Eathquakes and aftershocks from the major quake last month continue to hit the battered country.

The U.S. Geological Survey says the strongest aftershock had a magnitude of 6.9 and was centered in Chile's Libertador O'Higgins region, about 145 kilometers southwest of the capital, Santiago.

It was one of the strongest aftershocks to hit the nation since an 8.8-magnitude earthquake in late February killed about 500 people.

Meantime Sebastian Pinera was sworn in as Chile's new president on Thursday.

The aftershocks were felt by dignitaries who gathered for Mr. Pinera's inauguration at the congressional building in the coastal city of Valparaiso, 130 kilometers west of Santiago. Buildings there shook and windows rattled, but the inauguration proceeded without interruption.

President Pinera, later took a helicopter tour of quake-affected areas, including the coastal town of Constitucion, which was ruined in the initial quake.

Mr. Pinera succeeds Chile's first female president, socialist Michelle Bachelet, who is barred from a second consecutive term. A Harvard-educated economist, Mr. Pinera is expected to steer the Chilean economy toward more free market policies.

The U.S. State Department congratulated Mr. Pinera on his inauguration Thursday, saying the United States looks forward to working with him to deepen the partnership with Chile.

Mr. Pinera's inauguration marks the first time a conservative has led the country since democracy was reinstated in 1990.

Ms. Bachelet leaves office with high public approval ratings, despite criticism of the government's initial response to the initial quake February 27.

On Wednesday, the head of Chile's emergency management agency resigned in the fallout over the failure to issue a clear warning about the tsunami that followed the quake.

The Chilean government has said reconstruction will cost about $30 billion and that it will take three or four years to rebuild the country.