Earthquakes are common off Cuba's southern coast. But they are rare off the island's northern coast. The northern city of Havana, for example, hasn't experienced a significant earthquake in more than 200 years. Which is why Thursday's quake centered to the north of Cuba was so rare.
The epicenter of the magnitude 5 earthquake, which was also felt in Key West, Florida, was 112 miles east of Havana and about 25 miles north of the Cuban coast.
Falk Amelung, a geophysicist at the University of Miami, says that’s usually a seismic sea of tranquility. It lies in the interior of a tectonic plate, and not on the boundary -- or a major fault-line zone -- where most earthquakes occur. As a result, he calls what happened Thursday afternoon a rare intraplate earthquake.“Inter-plate earthquakes are earthquakes that happen on not well known fault zones, just anywhere between the plate", explained Amelung. "Once in a while you have some random earthquakes at places where we don’t expect.”
Amelung also points out that most often these unusual earthquakes are not as strong as quakes that take place in regular fault zones – like the Caribbean’s Enriquillo-Plantain fault line. That one was responsible for Haiti’s catastrophic quake four years ago this Sunday.
“Inter-plate earthquakes can happened essentially everywhere, but the big ones are extremely rare”, Amelung said.
Which is why Thursday’s quake fortunately didn’t tear down any buildings – even if it did turn scientist’s heads.