5 things you need to know about: earthquakes
5 things you need to know about: earthquakes
By Jennifer Davies 12:04 A.M.FEB. 13, 2010
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From the catastrophe in Haiti to a series of small temblors locally to this week’s rumbler outside Chicago, there has been no shortage of earthquakes recently. With so much seismic activity, does that mean we here in California will finally experience “The Big One”? Here is how it all shakes out:
What do all these quakes mean? As tragic as the earthquake in Haiti was, it has little bearing on what will happen here in San Diego, says Thomas Rockwell, a geologist at San Diego State University. There is no global connection between fault lines. Faults in Illinois, for instance, aren’t connected to our faults — most notably the San Andreas and the San Jacinto — so their activity doesn’t presage an earthquake here. Or you could say: What happens in Chicago stays in Chicago.
So have there been more earthquakes than usual? Probably not. Every day somewhere in the world a magnitude-6 quake occurs. Southern California has thousands of earthquakes every year — and most of them aren’t felt. Remember, not all faults are created equal. Some faults, such as the San Andreas, by their very nature create more intense quakes.
Is there still no way to predict earthquakes? Not in the short term there isn’t. The only way scientists can gauge when an earthquake might occur is by looking back at the history of a particular fault to discern the average time between earthquakes.
When is the last time the San Andreas experienced a major earthquake? In Southern California, it was in 1857 when the 7.9-magnitude Fort Tejon temblor hit. For those counting at home, that’s 153 years ago. The U.S. Geological Survey says the probability that there will be a major earthquake in Southern California in the next 30 years is about 60 percent.
OK, how scared should I be? The bad news is that geologists like Rockwell compare the wait for an earthquake on the San Andreas to being in the 10th month of a nine-month pregnancy.
The good news is that San Diego County is farther away from the San Andreas fault, so we probably won’t feel the shaking as strongly as our friends to the north in Los Angeles. Also, San Diego’s topography and soil composition are likely to mitigate some of the impact.
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