Why Monday’s 3.9 earthquake could cause big trouble for Orange County

April 24, 2012LOS ANGELESThe earthquake may have measured only a 3.9, but it still could make history in Orange County. Monday’s temblor, centered in the southern suburb of Laguna Niguel, could be the first measured on a fault discovered only 13 years ago and running along the coast from Newport Beach and Costa Mesa to San Juan Capistrano — close to the San Onofre nuclear power plant. The little-known fault — called the San Joaquin Hills thrust — is similar to the fault that triggered the deadly Northridge quake in the San Fernando Valley 18 years ago. Unlike the famous San Andreas Fault, which can be seen on the surface, the fracture in the earth’s crust that makes up the San Joaquin Hills thrust fault is entirely underground. Because there is no visible break in the earth’s crust at ground level, the fault is perhaps more dangerous because it’s unclear exactly where the boundaries are. Scientists weren’t aware of the blind thrust faults that triggered the 6.7 Northridge earthquake in 1994, or the 6.0 Whittier Narrows quake in 1987, until after the ground began shaking. Experts say Monday’s temblor should serve as a wake-up call, particularly to Orange County residents who mistakenly believe that quakes are more of an L.A. problem. Scientists believe that the San Joaquin Hills thrust fault is capable of generating a magnitude 7 quake or greater. The U.S. Geological Survey in 2003 conducted a scenario of such a quake and found it could trigger severe shaking on a large swath of southern Orange County, including Costa Mesa, Irvine, Lake Forest, Mission Viejo, Newport Beach, Laguna Beach, Dana Point and San Juan Capistrano. “If this morning’s earthquake was on this fault, this is an example of what the fault is capable of doing,” said Lisa Grant Ludwig, a UC Irvine associate professor who was the lead author of a paper in the journal Geology in 1999 announcing the discovery of the San Joaquin Hills thrust fault. “I think there’s an under-appreciation of the seismic hazard in Orange County,” Grant Ludwig said. “There is a general perception in Orange County that we don’t have as much earthquake hazard” — in part because the county has not suffered a major, destructive quake since 1933, when the area was sparsely populated. Scientists discovered the San Joaquin Hills thrust fault after noticing evidence of ancient sea life in the hills. The researchers hypothesized that the land was once below sea level, but over hundreds of thousands of years the fault caused the earth to move upward, creating the hilly terrain. –LA Times
This entry was posted in Civilizations unraveling, Dark Ages, Earth Changes, Earth Watch, Earthquake Omens?, High-risk potential hazard zone, Lithosphere collapse & fisssure, Potential Earthchange hotspot, Seismic tremors, Signs of Magnetic Field weakening. Bookmark the permalink.

17 Responses to Why Monday’s 3.9 earthquake could cause big trouble for Orange County

  1. Patrick says:

    I was at home, sitting at the computer yesterday morning in Huntington Beach, when I felt a sharp jolt. First quake I think I’ve felt since Easter two years ago. It’s kind of ironic, since I’ve been following the stories here for a few months now. I certainly didn’t expect to be reading about it on here today! Thanks Alvin. You might be interested in this story. Edison: San Onofre could restart in ‘next few months’ http://sciencedude.ocregister.com/2012/04/23/edison-san-onofre-could-restart-in-next-few-months/170761/


  2. Steve says:

    Is this, or could this, be some kind of breaking point for the ‘big one’ ?


  3. Gen says:

    The 5.5 Tonga quake at 15:15 UTC up on Thailand Seismology Bureau. Not on USGS yet.


  4. Patrick says:

    Great question Alvin! Hey, at least it was built to withstand a 7.0 mag. earthquake, and I believe a 30 foot wave. There have been several protest about this plant remaining open, I expect this only gives the protestors more reason for their concern, as if Japan’s 9.0 quake and Tsunami wasn’t enough. I believe that produced a 33 foot wave. We still don’t know the impact of the Nuclear Power Plant disaster in Japan, yet radiation is showing up along our shores, not to mention the affects on sea life. Who needs worm wood?


  5. missmarla says:

    With the increase in earthquakes, and predictions of more to come, Fresno, CA continues plans of building a nuclear plant. To accompany their 50+ yr water scam and high-speed rail project. Farmers eliminated. Cities rebuilt on top of a secretly-replaced water system. Big plans for major development / gambling communities are underway.

    Concern for human life does not exist. Former Mayor Alan Autry (aka: Bubba Skinner / CA water spokesman) is behind the cover-up of horrific crimes against property owners in order to clear the path for this project. After the annihilations, takeover of properties – reports /evidence prohibited. Records altered, perjury to deny – beyond barbaric. Now, despite the increase in seismic activity, with talk of the “big one” expected to take place at any moment, plans for a nuclear plant continue.


  6. If I remember right, the San Onofre Nuclear plant has been shut down since the beginning of this year. Although the potential for major quakes along this built along with prospects of Tsunami is a major concern in itself, it is at least one heartening fact that Orange County won’t have a Fukushima like threat.


    • AWM says:

      If I remember correctly, my brother used to live near there, the first reactor (initialy installed backwards(!), how the heck do you do that!) is still used to store spent fuel, and the second shut down due to some problems in it’s design.
      And I think it was built on the coast to use sea water for cooling!
      Like many sites, this is a problem just waiting to happen, I hope someone can give us better and more recent news.

      As usual, Alvin, keep up the good work. Yours is the first site I check each and every day.


  7. tonic says:

    Is this classed as an ancient fault line? Or, has been active, but unnoticed because there was no population there in the past.


  8. John Kilby says:

    God has said that He will destroy them which destroy the earth. Rev. 11: 18


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