An earthquake of preliminary magnitude 5.7 shook Ecuador's coast Thursday, causing one death when a teenager was electrocuted by a fallen power line, authorities said.

The U.S. Geological Survey said the struck at a depth of about 80 kilometers (49 miles) and was centered nearly 20 kilometers (12 miles) northeast of the port of Guayaquil.

The Geophysical Institute of Ecuador said the tremor was felt over most of country, though "weakly" in the mountains.

Jorge Vera, mayor of the Simón Bolívar canton in the coastal Guayas province, said a 16-year-old was killed. He said a high voltage cable fell while the victim was engaged in "a sports activity," but gave no further details.