An 'experimental explosion' has been detected off the coast of Florida, nearly two weeks after a similar event occurred. The US Geological Survey (USGS) detected a 3.9 magnitude earthquake east of Flagler Beach on Tuesday. It was listed with a depth of zero feet, indicating the seismic source was at or very near the surface, a characteristic more consistent with an explosion than a typical tectonic shake. The location is about 20 miles from where another event was recorded on July 16, east of Ponce Inlet, an area where the US Navy is known to conduct Full Ship Shock Trials...