Japan quake aftershocks could go on "for years"

An expert says people in Japan should brace for aftershocks from Friday's devastating earthquake which, she says, could go on "for years," though they'd get weaker as time goes on.

Dr. Marcia McNutt, director of the U.S. Geological Survey, told "The Early Show on Saturday Morning" co-anchor Rebecca Jarvis that the 8.9-magnitude temblor's power could provide electricity for a city the size of Los Angeles "for an entire year."

The aftershocks, she said, are "the unnerving part of it" in that it's not "just the five minutes of shaking from this earthquake, but it keeps going on and on and on, in terms of disrupting the lives of not only the citizens, but the relief workers. There's something called Omori's Law, which governs the aftershocks, that there's aftershocks on Day One. And half as many aftershocks on Day Two. And one-third as many aftershocks on Day Three. And it keeps going on for literally years afterwards, disrupting the lives."

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" ... The aftershocks themselves could bring down buildings that have already been stressed by the main shock itself. And they will hamper the efforts of the relief workers. "

How long could this last?

"It will taper off in time," McNutt responded, "but it could go on for years."

McNutt says efforts are on-going to get an earthquake warning system in place.

"Science," she pointed out, "tells us that it's very difficult to predict earthquakes. But, of course, this earthquake was preceded by foreshocks. And we are trying to install something called the Advanced National Seismic System, which can give an advanced warning of an event like this, which would allow safe shutdown of systems, electrical systems, gas systems, which can lessen the impact of an event just like this."