Earthquakes are not uncommon in Alabama. The illustration to the left shows epicenters of historical Alabama earthquakes from 1886 to 2007 and their respective magnitudes. The majority of the earthquakes are associated with the Southern Appalachian Seismic Zone (SASZ in northern and central Alabama) and the Bahamas Fracture Seismic Zone (BFSZ in southern Alabama). The largest earthquake on record (black circle) occurred in 1916 near Birmingham.
On Tuesday morning, April 29, 2003, a 4.9 magnitude earthquake occurred in DeKalb County, Alabama, 10 miles northeast of Fort Payne, Alabama. The quake was felt in 13 states. The earthquake was deep enough to suppress significant damage in Fort Payne, the closest city, although the event did damage weaker chimneys and formed cracks in some structures. Pictures of some of the damage is on page 6.
The largest known earthquake in Alabama occurred in the SASZ, near Birmingham, in 1916. Although no seismographs existed in the state at that time, the magnitude of the earthquake (estimated from the reported shaking intensities) was calculated to be approximately 5.1, and the epicenter was located in the Irondale area.
There have been an increasing number of recorded earthquakes in southwest Alabama. One of these was a 4.9 magnitude event on October 24, 1997, in Escambia County. This was the largest quake at that time recorded by seismographs in Alabama and the largest in the Southeast in the preceeding 30 years. Historically, the southwestern part of Alabama has had minimal seismic activity, but this quake indicates activity on the BFSZ, an ancient basement fault zone that underlies the area.
Damage photos to right: 1. Area along a creek suffered large cracks. Many of these cracks are over a foot deep. 2. A large crane was parked between a house and a clump of pine trees that grew on the edge of a sand pit. The quake caused the slope beneath the crane to slump, moving the crane and trees downward into the pit.