As disaster crews and scientists investigate the havoc wrought in Haiti, questions emerge as to whether such a vastly destructive disaster could happen at home in the United States. In fact, cities are located near dangerous earthquake zones all throughout the country, from the most infamous on the West Coast to potential time bombs in the Midwest and even on the Eastern Seaboard.
The Pacific Northwest
Stretching from northern Vancouver Island in Canada to northern California is the Cascadia subduction zone, where one giant plate of the Earth's surface is diving deep beneath another one.
"The very largest earthquakes all occur on subduction zones," said seismologist Geoffrey Abers at the Lamont-Doherty Earth Observatory of Columbia University in New York. "These are also the faults that make very large tsunamis that propagate across ocean basins to cause a lot of damage."
These "megathrust earthquakes" that threaten Seattle, Portland and Vancouver can be magnitude 9 or greater, geological records reveal. The area hasn't really seen any significant seismic activity since instruments began observations roughly a century ago, "but that's a fairly short period of time, and the system's accumulating strain," Abers said.
California
The most well-known earthquake zone in the United States is the San Andreas Fault, where the Pacific Plate and the North American Plate are sliding past each other, running along heavily populated areas of California. Still, other fractures in the earth threaten the state as well, such as the Hayward Fault that lies mainly on the east side of San Francisco Bay, and previously unknown fault that caused the 1994 Northridge quake.
"The biggest earthquakes we have any evidence for in California are magnitude 8," Abers said. In California, the faults are very well studied, and the state is very well prepared.
Geologists expect the Los Angeles area will eventually be struck by an earthquake larger than any seen in recorded history.
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