LARGE L.A. QUAKE IMMINENT (within ten years Southern California could be in line for a serious quake along the infamous San Andreas fault, seismologists have found.
New measurements suggest that the region close to Los Angeles, the traditional earthquake location in Hollywood disaster movies, could feel the effects of a real-life tremor within the next few years.The southern part of the San Andreas seems to be building up a considerable amount of strain, the work suggests. And because no significant earthquake has ruptured this portion of the fault for at least the past 250 years, it could be primed to cause a devastating event.
"It could be tomorrow; it could be ten years from now," says Yuri Fialko, a geophysicist at the Scripps Institution of Oceanography in San Diego, California, who led the study. "But it appears unlikely to accumulate another few hundred years of strain."
The San Andreas marks a major geological boundary, where the North American plate of Earth's crust grinds alongside the massive Pacific plate. In the San Francisco area, the fault has unleashed several killer quakes, including the 1906 earthquake that left the nascent gold-rush city in smouldering ruins. But the southern San Andreas has not ruptured for centuries.
Some scientists had suggested that the San Andreas could be releasing strain slowly over time, by 'creeping' along its length, or by transferring some of the strain on to neighbouring faults. But the new study suggests that neither of these processes is occurring to a significant extent.
TAKING THE STRAIN
Fialko gathered eight years' worth of radar data from European Space Agency satellites that measure in detail how the ground moves. He also added 20 years' worth of data from global-positioning measurements on the ground.
Taken together, he says, the measurements suggest that the two plates either side of the southern San Andreas are slipping past each other at around 25 millimetres per year. Without a recent earthquake to alleviate that strain, Fialko says, the fault line itself, which has remained essentially static for centuries, has built up between 5.5 and 7 metres of 'slip deficit'.
The southern San Andreas is fully loaded for the next event. — Yuri Fialko, Scripps Institution of Oceanography
If released all at once, that could result in a
magnitude-8.0 earthquake, he says, roughly the size of the devastating 1906 quake in San Francisco. Such a powerful event might threaten even those buildings constructed to earthquake specifications.
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Eerst dacht ik binnen een paar jaar, maar een eind verderop staat "could be tomorrow, or in ten years".. Hmm... zo kan ik het ook...