A tsunami is a series of ocean waves generated by the rapid displacement of a large volume of water, typically triggered by underwater earthquakes, landslides, or volcanic activity. Given Florida’s extensive coastlines and high population density, assessing this risk is important. While the risk is dramatically lower than in the Pacific Ocean’s Ring of Fire, Florida is not immune to the hazard, as its history and geography reveal a susceptibility to specific, non-traditional tsunami sources.
Defining Florida’s Tsunami Risk Profile
The probability of a major, seismically-generated tsunami hitting Florida is extremely low because the state is far from major tectonic plate boundaries. The Atlantic Basin is geologically quiet, lacking the subduction zones that produce the most destructive tsunamis found along the Pacific coast. The Florida Division of Emergency Management classifies the overall tsunami hazard as low.
Florida’s Atlantic coast has experienced a few documented, minor tsunami events in its history, typically distant-source tsunamis that propagated across the ocean. For example, wave activity was observed following the 1755 Lisbon earthquake in Portugal, which generated a transoceanic tsunami felt along the North American coast. More recently, the 1918 magnitude 7.3 earthquake near Puerto Rico generated a tsunami that had minor effects propagating toward the Florida region. In total, the state’s historical record includes four minor tsunami events reported on the Atlantic side.
Primary Causes of Tsunami Threats to Florida
Submarine Landslides
The most significant tsunami threat to Florida comes from the potential for large-scale underwater landslides, rather than distant earthquakes. These mass movements of sediment, known as submarine landslides, occur on the steep slopes of the continental shelf or in deeper basins. Modeling suggests that a major landslide event, particularly off the Great Bahama Bank, could generate a localized tsunami. Such an event could produce wave heights potentially reaching 4.5 meters (nearly 15 feet) along the Florida coast.
Distant Seismic and Volcanic Events
Another mechanism is a distant seismic event, particularly those originating in the Caribbean Sea. The Puerto Rico Trench is a known area of significant seismic activity along the Atlantic-Caribbean plate boundary. A major earthquake there, like the 1918 event, could generate a wave that would impact the low-lying Florida coastline within hours. The theoretical collapse of the Cumbre Vieja volcano flank in the Canary Islands is also a possible, far-field scenario that could send a massive wave across the Atlantic.
Meteotsunamis
A more frequent, though less destructive, phenomenon is the meteotsunami, generated by atmospheric pressure disturbances. These waves are caused by fast-moving weather systems, such as squall lines, that create a pressure jump pushing down on the ocean surface. As this disturbance moves over the water, it generates a wave that can be amplified by a shallow continental shelf. For instance, a 1992 meteotsunami struck Daytona Beach with a wave estimated at 10 feet, causing injuries and property damage.
Geological Factors Amplifying Impact
Florida’s unique geological features mean that any tsunami, regardless of its size or source, would have an amplified effect upon reaching the shore. The state is surrounded by a wide, shallow continental shelf, which plays a dual role in tsunami dynamics. While the shelf’s breadth can dissipate some energy, its shallowness enables a process called shoaling. Shoaling causes the wave’s energy to become compressed as water depth decreases, significantly increasing the wave’s height. This means even a modest wave in the deep ocean can transform into a damaging surge near the coast.
The state’s extremely low average elevation further compounds the danger. Much of Florida’s coastline, especially along the Gulf of Mexico, sits only a few feet above sea level. This low topography means that even a small-to-moderate tsunami wave could penetrate deep inland, causing widespread inundation rather than just localized coastal damage. Modeling suggests that water from a localized tsunami could travel up to 3 kilometers (nearly two miles) inland.
The concentration of infrastructure and population along the coast also dramatically increases the potential for catastrophic impact. Florida has a massive coastal population and billions of dollars in real estate and infrastructure built directly on the low-lying shore. This dense urbanization means that even a rare, low-probability event would be considered a high-impact hazard due to the sheer number of people and assets exposed.