PROSPECTS for quake-prone San Francisco don鈥檛 get better. New data from the
US Geological Survey show that an earthquake anywhere on the San Francisco
peninsula, even 100 kilometres south of the city, will shake it far harder than
anyone predicted.
The top of Earth鈥檚 mantle under much of the peninsula slopes upward to the
north. At the American Geophysical Union meeting in San Francisco, Rufus
Catchings said this means that seismic waves from an earthquake south of the
city will bounce off the top of the mantle as they approach San Francisco, with
little loss of power.
Catchings says this will make the shaking of the city 10 times greater than
it would be otherwise. 鈥淚t will make a huge difference,鈥� he says.
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