A 7.1-magnitude aftershock that hit Japan today is not expected to affect the Bay Area, a U.S. Geological Survey spokeswoman said.
The aftershock is on a different tectonic plate and is much deeper than the deadly 9.0-magnitude quake that preceded it on March 11, USGS spokeswoman Susan Garcia said.
The larger quake, which produced a devastating tsunami that rippled across the Pacific Ocean, was 1,000 times more powerful than Thursday's aftershock, Garcia said.
"The aftershock is a large earthquake, but compared to what they experienced on March 11 it's relatively small," she said.
Deep earthquakes are also less likely to cause strong ground shaking and damage because their impact is diminished by the time they reach the surface, Garcia said.
--Bay City News