HolyCoast: Sitting on a Powder Keg

Thursday, April 26, 2012

Sitting on a Powder Keg

We had what on the Richter Scale would be a small earthquake on Monday, but the effect where I live was a sudden loud jolt followed by several seconds of shaking.  My first reaction was that something had exploded nearby.  I knew the Newport-Inglewood fault that runs down the coast has a lot of potential for a devastating quake, but never knew the fault that gave us Monday's jolt has equal potential and is a lot closer:
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.
If a 7.0 let go on that fault I'm not sure much of South and Central Orange County would survive. I was surprised at the violence of Monday's small quake - a 7.0 would be a ride I definitely don't want to take.

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