor flattened the town of Lone Pine in 1872." (2)

The 1906 SF earthquake: "would have registered as a 7.8 on the magnitude scale." (3)

The 1994 Northridge earthquake: "The major shock lasted 10–20 seconds and registered a magnitude of 6.7" (4)

The 1989 Loma Prieta earthquake was about 6.9 magnitude and lasted about 20 seconds. "The Pacific plate moved 6.2 feet to the northwest and 4.3 feet upward over the North American plate during Loma Prieta." It was felt as far away as San Diego. (5)

Recently discovered/newly active faults in California:

September 2022: "The San Andreas Fault takes an 11 degree bend south of Stanford. That has created [the Foothill Thrust Belt fault system], which could cause a 6.9 quake every 250-300 years, new research suggests. And we don't know when it last ruptured." (6)

March, 2022: "A series of these “sleeping giant” faults was recently discovered in the Long Beach/Seal Beach region" (7)

2019: "[A] few miles southeast of Santa Cruz, California, a never-before-seen cluster of faults has been found lurking on the ocean floor." (8)

2019: "[T]he Garlock fault, which runs east to west for 185 miles from the San Andreas Fault to Death Valley, has shifted 0.8 inches since July. It marks the first documented movement of the fault in the modern historical record." (9)

2017: The Newport-Inglewood and Rose Canyon fault lines were found to be interconnected: "[A] newly identified fault line that could unleash a magnitude-7.4 earthquake" (10)

2016: Salton Trough Fault...runs parallel and close to the San Andreas Fault. (11)

2011: Near Truckee: "The newly discovered, active, 22-mile-long strike-slip fault is named Polaris"..."'We weren't expecting it at all,' said Lewis Hunter, a senior geologist for the U.S. Army Corps of Engineers Sacramento District." (12)

2008: "[T]he Shoreline Fault...passes less than a mile from the [Diablo Canyon] plant. The [newly discovered] fault has the potential of triggering a 6.5-magnitude earthquake." (13)

2006/7: "We discovered a series of prominent faults near Bombay Beach [on the eastern edge of the Salton Sea] during pilot studies..." (14)

1998: “Los Angeles is caught in a vise,”..."[An earthquake research team] discovered a large, active crack in the earth, capable of causing destructive earthquakes, under Los Angeles" (15)

Changes to faults they already knew about:

2022: "A Slow-Motion Section of the San Andreas Fault May Not Be So Harmless After All" (16)

2020: "Ominous San Andreas Fault Study: Risk of a Big Quake 5X Higher Than Previously Thought" (17)

2019: "A new study by the USGS and Harvard indicates that the [Wilmington blind‐thrust fault] has been active far more recently than we knew." (18)

2017: "An Obscure Fault in Southern California Is More Dangerous Than We Thought...the Ventura-Pitas Point Fault, [is] now thought to be capable of producing magnitude 8.0 earthquakes, and even tsunamis." (19)

2017: “A powerful quake in the mid- to upper 6s could cause liquefaction around San Diego and Mission bays and locally in Mission Valley..." (20)

2016: "San Andreas fault might be stronger than we thought, new study suggests" (21)

2016: "Latest research suggests that the San Andreas and San Jacinto faults might have ruptured together in the past" (22)

2014: "Recent studies of the magnitude 6.0 Napa quake in August suggest that the fault is longer and thus more powerful than previously thought." (23)

2010: "Earthquakes have rocked the powerful San Andreas fault that splits California far more often than previously thought, according to UC Irvine..." (24)


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Report prepared September 29, 2022 by Ace Hoffman

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