Patterico's Pontifications


California Earthquakes (UPDATED)

Filed under: Environment — DRJ @ 8:00 am

[Headline from DRJ]

Following up on yesterday’s earthquake near Ridgecrest, California, I found this section in an AP News’ article interesting:

Lucy Jones, a seismologist with the California Institute of Technology’s seismology lab, said the earthquake was the strongest since a 7.1 quake struck in the area on October 16, 1999. “This has been an extremely quiet abnormal time,” Jones said. “This type of earthquake is much more normal … The long term average is probably once every five or 10 years somewhere in Southern California.”

Jones said that the 6.4 quake was preceded by a magnitude 4.2 temblor about a half hour earlier. The epicenter was in the arid expanse of Searles Valley, a sparsely populated region. “This is an isolated enough location that that’s going to greatly reduce the damage,” she said.

The quake was detected by California’s new ShakeAlert system and it provided 48 seconds of warning to the seismology lab well before the shaking arrived at Caltech in the Los Angeles suburb of Pasadena but it did not trigger a public warning through an app recently made available in Los Angeles County. USGS seismologist Robert Graves said the ShakeAlert system worked properly. Graves said it calculated an intensity level for the Los Angeles area that was below the threshold for a public alert. The limits are intended to avoid false alarms.

It sounds like California has so many earthquakes that officials worry about giving too much notice and people tuning out notices.

UPDATE 7/5/2019 — Another, larger quake.


34 Responses to “California Earthquakes (UPDATED)”

  1. It doesn’t help that the press reports 4.2 quakes like they were significant.

    Kevin M (61459c)

  2. I remember the ’99 quake because it happened only two years after I moved into the state, and it was the first strong one I’d experienced. Yesterday’s seemed longer, but less violent. The ’99 quake made the water in the toilet slosh very noticeably and cracked the drywall above a door in one room.

    I was thinking a few weeks ago that I hadn’t felt a quake in a long time. They’re replacing the tile roof of my building, and there are piles of large clay roofing tiles up there on the sloping surface. It occurred to me that an earthquake might cause them to slide off, but I guess the roofers know what they’re doing because nothing happened.

    If it hadn’t been a holiday, they probably would have been working up there when things started shaking.

    Dave (1bb933)

  3. I live on the ground floor now, but was on the second floor in ’99, so that might have increased the “sway” of the building.

    Dave (1bb933)

  4. Stay safe, Dave.

    mg (8cbc69)

  5. @3. LA Rule 101: if you get a place in LA, get one on the top floor; that way you can ride the stack down.

    DCSCA (797bc0)

  6. The route through Searles Valley is actually a pretty way to get to Death Valley. Once you get through Searles Valley and up into the Panamint range…
    There are some year round springs up in the mountains, bighorn sheep, some deer. You can climb up onto the ridge above death Valley and look down into that massive heat sink from a cool mountaintop with the sound of trickling water behind you.
    There are rattle snakes too, they frequent the spring areas.

    Over all a real good look at a desert mountain range ecosystem.

    My guess is far less than 1% of deep blue coastal CA gives a kangaroo rats ass about Searles Valley, much less even knows where it is.
    Trona and Argus are hot, dusty, poor, isolated borax mining towns situated next to a dry lake.
    You can watch whirlwinds twist across through the dust of the dry lake all day if you are into that sort of thing. It’s bleak all around and looks nothing like what people think California is all about. I think it has a fierce and harsh beauty about it.
    The reason they don’t alert us about a quake in Trona is because it is so far away literally and figuratively from what the rest of CA would consider civilization.

    The response to an alarm from Searles Valley would result in 48 seconds of baffled looks… and that would be from the San Berdoo County earthquake officials

    steveg (354706)

  7. Hmmm…. and the alert level for the Mauna Loa volcano was raised. I’m pretty sure this is somehow Trump’s fault for pulling out of the Paris Accords, isn’t it?

    Jerryskids (702a61)

  8. All I know is this. I flew out to California once, in around 1990, to visit a friend. His (second) wife, a native, said, “Wouldn’t it be cool if there was an earthquake while you were here?”

    I said, “No, that would not be ‘cool.’ I do not like feeling the earth move under my feet.”

