This Is the Biggest Earthquake to Ever Shake Florida

Florida is not known for its seismic activity, but on January 28, 1946, the Sunshine State experienced its largest recorded earthquake in history. The magnitude 5.9 quake struck near the town of St. Augustine, about 200 miles north of Miami, and was felt as far away as Georgia and Alabama. The quake caused minor damage to buildings and roads, but no injuries or deaths were reported.

What Caused the Quake?

The origin of the 1946 Florida earthquake is still a mystery, as the state lies far from any major tectonic plate boundaries or active faults. Some scientists have suggested that the quake was related to a deep-seated fracture zone in the crust, or that it was triggered by changes in the pressure of groundwater or oil extraction. Others have proposed that the quake was caused by a meteor impact, a submarine landslide, or a nuclear test. However, none of these hypotheses have been conclusively proven.

How Common Are Earthquakes in Florida?

Earthquakes are rare in Florida, but not unheard of. According to the U.S. Geological Survey, there have been about a dozen earthquakes of magnitude 3.0 or higher in the state since 1727, most of them occurring in the northern part of the state. The most recent one was a magnitude 3.7 quake that occurred near the Alabama border in 2016. The USGS estimates that the probability of a damaging earthquake in Florida is less than 1% in any given year.

How Prepared Is Florida for a Future Quake?

Despite its low seismic risk, Florida is not immune to the effects of a large earthquake elsewhere. For example, in 1886, a magnitude 7.3 quake that struck near Charleston, South Carolina, caused widespread damage and was felt throughout Florida. In 2010, a magnitude 7.0 quake that devastated Haiti was also felt in parts of Florida, especially in high-rise buildings. Therefore, it is important for Floridians to be aware of the potential hazards of earthquakes and to take some basic precautions, such as securing furniture and appliances, having an emergency kit and plan, and knowing how to drop, cover, and hold on during a quake.


The 1946 Florida earthquake was the biggest one to ever shake the state, but it remains a geological enigma. Earthquakes are rare in Florida, but they can still pose a threat to the state’s safety and infrastructure. Floridians should be prepared for the possibility of a future quake, either in their own state or in a neighboring region.

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