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Fault System Enables Larger Quakes In California

Posted by samzenpus on from the teaming-up dept.

Taco Cowboy writes Researchers have mapped the land at the southern end of the Hayward Fault and found that the creep continued 15 km beyond to merge with the Calaveras Fault, which was thought to be independent. "The maximum earthquake on a fault is proportional to its length, so by having the two directly connected, we can have a rupture propagating across from one to the other, making a larger quake," said lead researcher Estelle Chaussard, a postdoctoral fellow in the Berkeley Seismological Laboratory. "People have been looking for evidence of this for a long time, but only now do we have the data to prove it". The 70-kilometer-long Hayward Fault is already known as one of the most dangerous in the country because it runs through large population areas from its northern limit on San Pablo Bay at Richmond to its southern end south of Fremont. Last month the U.S. Geological Survey estimated a 14.3 percent likelihood of a magnitude 6.7 or greater earthquake on the Hayward Fault in the next 30 years, and a 7.4 percent chance on the Calaveras Fault, but there is one problem — the estimate was based on the assumption that the two faults are independent systems, and that the maximum quake on the Hayward Fault would be between magnitudes 6.9 and 7.0. Given that the Hayward and Calaveras faults are connected, the energy released in a simultaneous rupture could be 2.5 times greater, or a magnitude 7.3 quake.

40 of 63 comments (clear)

  1. Drought solution by Dan+East · · Score: 2

    One step closer to significantly reducing California's water consumption.

    --
    Better known as 318230.
    1. Re:Drought solution by Tablizer · · Score: 1

      On a serious note, quakes do scare away population. Many of the people who come here for sunshine and acting roles suddenly freak out and move back to Peoria or whatnot after getting rattled around. If you've never been in a medium-sized quake, there's a fairly good chance you'll be traumatized by one.

      First we throw high rents and traffic at you. If that doesn't work, we get Mother Earth to toss you around. If that doesn't work, we jail you for taking long showers. And if all else fails, we give you skin cancer for baking too long in the sun. Get a hint already. -CA

      --
      Table-ized A.I.
    2. Re:Drought solution by hawguy · · Score: 2

      Please, for your own safety, do not come to California. The Bike One is right around the corner, as it has been for as long as anyone living can remember, so, if you move here, you will falll into the oceania, and die. (And wee don't need any more people driving our land prices up.)

      That doesn't change the fact that the big one *is* right around the corner, it will come, lives will be lost, hundreds of billions of dollars in direct costs may be incurred, and taxpayers will be paying much of those costs in disaster aid since many homeowners are uninsured, and even for those that are, the funds backing their insurance may run out in a large quake.

      Though I guess building a large metropolis on top of known earthquake faults is no worse than using flood disaster funds to build right back in the flood plain.

    3. Re:Drought solution by ShanghaiBill · · Score: 2

      For the people who are in California, I assume getting earthquake insurance, if financially feasible, would be best, right?

      If you live in a single family wood frame house, as most people in the East Bay do, then an earthquake on the Hayward/Calaveras Fault is not that big of a threat. The oscillations from a quake are a threat to big buildings, and bridges, but the resonance doesn't affect small structures as much. Most houses in the area are built with Hardy Frames, or some other seismic reinforcement. The biggest threat is not the quake itself, but fire, caused by broken gas lines, and hard to extinguish if the water lines are also broken. So stockpile some water jugs, clear dead trees and debris, and replace your wood shank roof with shingles or tile. Wood shank roofs were banned in new construction after the 1991 Oakland Firestorm, but some older houses in the area still have them.

    4. Re:Drought solution by Gliscameria · · Score: 1

      Could you get insurance that would cover wage loss in an event like that? Having a standing house may not mean so much if the infrastructure and economy are crippled.

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      X
    5. Re:Drought solution by schnell · · Score: 1

      The oscillations from a quake are a threat to big buildings, and bridges, but the resonance doesn't affect small structures as much.

      My understanding - and I don't remember where I read this, I wish I did - is that it isn't actually that much of a threat to big buildings either. What I read was that skyscrapers and other tall buildings are just too big to oscillate in harmony with the quake waves in a way that compounds the stresses, and that essentially all of them have steel frames anyway that allow the buildings to "bend" rather than "break." And single-story buildings don't have much of a problem as long as they aren't built from unreinforced masonry or something that won't "give" either. Instead the real "danger zone" is for two- and three-story buildings because their height is just right to sync with the timing of the waves and amplify their effect, regardless of their construction material.

      Can anyone who has a better understanding confirm or clarify the above statements?

