Earthquakes are possible in Florida, though the state is one of the least seismically active regions in the United States. The possibility of a major quake is nearly nonexistent, but minor ground tremors have been documented both within and near the state’s borders. These events are typically low-magnitude and rarely cause significant damage.
Florida’s Geological Stability
The reason for Florida’s low seismic activity is its location far from any major tectonic plate boundary. Florida sits entirely on the North American Plate, which is a stable continental mass. The state forms a classic passive continental margin, a region characterized by a lack of active tectonic processes like subduction or transform faults.
The crust beneath Florida is old and stable, consisting of the Florida Platform—a massive, submerged plateau. This platform is built upon a very thick sequence of sedimentary rock, predominantly limestone and dolostone. This composition and position insulate the peninsula from the intense geological stresses that cause frequent earthquakes elsewhere.
Documented Seismic Events and Mechanisms
Despite the overall stability, Florida has experienced rare seismic events, most of which are felt rather than originating within the state. One of the largest quakes felt was the 1886 Charleston, South Carolina, event, which caused shaking strong enough to ring church bells in St. Augustine and affect northern Florida communities. More recently, in 2006, a magnitude 5.6 earthquake deep in the Gulf of Mexico sent tremors across central and southwest Florida, though no damage was reported.
The few events believed to have epicenters in or immediately offshore Florida have been minor, such as a magnitude 4.4 shock near St. Augustine in 1879. These intraplate earthquakes are not caused by typical plate collision but are often the result of stress transfer from distant seismic zones, which reactivates ancient, buried faults deep within the stable crust. Another mechanism for local seismic activity has been the use of experimental explosions, such as U.S. Navy testing off the Atlantic coast.
Differentiating Earthquakes from Local Shaking
Ground movement reported by residents is often caused by non-geological or hyper-local phenomena rather than tectonic earthquakes. A common source of sudden, localized shaking is the formation or collapse of sinkholes, which are frequent in Florida’s karst landscape due to the dissolution of the underlying limestone. The resulting ground disturbance can feel like a sudden, sharp tremor to those nearby.
Military and industrial activities are also frequent culprits for perceived “earthquakes” across the state. Large-scale quarry blasts, where explosives are used to break up rock, can generate ground vibrations that travel for miles and are mistaken for minor quakes. Similarly, sonic booms created by military aircraft flying at high speeds can produce a loud rumble and ground-level shaking that mimics a seismic event. These unique regional disturbances are localized, non-tectonic ground movements.