Database Search

qfaults web comp

Brief Report for Gulf-margin normal faults, Louisiana and Arkansas (Class B) No. 1022

Synopsis	A belt of mostly seaward-facing normal faults borders the northern Gulf of Mexico in westernmost Florida, southwestern Alabama, southern Mississippi, all of Louisiana and southernmost Arkansas, and eastern and southern Texas (Ewing and Lopez, 1991 #2032). For the purposes of his compilation, the Gulf Coast faults are divided in four large groups because they number in the hundreds. To reflect regional differences in the characteristics of the faults, those in Florida and Alabama are evaluated together in a single group, as are those in Mississippi, those in Louisiana and Arkansas (described here), and those in Texas. Because numerous individual faults are combined into a single group for this compilation, it is not possible to provide to provide digital information about the azimuth, length, and dip of each individual fault. The gulf-margin normal faults in Louisiana and Arkansas are assigned as Class B structures because their low seismicity and because they may be decoupled from underlying crust, making it unclear if they can generate significant seismic ruptures that could cause damaging ground motion.
County(s) and State(s)
AMS sheet(s)	Alexandria
Physiographic province(s)
Length (km)	0 km.
Average strike
Sense of movement	Normal
Dip Direction	S; N
Historic earthquake
Most recent prehistoric deformation	Quaternary (<1.6 Ma)
Slip-rate category	Less than 0.2 mm/yr
Date and Compiler(s)	1998 Russell L. Wheeler, U.S. Geological Survey Paul V. Heinrich, Louisiana Geological Survey