Late Quaternary tectonic activity of the Meers Fault, southwest Oklahoma

Abstract

The Meers fault in southwestern Oklahoma is an active fault capable of producing large, damaging earthquakes. The most recent large event is late Holocene, occurring some 1,200 - 1,300 years ago, and it was preceded by one or more earlier Quaternary events. Few faults in stable continental interior (SCI) areas are known to be active, so this fault holds many implications for seismic hazards in these poorly understood regions. Paleoseismic events probably had magnitudes of at least 6 3/4 to 7 1/4. Seismic events may be relatively larger in SCI regions and magnitudes of 7 1/2 or greater may be possible. The minimum scarp length is 37 km. Displacements have both left-lateral and high-angle reverse components. Vertical separation of the surface reaches about 5 m, while lateral separation exceeds vertical by a ratio of about 3:1 to 5:1, reaching approximately 20 m. Individual events appear to have had maximum surface displacements of several meters. This fault may be part of a larger active zone. The Washita Valley and Potter County faults also have surface expressions believed to indicate recent surface faulting. No additional active surface faults have been recognized in the Mers fault area, but activity may be concealed by poor preservation or non-brittle surface deformation. Active faults are likely to be sparse and to rupture infrequently.