      --
      "95% of all Slashdot .sig quotes are incorrect or completely fabricated." -Benjamin Franklin
    6. Re:Drought solution by ShanghaiBill · · Score: 1

      Could you get insurance that would cover wage loss in an event like that?

      You can get insurance for pretty much anything. Just not cheaply. Buying insurance for something that is both unlikely, and not that big of problem even if it happens, is silly. According to TFA, an earthquake on this fault has a 14% chance of happening in the next 30 years. Even if it does happen, a ~7 quake is very unlikely to "cripple the economy". The 1989 quake was that size, and did minimal damage, except for a highway overpass that was already scheduled to be torn down. That was 25 years ago, and a lot of seismic improvements have been done since. There are at least a thousand more rational things to worry about than lost income from an earthquake.

    7. Re:Drought solution by Gliscameria · · Score: 1

      But we were talking about buying insurance for the structure. If the quake is bad enough that it broke your fancy up to date house, then there's probably some significant damage to the surrounding infrastructure.

      --
      X
  2. Only in California! by Anonymous Coward · · Score: 2, Funny

    Really, a fault system that makes your problems worse?

    C'mon California, learn to program!

    1. Re:Only in California! by Megane · · Score: 2

      But is it known to cause cancer?

      --
      #naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
    2. Re:Only in California! by Tablizer · · Score: 1

      I see buffer overflows on the CA freeways everyday.

      --
      Table-ized A.I.
  3. Yes by koan · · Score: 1

    Between fracking and the draining of all the ground water in California (drought) I wonder just how much we moved the date of the big one up.

    --
    "If any question why we died, Tell them because our fathers lied."
    1. Re:Yes by PPH · · Score: 3, Funny

      Some day soon, everything east of the San Andreas fault is going to break off and slide into the Atlantic Ocean.

      --
      Have gnu, will travel.
    2. Re:Yes by Anonymous Coward · · Score: 2, Interesting

      Don't feel bad, it doesn't make the national news much: but from over pumping ground water here in Florida we now have sink holes everywhere (http://www.wsj.com/articles/SB10001424052702304172404575169014291111050). Saltwater is creeping much faster than anyone previously thought, and our springs are already all polluted (except literally a handful out of hundreds), and as if being polluted isn't enough, they are all *going dry* or have already dried up (http://www.tampabay.com/news/environment/water/floridas-vanishing-springs/1262988). Oh, and because we have no elevation anywhere and lax environmental laws on ag, ALL of our surface water is considered contaminated. Hiking in true wilderness here (what's left of it), is nearly as difficult as it is in SoCal desert with its near zero surface water. But, the voters here can't remember any more than what the last TV ad spot told them.

    3. Re:Yes by Megane · · Score: 1

      That's why Californians need to stay where they are and do NOT move to central states.

      --
      #naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
  4. Pffff... Magnitude 7? by Anonymous Coward · · Score: 2, Interesting

    Here by law anything you build has to withstand a 8.0 without structural damage. We don't even count the ones below 7.

    Regards from Chile.

    1. Re:Pffff... Magnitude 7? by kit_triforce · · Score: 5, Informative

      Laws requiring all structures to withstand an 8.0? Let's move past the enforcement nightmare that would be and look at the reality of building that strong, It would cost close to million US dollars to build a single floor, single family dwelling to those specifications. You would need a foundation between 36"-48", fully steel enforced, likely 6"x12" studs throughout 16" on center and 12'x12' or larger corner posts. The roof structure would weigh 5 to 7 times what a normal roof would, and every single wood joint would have to be reinforced with 1" thick steel plate, bolted through the stud and beam centers.

      In California structural laws are designed to preserve human life, and structures are designed to survive the shaking enough to allow people to exit, but we take the Japanese mentality that natural disasters will do damage, and it's better to rebuild every few decades.

      Besides, California is a transverse zone (primarily, north of Mendocino is subduction with divergent off shore, and some divergence from the Salton Sea south) and we deal with shallow M7-M9 earthquakes, while Chile runs along a subduction zone, with deep M15+ quakes. Your quakes have much more energy dispersed over a larger area, while ours tend to be more localized and focused. We get at most 3-5 minutes of shaking, with less than a minute of intense damaging waves, while you can have 5min+ of building-toppling destruction,

    2. Re:Pffff... Magnitude 7? by Anonymous Coward · · Score: 1

      You're pulling shit out of your ass. Public schools in California have been being built to withstand earthquakes since the passage of the Field Act. Not a single person has ever been seriously injured or killed in a 'Field Act' building as a result of an earthquake. It does not cost anywhere near $1 million to build the equivalent of a single family home. Entire public schools are built for $50 million, and most of that cost is purchasing acres of urban homes and business to demolish.

