JACKSONVILLE, Fla. – Following Friday's 7.0 earthquake in Alaska, many are wondering how they develop and whether we could possibly experience one here in Florida.
What is an earthquake and what causes them?
An earthquake is caused by a sudden slip on a fault. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction, according to the U.S. Geological Survey.
When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel.
In California, there are two plates -- the Pacific Plate and the North American Plate. The Pacific Plate consists of most of the Pacific Ocean floor and the California Coast line. The North American Plate comprises most the North American Continent and parts of the Atlantic Ocean floor.
The primary boundary between these two plates is the San Andreas Fault. The San Andreas Fault is more than 650 miles long and extends to depths of at least 10 miles. Many other smaller faults like the Hayward (Northern California) and the San Jacinto (Southern California) branch from and join the San Andreas Fault Zone.
The Pacific Plate grinds northwestward past the North American Plate at a rate of about two inches per year. Parts of the San Andreas Fault system adapt to this movement by constant "creep" resulting in many tiny shocks and a few moderate earth tremors. In other areas where creep is NOT constant, strain can build up for hundreds of years, producing great earthquakes when it finally releases.
Can earthquakes happen in Florida?
Earthquakes are rare in Florida. The state sits on the passive margin of the North American plate, a transition from land to ocean that isn't seismically active. In contrast, the western end of the North American plate — the active margin — is slipping under the Pacific Plate, triggering the medium-to-large earthquakes that are commonly experienced in California, according to LiveScience.
Alaska registers the most earthquakes in a given year, with California placing second, until 2014 when a sudden increase in seismicity in Oklahoma pushed it well past California as the second most active in terms of magnitude (M) 3.0 and greater earthquakes. In 2014 there were 585 M3 and greater earthquakes in Oklahoma and about 200 in California. As of April 2015 Oklahoma (260 events) is still well ahead of California (29 events).
California, however, has the most damaging earthquakes, including a M 6.0 earthquake near Napa in August 2014, because of its greater population and extensive infrastructure. Most of Alaska’s large earthquakes occur in remote locations such as along the Aleutian Island chain. Florida and North Dakota have the fewest earthquakes each year.