    There was an earthquake in Central Texas! I wouldn’t have felt it, as I wasn’t living in Central Texas at the time, but still it’s a bit odd that when I went to California there was an earthquake in Texas.

    Gawain's Ghost (b25cd1)

  9. There was another one just now… stronger than the first 7.1, now 6.9
    Note that no one in the LA media is wondering what is going on in the lives of the people of Searles Valley.
    “OMG! The Dodger game cameras were shaking”… “OMG my pool was sloshing”… “My twitter was blowing up from the OC to Santa Barbara”
    Not “Dear God be with the people at the epicenter”

    steveg (354706)

  10. Felt noticeably stronger – and longer – than yesterday’s.

    Dave (1bb933)

  11. This one is bigger than yesterday’s. I hope the people there are ok.

    DRJ (15874d)

  12. I updated the post.

    DRJ (15874d)

  13. I have a son in the Riverside hills, he didn’t feel either one. A friend in Orange (OC) who felt them both.

    I have a retired friend who lives in Ridgecrest, will be interesting to talk with him. As mentioned on the other thread, we live nearly 350 miles away from the epicenter, didn’t feel yesterday’s quake but did feel this evening’s.

    Colonel Haiku (2601c0)

  14. Thank goodness these (so far) haven’t occurred in a heavily populated area.

    Colonel Haiku (2601c0)

  15. They are funky things to experience. Lived in SoCal from 1956 thru 1985, so we had several over those years. The worst one was after we moved up north, the ‘89 quake near Santa Cruz. We lived 100 miles from the epicenter and the shaking on that one lasted a long time and had me on the ground outside, to avoid losing my dinner. That was wick d.

    Colonel Haiku (2601c0)

  16. I understand that sparse areas won’t have as much damage as urban areas since there are fewer buildings, etc., but there are still things there. What damage do you typically see in larger earthquakes?

    DRJ (15874d)

  17. Make that wicked… dick in the dirt, sick to my stomach. Had co-workers who lived in that area that had to rebuild their homes.

    Colonel Haiku (2601c0)

  18. One thing is gas leaks from ruptured lines, leading to fires, and indeed CNN just reported one house near the epicenter caught fire and was quickly extinguished.

    Roads and bridges are often damaged. There can be rockslides in mountainous areas. Windows break. Shelves can be knocked over, or have the stuff on them knocked off.

    Dave (1bb933)

  19. Structural and foundational damage. During that ‘89 Santa Cruz quake, a friend of my wife was staying in a high-rise hotel in San Francisco, she and her husband were in their room getting ready for dinner when it hit. The swaying of the building scared the living Hell right out of them.

    Colonel Haiku (2601c0)

  20. In this case, at least, they have an elevated level of support services already in the area from yesterday’s quake, which is good for the people there.

    Dave (1bb933)

  21. And the 880 highway collapsed in a large section, crushing people and cars, folks can probably recall that. It was helpful that a lot of people got off work early that day to be home in time for the World Series game between the Giants and the As when it hit at 5:19pm

    Colonel Haiku (2601c0)

  22. 20… true… they are ready to rock.

    Colonel Haiku (2601c0)

  23. No pun intended.

    Colonel Haiku (2601c0)

  24. Hope your all safe in California. Hope the damage is minimal for all of you.

    mg (8cbc69)

  25. Initially the seismologists said there was only a 6% chance that a larger earthquake would hit Ridgecrest soon:

    Caltech seismologists said Friday afternoon that Thursday morning’s original 6.4 quake struck along a pair of faults, one running northwest and one running northeast. There’s a 6% chance that another magnitude 6 quake or more will hit the area, though the likelihood will decrease over time, seismologist Zachary Ross said during a news conference.

    Now the updated story confirms this is unusual:

    Dr. Lucy Jones, a seismologist with the Unites States Geological Survey, said the USGS has reclassified Thursday’s earthquake as a foreshock, since Friday night’s earthquake was larger in magnitude.

    “It will be ongoing,” Jones said. “It is clearly a very energetic sequence, so there’s no reason to think we can’t have more (earthquakes).”

