Thursday, October 21, 2010

My Pesky Neighbor: The San Andreas Fault

Dragon's Back Pressure Ridge on the Carrizo Plain

Neighbors are such a mixed bag.  The good ones will look after your house when you’re away, offer a friendly wave as you drive by, and sometimes even bring you cookies at Christmas.  The bad ones are often noisy, messy and destructive.   So, what to make of good old Andreas who lives (hermit like, but restless) just down the block?  Some call him a Saint.  Me?  I’m not so sure.   He’s definitely old – at least 5 million years and so, understandably, a bit creaky and unpredictable.  I try to be understanding… apparently, he’s under a lot of pressure.  Still, he’s undeniably a menace, whose threats hang over the neighborhood day and night… all year round.  It’s hard to hate him though.  He’s not exclusively destructive.  His earth shaking, uplifting ways are the source of the breathtakingly beautiful mountain vistas that surround my little dome.   I’m actually a bit of a groupie when it comes to his artistic endeavors. 

I’ve lived fairly close to the San Andreas fault my whole life, but my current proximity is frankly, ludicrous.  To say that it’s at my doorstep would be to exaggerate only by a matter of yards.  To make things even more interesting, I don’t just live along any old bit of the 800 mile stretch of faultline, I live right at the Big Bend!

“This "Big Bend" area is possibly the most significant tectonic area in California today. Here, the San Andreas intersects the left-lateral Garlock fault, the only major east-west trending fault in southern California. Earthquakes are common in this area. The Fort Tejon earthquake in 1857 (was a) magnitude 8-plus."

The schematic block model above gives a good picture of the action of the Pacific and North American plates in this area.  They are literally "squeezing together" here in a pinching sort of way that creates enormous pressure.  

Now, I'm no stranger to earthquakes.  At 4 years old, I was unceremoniously dumped out of my little bed by the 1971 Sylmar earthquake.  We were evacuated after that one because the Van Norman dam threatened to burst.  I was nearly at ground zero for the Northridge earthquake, which woke me with such alarming noise at 4am one morning, that I quite literally believed the world was ending.  The tale of what ensued the rest of that morning will have to be fodder for another post, but suffice it to say that little temblor rearranged my life in rather significant ways.

But what can you do?  I figure I have a beautiful area to live in and predicting earthquakes is a dicey business at best.  I prefer to live my life with the knowledge that my little neighborhood is several decades overdue for a catastrophic quake, lurking somewhere towards the back of my mind.  Awareness is good though, if for preparation purposes only.  So, today as my state does it's own preparation drills as part of the Great California Shake Out, I will go about checking flashlights and batteries, canned goods and water supplies and all the other little necessities of life with no power or outside  access:  a good list is here.  But I can't quite bring myself to live in fear and trembling.  I've had good neighbors and bad every single place I've ever lived.  The benefits of this mountain life far outweigh the risks and I'm content to keep a wary eye on my Saint down the street.


  1. Apparently, my little neighbor is stirring (to the tune of a 6.9 earthquake in Baja CA just now) -- hope I didn't offend:

  2. Just had a small earthquake here. USGS is reporting 3.7 near Taft (it's a little after 7am on 10/25/10)

  3. Ya, I am a bit concerned that his buddy in Japan may have stirred him :/ let's hope he just turns back over and goes back to bed ......

  4. Yikes Lisa - I hadn't really even thought about that effect, but you're absolutely right.