for National Geographic News
Get ready for the Big One.
About 300 years of pent-up stress in southern California is sufficient to trigger a catastrophic earthquake on the San Andreas Fault system, according to a new study.
The San Andreas Fault marks the boundary between the North American and Pacific tectonic plates. Tectonic plates are pieces of the Earth's outer crust that jostle about like constantly moving pieces of a jigsaw puzzle.
The fault is notorious for major earthquakes, including the 1906 earthquake that reduced the San Francisco Bay Area to piles of smoldering rubble.
But the 100-mile (160-kilometer) southern section of the fault, which runs south from San Bernardino to the east of Los Angeles and San Diego, has remained eerily quiet for nearly three centuries.
(See California map.)
Now, scientists believe, the fault is ready to rumble.
"It is fully charged for the next big event," said Yuri Fialko, a geophysicist at the Scripps Institution of Oceanography in La Jolla, California.
"When the event will occur, we cannot tell," he continued.
"It could be tomorrow or 20 years from now, but it appears unlikely the fault can take another few hundred years of slow strain accumulation."
Fialko reached this conclusion after studying the fault system with radar-equipped satellites and global positioning systems (GPS).
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