According to USGS, Alabama was rattled by two earthquakes practically in the same location last night, north and west of Birmingham. The first earthquake struck near Addison at 9:17 pm from a depth of 16.2 km; it was rated a magnitude 2.4 event. The second earthquake struck about 40 minutes later at 9:59 pm about 4,000 feet north and east of the first from a depth of 14.8 km; it was rated a slightly weaker magnitude 2.3 event. No damage or injuries were reported from either quake.
Earthquakes with a magnitude of 2.0 or less are rarely felt or heard by people, according to USGS, but once they exceed 2.0 more and more people can feel them. While damage is possible with magnitude 3.0 events or greater, significant damage and casualties usually don’t occur until the magnitude of a seismic event rises to a 5.5 or greater rated event.
According to the Geological Survey of Alabama (GSA), earthquakes aren’t completely rare in the state. According to GSA, “Most of the earthquakes we experience in Alabama are associated with the Southern Appalachian Seismic Zone (an extension of the East Tennessee Seismic Zone) that runs along the Appalachian Mountains from the northeastern corner into the central part of the state and the Bahamas Fracture Seismic Zone in southern Alabama.
The strongest earthquake to ever hit the state was a magnitude 5.1 event in 1916 in northern Shelby County…