California Quaking
Sorry for posting this in its entirety but it came in a mail from KnowledgeNews.
Thought it might be of interest - especially for any Californians we have here.
Brace yourselves, southern Californians. The Big One may really be coming. A detailed new study of the southern segment of the San Andreas Fault suggests that your region is due for a major earthquake.
The study, published this week in the journal Nature, analyzed data from satellite images, seismic instruments, global positioning systems, and geological records. "All these data suggest that the fault is ready for the next big earthquake," says study author Yuri Fialko, "but exactly when the triggering will happen and when the earthquake will occur we cannot tell. It could be tomorrow or it could be 10 years or more from now."
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It's the Fault's Fault
The San Andreas Fault has produced its share of Big Ones in the past, including the earthquake that rocked San Francisco in 1906, killing thousands and destroying more than 80 percent of the city. But that quake happened along the northern part of the fault. A 100-mile (160-km) southern segment of the San Andreas hasn't seen a major quake in at least three centuries.
The Northridge earthquake that hit Los Angeles in 1994 occurred along a different fault, and seismologists classified it as a "moderate" earthquake, with a magnitude of 6.7. The release of 300 years' worth of tension along the southern San Andreas could produce a much bigger quake. How big? According to the study's author, an earthquake that released all that tension at once might reach magnitude 8.0. That's roughly the size of the 1906 San Francisco quake, and bigger than the 7.6-magnitude quake that struck Kashmir last year.
So is that as big as earthquakes get? Nope. The earthquake that triggered the Asian Tsunami in 2004 had a magnitude of at least 9.0. And the Great Chilean Earthquake of 1960--the biggest ever measured by modern equipment--had a magnitude of 9.5. It shook the earth with the force of more than 100 billion tons of TNT.
Effects of Earth's Biggest Earthquake
The Chilean quake's epicenter was 100 miles (160 km) off Chile's coast, about 200 feet (60 meters) below the Pacific Ocean's floor. When it hit, the altitude of several hundred miles of coastline shifted. Farms were plunged underwater. Docks and ports were raised or lowered by several feet. Landslides were widespread. And a tsunami generated by the quake smashed into the coast, with waves reportedly reaching heights of 80 feet (24 meters).
The quake laid waste to a huge part of southern Chile. Exact totals vary according to the source, but more than 2,000 people were killed, 3,000 were injured, and some 2 million were left homeless. Many villages were completely wiped out.
The quake's effects were felt all over the world--literally. According to seismologists, it made the entire planet vibrate like a bell for days, a phenomenon called "free oscillation," which occurs only with enormous earthquakes. And that quake was only the beginning. A series of at least nine big quakes hit Chile from May through December the same year. Chileans hope they never see another such string. Californians hope they never see such a Big One.
Blacknad.
