An unusual earthquake struck the Gulf of Mexico about 175 miles southeast of New Orleans, Louisiana and about 175 miles southwest of Pensacola, Florida and about 175 miles due south of Mobile, Alabama last night; fortunately, there is no threat of tsunami from the quake to Florida, Louisiana, Alabama, or Mississippi at this time. According to USGS, the moderate magnitude 3.3 earthquake struck at a depth of 5 km at 16 minutes past midnight Eastern Time. The earthquake struck about 3 miles below the seafloor in an area far from any known fault lines or tectonic plates. No other earthquakes have been recorded in the area or hundreds of miles around it in the last 30 days.
In 2006, a significantly stronger magnitude 5.9 earthquake struck south of this area in the Gulf of Mexico. That September 10 quake, which struck at 10:56 am Eastern Time, was strong enough to be felt across portions of Florida and Georgia. In that earthquake, USGS reported that items fell from shelves along the Gulf Coast and seiches were observed in swimming pools. Like today’s event, there was no tsunami created. People as far away as in Atlanta said they felt the earthquake.
Rare and unusual earthquakes like today’s and the 2006 event are known as “intraplate” earthquake, which refers to earthquakes that occur within the interior of a tectonic plate. Most earthquakes are interplate in nature and occur at the boundaries of tectonic plates. Because structures far from plate boundaries lack seismic retrofitting and/or engineering to make them more durable for earthquakes, the damage from intraplate quakes could be more severe than those in interplate quakes.
While earthquakes have the potential to trigger tsunamis, today’s event didn’t have the power or movement associated with an seismic disturbance that could create one. Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases. According to the National Ocean Service, the speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters. While tsunamis are often referred to as tidal waves, this name is discouraged by oceanographers because tides have little to do with these giant waves.
