Towards morphologic and cosmogenic dating of paleoearthquake and fault slip rates in the Central Nevada Seismic Belt

Tabor J. Reedy, & Steven G. Wesnousky

Published August 15, 2016, SCEC Contribution #6995, 2016 SCEC Annual Meeting Poster #104

The Pleasant Valley Fault and Dixie Valley Fault are located approximately 30km and 90km south of Winnemucca NV, within the Central Nevada Seismic Belt a region of aligned, nearly continuous, historical normal-fault earthquakes that produced surface rupture. We have commenced study at two sites. The first, in Pleasant Valley, is along a small ~1 km section of the Pearce scarp near Siard Canyon that ruptured during the 1915 Ms 7.7 earthquake and the second is at Terrace Creek in Dixie Valley that ruptured during the Ms 6.8 earthquake of 1954. At each site, aerial photos collected from a drone are processed with Agisoft PhotoScan software to produce high-resolution DEMS. Preliminary analysis of scarp profiles with a linear scarp diffusion model across the scarp near Siard Canyon suggest that the 1915 earthquake was preceded ~14.5 ky ago by an event of ~ 4 m vertical displacement. Sediment samples taken from a 2 m deep pit excavated on the hanging wall have been collected for cosmogenic dating of the upper alluvial surface and will be used as an internal consistency check on the scarp diffusion analysis and place a bound on the late Pleistocene slip rate of the Pleasant Valley scarp. At Terrace Creek the Dixie Valley fault truncates a sequence of 3 well preserved fluvial terraces and pediments which record a total of ~20 m of uplift, and 2 or more higher and older pediment surfaces, all of which record a late Pleistocene record of continued uplift. Sediments sampled from a 2-m pit on the higher of the 3 well-preserved terraces is expected to provide a bound on the late Pleistocene slip rate of the fault.

Key Words
Earthquake Geology, Neotectonics, Central Nevada Seismic Belt

Citation
Reedy, T. J., & Wesnousky, S. G. (2016, 08). Towards morphologic and cosmogenic dating of paleoearthquake and fault slip rates in the Central Nevada Seismic Belt. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology