Late Quaternary tectonic activity of the Meers Fault, southwest Oklahoma

Online access for this thesis was created in part with support from the Institute of Museum and Library Services (IMLS) administered by the Nevada State Library, Archives and Public Records through the Library Services and Technology Act (LSTA). To obtain a high quality image or document please contact the DeLaMare Library at https://unr.libanswers.com/ or call: 775-784-6945.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

Tectonic displacement and far-field isostatic flexure of pluvial lake shorelines, Dixie Valley, Nevada

Abstract Shoreline features formed by the late Pleistocene pluvial Lake Dixie in Dixie Valley, central Nevada, record crustal deformation resulting from isostatic rebound of the Lake Lahontan basin, and from Holocene and historic surface faulting. Constructional beach bars on the east side of Dixie Valley show eastward tilt of 0.16 m/km, indicating that lithospheric flexure due to isostatic rebound is symmetrical with the west side of the Lahontan basin. The tilt signal is potentially complicated by post-Lake Dixie fault displacements on the west side of the valley. However, elevation changes recorded geodetically across the analogous 1983 Borah Peak, Idaho earthquake ruptures suggest that coseismic deformation is probably not significant on the east side of the valley relative to the shoreline elevation uncertainties and the overall tilt signal. A survey of faulted shorelines on the west side of the valley suggest that previous fault slip rates estimated from an earlier survey of these same shorelines are in error by nearly a factor of two. Better constrained slip rates from elsewhere along the fault indicate Holocene vertical slip rates of 0.3-0.5 mm/a, consistent with estimates of long term slip rates on the Dixie Valley fault