Earthquakes have rocked the powerful San Andreas fault that splits California far more often than previously thought, according to UC Irvine and Arizona State University researchers who have charted temblors there stretching back 700 years.
The findings, to be published in the Sept. 1 issue of Geology, conclude that large ruptures have occurred on the Carrizo Plain portion of the fault – about 100 miles northwest of Los Angeles – as often as every 45 to 144 years. But the last big quake was in 1857, more than 150 years ago.
You can see the fault running thru the Carrizo Plain in a USGS map. It is toward the southern end of the San Joaquin valley. That seems a much bigger problem for Bakersfield than for California coastal cities.
UCI researchers said that while it’s possible the fault is experiencing a natural lull, they think it’s more likely a major quake could happen soon.
“If you’re waiting for somebody to tell you when we’re close to the next San Andreas earthquake, just look at the data,” said UCI seismologist Lisa Grant Ludwig, principal investigator on the study.
If an 8.0 earthquake lets loose then anyone have a good idea on the size of the impact 75-100 miles away given California geology? Big quakes like the New Madrid 1812 that occur in less rocky soil can propagate much further. That one rung church bells in Boston. But the US West Coast doesn't have the geology needed for major damage over hundreds of miles. Still, what's the realistic diameter of the major damage area?
|Share |||Randall Parker, 2010 August 22 02:17 PM Dangers Natural Geological|