Rural So Cal epicenter of big California quakes

The two earthquakes that struck on 4 and 5 July, with Richter scale readings of 6.4 and 7.1 respectively, were centered in California's high desert, closest to the Kern County city of Ridgecrest, population  27,616.  The small city lies nearly at the point where San Bernardino County and Inyo County meet Kern County; another nearby population cluster is called Inyokern.  This is a sparsely populated area several hours east/northeast of Los Angeles, in the Mojave desert.

That the epicenter of the quakes occurred in such a sparsely populated area would seem to explain why the quakes caused relatively little damage, as this LA Times story speculated a few weeks ago.  The headline for Rong-Gong Lin II's story is "Ridgecrest earthquake mystery:  Why so little destruction from such huge tremblors?" Here's a key quote about the relative lack of damage and the reasons for it: 

Yes, mobile homes were torn off foundations, chimneys fell, gas lines leaked and some homes caught fire. But overall, most buildings did fine — and many businesses were up and running within a day or two of the biggest shock, a magnitude 7.1. 

“Ridgecrest, I’m just amazed,” California Earthquake Authority structural engineer Janiele Maffei said of the light damage.

As a result, Ridgecrest suffered far less damage than cities hit by less powerful quakes in recent years, including Napa and Paso Robles, where older buildings in the downtown areas crumbled amid the shaking.

Ken O'Dell, president of the Structural Engineers Assn. of Southern California, commented: 

You take a 7.1 and put it into the Hollywood fault or Newport-Inglewood fault in Long Beach — we’re going to see substantially different levels of damage.  Ridgecrest did a very good job surviving this particular 7.1.

But Keith Porter, a research professor at the University of Colorado Boulder, said Ridgecrest’s result should not be seen as a “victory lap.”

We still have dangerous buildings, and we still have a building code that is not optimal and doesn’t protect society as well as it could.  Instead of a dozen collapsed manufactured homes, hundreds or thousands of collapsed manufactured homes. Instead of four or so building fires, hundreds of building fires.

Porter thus suggests that the relatively small population and limited built environment of Ridgecrest accounts in large part for the minimal damage.

Lin also compares the relative lack of damage from the Ridgecrest quake to the likely damage from quakes of similar intensity in most populated regions of the State.

A U.S. Geological Survey simulation said a plausible magnitude 7.1 earthquake on the Hayward fault in the Bay Area could kill 800 people, burn the equivalent of 52,000 single-family homes and displace 400,000 people, worsening the region’s housing crisis.

And a hypothetical magnitude 7.8 earthquake that would send violent shaking waves along a 186-mile section of the southern San Andreas fault could kill 1,800 people, leave 50,000 injured and cause lasting harm to Southern California’s economy.

Finally, here's a link to some cool satellite photos showing the actual shift in the earth/plates during the earthquake.

Another interesting story about the Ridgecrest earthquake regarded the town's newspaper, the Ridgecrest Independent, and the fabulous job it did covering the quake.  Here's the lede for the CNN story:

Saturday's edition of the Ridgecrest Daily Independent newspaper was just about to go to the printing press when the earth shook again Friday night. 

The front page headline -- "The Time Ridgecrest Rocked" -- was all about the prior day's 6.4 earthquake, which was centered near Ridgecrest. 

So the staff stripped a new banner at the very top of the page and explained that the 7.1 earthquake had caused further gas leaks and fires in the area. The Friday night timing of the quake made the paper's website and Facebook accounts the best way to get updates to readers. 

The Daily Independent is a true local paper -- with standalone stories on its home page about damage to a mobile home; the fairgrounds; and the community college.