    3. Re:Pffff... Magnitude 7? by PeterM+from+Berkeley · · Score: 1

      I'm not sure you're correct about the cost, can you cite a source?
      Flexibility is often more important to withstanding a quake than strength.

      https://www.engineeringforchan...

      I recall an example, using different nails for construction in the South vastly increases a house's resistance to tornados and hurricanes.

      http://en.wikipedia.org/wiki/H...

      These can increase the wind resistance of a house 2x over standard nails, and don't cost all that much more.

      --PM

    4. Re:Pffff... Magnitude 7? by Livius · · Score: 1

      In California structural laws are designed to preserve human life, and structures are designed to survive the shaking enough to allow people to exit

      Which is exactly what 'withstand' means in the context of structural engineering.

    5. Re:Pffff... Magnitude 7? by LynnwoodRooster · · Score: 2

      Interesting... That certainly wasn't the case back in the mid 2000s. At least for the shanty town on the side of the road down to Valparaiso. I loved my time living in Chile (Vina del Mar, Valparaiso, Renaca), and it's easily the best country in South America to live in, but there was certainly a lot of shoddy construction quality...

      --
      Browsing at +1 - no ACs, I ignore their posts. So refreshing!
    6. Re:Pffff... Magnitude 7? by beelsebob · · Score: 3, Interesting

      You realise that the way you (intelligently) make buildings survive large earthquakes is not to build ridiculously strong foundations (those actually make your problems worse). Instead, it's to design the building to move and sway with the earthquake. Hence why any large office building built today in the bay area is likely to be sat on big rollers, and/or have a weight system on the roof to damp the building.

    7. Re:Pffff... Magnitude 7? by Ravaldy · · Score: 1

      The company I work for manufactured heating products for projects in California. The changes we had to make to our heating equipment for it to meet the quake requirements was huge and the product ended up costing twice as much. I figure it's just part of the cost of building commercial and industrial buildings in California.

    8. Re:Pffff... Magnitude 7? by Khyber · · Score: 1

      "Laws requiring all structures to withstand an 8.0? Let's move past the enforcement nightmare that would be and look at the reality of building that strong"

      You're horribly ignorant of earthquake measures for buildings. For one, overall structure strength isn't key, it's flexibility and sheer forces handling for the building itself, and THEN ON TOP OF THAT, it sits atop sliding pads meant to keep a good deal of that energy from ever affecting the building in the first place.

      Speaking as a California resident, I've dealt with plenty of earthquakes. Outside, on your feet and on the pavement, you'll feel the fuck out of something as meager as a 4.0. Indoors, with our technology (assuming your place was built within the past 20 years) a 6.0 can roll through with the epicenter a couple kilometers away and half a kilometer down, and your pictures on the wall will only be barely off-kilter. You might have a few dishes in your cabinets moved to where the cabinet doors are slightly ajar.

      Try living in the area and building in the area before you start speaking of things you seem to know nothing about.

      --
      Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
    9. Re:Pffff... Magnitude 7? by Khyber · · Score: 1

      Actually, it's not the nails, it's the better bracing clips we have for that.

      I just finished construction on a building out in tornado alley, Texas. Much different than what I was using 20 years ago helping my father doing roofing and joist work.

      --
      Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
    10. Re:Pffff... Magnitude 7? by jbengt · · Score: 1

      What kind of "heating products" are you talking about? Because the projects I've worked on located in earthquake-prone areas used essentially the same products as elsewhere, but added more bracing, additional/independent hangers for ceiling-mounted items, constrained vibration isolators, etc.

    11. Re:Pffff... Magnitude 7? by Ravaldy · · Score: 1

      I think I know what type of products you speak off. In our case it was Radiant panels. These panels replace your ceiling tiles (some of them depending on BTU requirements). The trick was taking the existing product that's just a aluminum extrusion and adapting it so it could be fastened to the T bar. his resulted in a partial re-design of the product since new extrusions had to be developed and manufactured. The extrusion being of lower purchase volume (custom to these types of jobs) resulted in higher cost per feet of extrusion.

      Addition labor to install the panels also had to be considered since fastening the panels to the T bar wasn't standard practice. Our company also had to provide a certification which we had to pay for. That cost was obviously blended into the cost of the job.

    12. Re:Pffff... Magnitude 7? by kit_triforce · · Score: 2

      Try living in the area and building in the area before you start speaking of things you seem to know nothing about.

