A new study released by the University of Hawaii Manoa reveals “large-scale” motion around the San Andreas Fault in California. The fault runs most of the length of California, and is responsible for a series of destructive earthquakes throughout history—most famously the 1906 earthquake in San Francisco that damaged over 80 percent of the city.
According to the study, 125 mile-wide “lobes” of rising and sinking land have been identified with GPS mapping. Scientists have previously measured the horizontal motion of the fault, but this is the first time they’ve been able to accurately map the fault’s vertical motion. This motion, which amounts to only a few millimeters a year, is the result of the two plates—the North American and Pacific plates—straining against each other as they move in opposite directions. The buildup of tension this causes will eventually result in an earthquake, although the size and scale of it remains very difficult for experts to predict.
The GPS mapping is a win for scientists, but is ultimately bad news for California. According to their study, the southern portion of the San Andreas Fault ruptures roughly every 150 years. A National Geographicarticle points out that the last major earthquake in that region was a magnitude 7.9 that hit near Los Angeles in 1857, roughly 150 years ago. Other areas have gone even longer without a quake. This doesn’t necessarily mean another earthquake is imminent, as the study points out that the actual fault ruptures can vary by a century or more. It does, however, mean that pressure is continuing to build along the fault, in some parts for over 300 years.
Many have speculated about what would happen if an area—which is far more densely populated today than 100-150 years ago—were to be hit by another major earthquake. Most signs point to widespread destruction, especially if it were to hit near one of the state’s major cities. Hopefully, things will stay put for as long as possible.
source: complex.com BY CHRIS MENCH