    Jones noted that the largest aftershocks to 7.1 earthquakes are, on average, around a magnitude six, similar to Thursday.

    “Ridgecrest is likely having a hard time,” she said. “A magnitude 7 usually has aftershocks that last for years.”

    Jones noted that she hasn’t ever heard of a situation where Southern California has seen a magnitude six, followed by a magnitude seven, followed by something even bigger – but that doesn’t mean it’s impossible.

    DRJ (15874d)

  26. The Daily Mail claims there are ” multiple injuries and fires.” Yesterday the reports said the Ridgecrest hospital had been evacuated so I hope there are a lot of emergency resources/responders available.

    DRJ (15874d)

  27. “Kern County fire officials reported ‘multiple injuries and multiple fires’ without providing details.”

    DRJ (15874d)

  28. You were right about rockslides, Dave.

    DRJ (15874d)

  29. Hopefully our southern CA contingent and families of others who do live their are safe. Haiku, back your the 1989 Loma Prieta observation, late running to 1.00am Giants – Broncos MNF game on September 10 2001 may have kept a few hundred people away from the WTC the following morning.

    urbanleftbehind (db486c)

  30. How available is earth Quake insurance, specially in remote areas?

    Narciso (fddec8)

  31. It was on CBS news, but I assume they are generally wrong?

    Narciso (fddec8)

  32. If you look carefully at the chimney that fell, you will see that it was made with unreinforced CMU (concrete block). Unreinforced masonry is a big killer. Restoring power before checking for gas leaks is another. Window glass breaking and the resulting falling daggers is another.
    Then there was the CHP motorcycle officer who drove off a broken 200 ft high overpass at the CA14 I-5 interchange.
    There are not a lot of tall buildings out there in that part of CA (none to speak of) but buildings that were built and/or designed poorly will pancake.

    I’d not want to be in a Costco, Home Depot, or similar big box store with pallets stacked 20-30 feet high above during even a 5.0… a falling rice cooker could take me out.

    Dave is right about the rocks. A stiff wind, or a landslide kicked off by a lizard will be enough to drop rocks on the road around here, so a 7.1 could get you. Some of the steep winding roads could see a car or truck jiggled off the road and over the side.

    I got knocked down while walking back years ago. The trees were shaking way worse than a 70mph wind. (the wind blows them in one direction and then they overcorrect and reset. Earthquakes shake them like the are in a cocktail shaker) One minute I was walking, the trees were going nuts and then I was sprawled out in the dirt. Once it was over, it was fun to be OK. Then I started to worry about people I knew…

    The California Earthquake Authority subsidizes insurance for everyone although the carriers are limited. I use Liberty Mutual

    steveg (354706)

  33. I should not have said the CEA subsidizes everyone. The state does incentivize the companies that cover earthquakes, and does offer insurance to everyone through different servicing carriers.
    I used to live almost directly on (within 100 meters) of the Mission Ridge Fault. I paid about $1600 annually to cover structure and contents only up to $500K with a $20,000 deductible.
    The state says it can cover losses up to $14B, but I have a $100 bill that says the State of CA would run out of money way before that and go to the Feds for it.

    If you are wondering why I lived so close to a fault, its not prone to surface fracture, its capable of a 6.5 max and besides, the entire state is covered with faults that can generate a 6.5.
    Don’t sleep next to the windows….

    steveg (354706)

  34. I finally was able to speak to my buddy in Ridgecrest this morning. He told me his mobile home suffered a little damage in last night’s quake, but no issues with the pad. At 9am this morning, he and 5 others were the only folks in his park, as the others took the strong suggestion to evacuate to heart. He’d suffered no problems in the 7/4 quake but his place was shook badly in last night’s, with anything that had been on a shelf now on the floor, his “computer room” was in a shambles and his 300+ CD collection was all over the place. The mobile home park across the road is an older one and there was much damage, with units moved off pads and a large number of them on their sides or worse.

    As we were talking, there were several aftershocks – some fairly big – that rolled through… he said that is hard to deal with, as his two small dogs want to jump on his lap with each occurrence. And they’d already had trouble with looting per the authorities who stopped by to check on his well-being.

    Colonel Haiku (2601c0)

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