Two tremors struck about 25 miles from the town of Concepcion, the first registered at 6.0-magnitude. Later, a 6.6-magnitude quake sent residents scrambling for cover.

There were no immediate reports of damage or casualties from the aftershocks.

The president of Chile says she's confident her country will bounce back from the devastation of Saturday's 8.8-magnitude earthquake. But President Michelle Bachelet is estimating it will take three years to rebuild the hardest hit regions. "It's going to be very hard moving ahead," the president told ADN radio.

The Associated Press reports that the quake and the tsunami it triggered killed more than 800 people, and devastated communities along more than 300 miles of Chile's Pacific coast.

This morning there have been powerful aftershocks that sent residents running from their homes. The original earthquake occurred along the tectonic boundary where the Nazca Plate, moving eastward, is forcing its way under the continental plate of South America, Susan Potter, a geophysicist with the U.S. Geological Survey's National Earthquake Information Center, told The AP.