A strong 6.0-magnitude earthquake struck Wednesday in the Atlantic Ocean near Portugal's Azores Islands, the U.S. Geological Survey (USGS) said.

The USGS said that the quake struck 277 miles (445 kilometers) south of the islands at a depth of 6 miles (10 km) at 4:41 pm (1841 GMT), but the Azores's volcanic and seismic activity institute, CIVISA said it was not felt on the archipelago--the nearest land to the epicenter.