Earthquakes in Florida are extremely rare, yet seismic events do occasionally occur in the Sunshine State. Florida has one of the lowest seismic hazards in the United States, tied with North Dakota for the fewest recorded earthquakes. The few tremors that happen are typically very low in magnitude and are not related to the major tectonic plate boundaries that cause large-scale destructive quakes. The state’s occasional shaking results from forces transmitted through the Earth’s crust over vast distances or specific localized stresses, establishing Florida as a seismically quiet but not entirely silent area.
The Historical Record of Florida Seismicity
Florida’s history of recorded seismic activity is sparse, with official records documenting only a few dozen events since the 18th century. The largest earthquake to have an epicenter near or within the state was likely in 1879, possibly centered in Putnam County, which was felt across large portions of the state, including St. Augustine and as far south as Tampa. Another significant event occurred in 1781 in Pensacola, where an estimated magnitude 6-7 earthquake reportedly shook ammunition racks from barracks walls.
The state has also felt the effects of powerful, distant earthquakes. The most notable example is the 1886 magnitude 6.9 Charleston, South Carolina, earthquake, which strongly jolted towns across northern Florida. More recently, a magnitude 6.0 earthquake in 2006, centered in the Gulf of Mexico, sent minor shock waves that caused swaying in taller buildings in Southwest Florida. Since 1900, Florida has experienced fewer than 30 quakes of magnitude 2.0 or greater, with only a few exceeding magnitude 4.0.
Why Florida is Geologically Stable
Florida’s remarkable stability stems from its geological position deep within the North American Tectonic Plate, far from any active plate boundaries. Unlike the West Coast, which sits on an active margin where plates grind past each other, Florida is located on a passive margin. This means the state is not subject to the high tectonic stresses associated with features like the San Andreas Fault or subduction zones.
The state’s foundation is the Florida Platform, a massive layer of sedimentary rock sitting atop ancient, stable crystalline basement rock. This basement rock has been tectonically quiet since the break-up of the supercontinent Pangaea over 200 million years ago. The lack of stress accumulation within the interior of the plate is the primary reason why Florida is considered one of the most earthquake-free zones in the world.
Localized and Induced Seismic Activity
The rare earthquakes that do originate within or immediately offshore of Florida are examples of intraplate seismicity, a phenomenon that occurs in a plate’s interior. These events are thought to be caused by the release of stress transmitted from distant plate boundaries along ancient zones of weakness in the basement rock. The stress builds up until it overcomes the strength of a pre-existing, deep fault line, causing a sudden slip and a small tremor.
Human activities can also induce minor seismic activity, a process known as induced seismicity. Activities such as deep wastewater disposal through injection wells can alter subsurface stress conditions near old faults. The increased fluid pressure essentially “lubricates” the fault, potentially triggering a shallow, low-magnitude earthquake. The Florida Panhandle, near the Alabama border, is one area where researchers have investigated a possible connection between oil and gas operations and minor quakes due to its proximity to the unstable Bahamas Fracture Seismic Zone.
Events Commonly Mistaken for Earthquakes
Many reports of shaking in Florida are attributed to non-seismic events mistaken for tremors. Sonic booms from military aircraft conducting training exercises, especially off the coast or over the Gulf of Mexico, frequently generate loud, shaking events that can feel like a shallow earthquake. These events are often reported widely but do not register as earthquakes on seismographs.
Another common cause of ground vibration is the collapse of the limestone substrate that underlies much of the state, leading to the formation of sinkholes. The sudden drop of rock and earth creates a localized vibration easily confused with a tremor. Controlled explosions from industrial quarry blasting also produce ground-shaking and booming noises that lead to reports of minor earthquakes. Distant, major earthquakes, such as those in the Caribbean, can send subtle seismic waves that are felt in tall buildings in cities like Miami.