Earthquake hits under 900 miles south of Jacksonville

What's the chance for a tsunami on our coast

A 7.6 magnitude earthquake rattles the western Caribbean sending shockwaves from Cancun to the Caymans' and Yucatan Peninsula.
A 7.6 magnitude earthquake rattles the western Caribbean sending shockwaves from Cancun to the Caymans' and Yucatan Peninsula.

JACKSONVILLE, Fla. – The strongest earthquake on the planet since Thanksgiving rattled the seafloor prompting Tsunami warnings that fortunately weren't needed. 

The 7.6 magnitude earthquake happened about 885 miles south of Jacksonville in the western Caribbean Sea. The areas off the coast of Honduras where the shake happened is along a seismic hotspot where the North American plate is grinding next to the plate under the seafloor below the Caribbean sea.

The plates slide past each other about 3/4 of an inch each year along fractures in the crust below the seafloor. At times, stress builds causing tremors. 

The reason why a tsunami didn't develop was due to the Earth blocks moving mostly horizontally in a strike-slip movement. Had the thrust of block shifted vertically, the mass of rising water would generate a dangerous Tsunami.

Depending on the forcing some are deadly. A dozen major earthquakes of magnitude 7.0 or greater have occurred in the Caribbean from near Hondouras to Puerto Rico, the U.S. Virgin Islands and the island of Hispaniola, in the past 500 years.

The most recent major earthquake, a magnitude 8.1 in 1946, resulted in a tsunami that killed a reported 1,600 people.

Tsunamis tend to be less of a concern for the Atlantic and Caribbean compared to a the active ring of fire areas in the Pacific but, Ten Brink, a geologist who studies earthquakes, tsunamis and geology, says there are many causes for Caribbean threats.

"The threat of major earthquakes in the Caribbean, and the possibility of a resulting tsunami, are real even though the risks are small in the bigger picture," Brink said. "Landslides and volcanic eruptions can also cause major earthquakes and potential tsunamis in this region. It has happened before, and it will happen again." 

The tsunami threat to the east coast of Florida does exist but the odds are much lower. A Tsunami from underwater landslides is more possible rather than a direct wave of water rushing from an epicenter. 

The University of Miami studied an undersea pile of mud west ot the Bahamas that could slide down the Great Bahama Bank setting a tsunami toward Florida's east coast. Any Cuban earthquake over a magnitude 5.5 on the Richter scale could trigger a slide.

If the landslide took place at the Little Bahama Bank, the at-risk area would extend up to the  southern St. Lucie County. 

But even in the worst-case situation any water fluctuation in north Florida might barely be noticeable.

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