Mysterious 'experimental explosion' detected off Florida coast sparks earthquake alertDialy Mail ^ | 7/28/2026 | Stacy LiberatorePosted on by sopoAn '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. This is the second 3.9 magnitude "experimental explosion" earthquake off northeast Florida in the last two weeks. The USGS records experimental explosions because its network of highly sensitive seismographs detects the ground vibrations they produce. Such events are typically linked to controlled military exercises, including underwater ship shock trials, as well as scientific seismic research and industrial mining operations.