      Well, my home is within 10 miles of the San Andreas Fault, and my work is built entirely within the historical San Andreas fault zone (my office lies less than 1/2 mile from the current southern branch). I am a native Californian and have ridden out many earthquakes, both in and out of school.

      And to address other concerns, the Field Act is insufficient for the high end for potential quakes. It it designed to handle M7 quakes, while historical data shows that a M7.9 has occurred in California. Note that the strongest quakes since 1933 were 2 M7.3. My research in getting my BA in geology showed that up to about a M9 could theoretically be possible, and that the historical data may be underestimated (the 1812 Wrightwood-area earthquake had one report suggesting a possible M9.2).

      Also, I was generally estimating the design, but I was also referring to low one story buildings, as opposed to multiple floor structures. Larger buildings require a very different approach to their foundations (in order to reduce oscillation). The original statement said "withstand a 8.0 without structural damage" and while a M8.0 off a subduction zone is no where near as powerful as a M8.0 off a transverse zone at the surface, I seriously doubt that any country has the economics to build to such a high standard across the board.

  5. Fault(y) theory by eis2718bob · · Score: 1

    Funny thing how so many earthquakes are on a "previously undiscovered fault."

    The only things we know about earthquakes are: (1) little ones seem to happen after bigger ones, and (2) they roughly occur in the same place as previous ones.

  6. Re:dumbass sciantust's by Kobun · · Score: 1

    I know I'm getting whooshed here, but ... logarithm. http://en.wikipedia.org/wiki/R...

  7. Re:dumbass sciantust's by crimson+tsunami · · Score: 1

    clueless idiot.
    Learn what a log scale is...

  8. Quake by ls671 · · Score: 2

    Some Californian found a bug in quake that enables you to make your game environment larger?

    --
    Everything I write is lies, read between the lines.
  9. Re:dumbass sciantust's by Mr+D+from+63 · · Score: 2

    clueless idiot. Learn what a log scale is...

    Obviously its for weighing lumber.

  10. Re:dumbass sciantust's by PapaSmurphy · · Score: 1

    Well played, sir! Well played.

  11. Enables larger quakes?!???1?? by burtosis · · Score: 1

    WTH geologists why are you ruining life for these people. Your discovery ENABLED these quakes where the state was obviously disabled before you went mucking around like some caffinated and curious teenager in a mess of java. If anyone gets hurt or there is any property damage you just opened yourself up to the largest lawsuit in California history. Hope you are happy you smug bit****.

  12. Geologist... by Anonymous Coward · · Score: 1

    Oddly enough I'm Geologist / Software guy... Hey, you go where the money is. Anyhow...

    I'm amused that there are still people that fail to recognize the connection between the Hayward and the Calaveras faults. What's even more amusing is the belief that San Pablo bay is somehow it's terminus. It is not. It continues up thru Napa and can even be found north west of Willits as something called the Maacama rift, where it transitions from being a fault to being a region of profound folding & stress. All of them are related to the San Andreas, and ultimately the Mendocino triple-junction.

    How do we know this? Besides being able to line them all up on a map? Geochronology & Sedimentology. Roughly 5 million years ago, the "Bay" was elevated, and the debris flow from weathering was inland to the Pleasanton-Livermore valley, and west to the SF peninsula. Moving as a block, fretting up and down over time, implies those systems are all connected, and work in concert.

    1. Re:Geologist... by hax4bux · · Score: 1

      I also thought that comment about ending at Richmond was wrong.

      Don't forget the recent Napa quake and suggestions that the Napa River is also a fault.

  13. precedence of merging faluls in China & Japan by peter303 · · Score: 1

    The 2011 quake that clobbered the nuclear reactors in Japan was three historic faults going off at once and one of the largest quakes in recorded history- a rare M9 quake. Although there was a Tsunami seawall and nuclear shutdown systems, they had not designed for this large an earthquake.

    Ditto the 2008 China Sichuan quake- it broke several nearby faults, resulting in a unexepctedly large quake. Neither China nor Japan had seen quakes this large in these areas in over a thousand years of recorded history.

    So USGS seismologists are rightly concerned whether this could happen in the US.

  14. Re:dumbass sciantust's by Lodlaiden · · Score: 1

    I wish I had a mod point for you.

    --
    Suborbital [spaceflight] is the special olympics of spaceflight. - Rei
  15. Re:So wait.. this is an Improvement? "Enables..." by Ann+O'Nymous-Coward · · Score: 1

    When no one was looking, Lex Luthor
    shook forty quakes. He shook 40 quakes.
    That's as many as four tens.
    And that's terrible.