Two powerful earthquakes have struck in the Atlantic Ocean, prompting one expert to warn of a possible seismic 'chain reaction' that could affect the US. The US Geological Survey (USGS) detected a magnitude 6.9 earthquake along the Mid-Atlantic Ridge between Africa and South America at 8.23am ET. A magnitude 6.7 quake struck less than seven hours earlier at 1.44am, just 50 miles north along the same seafloor fault line where the bottom of the ocean is slowly splitting apart. However, geophysicist Stefan Burns told the Daily Mail that the double earthquake was not only historic in size, but is likely...