Earthquakes are unsettling, but a swarm of earthquakes can be downright scary, and some San Francisco residents are worried the Big One is near.

An earthquake of magnitude 4.1 struck near Portugal's capital Lisbon on Thursday, but did not appear to cause any injuries or significant damage, the country's Institute of Sea and Atmosphere said.

A third earthquake in less than a week struck Dorchester County early Monday morning, according to the U.S. Geological Survey ...