PRELIMINARY STRUCTURE FROM MOTION DATA FOR THE TOWNE PASS FAULT, NORTHERN DEATH VALLEY NATIONAL PARK, CALIFORNIA

The Eastern California Shear Zone north of the Garlock Fault is comprised of a network of northwest-trending dextral strike-slip faults (Death Valley, Owens Valley, Hunter Mountain) connected by an oblique-normal fault system (Black Mountain, Panamint) and a series of northeast-trending normal faults (Towne Pass, Tin Mountain, Eureka Valley, Deep Springs).

Pleistocene slip rates for these normal faults would provide long-term slip rate data for the area. However, none of these faults have been the subject of modern geochronologic dating of offset features, with dates coming primarily from geomorphic or relative-age slip estimates. Accurate topographic data for the study area is necessary for calculating fault offsets and slip rates. Structure from Motion (SfM), when combined with Multi-View Stereo (MVS), produces three-dimensional topographic surveys based on point-cloud data. SfM-MVS is similar to Terrestrial Laser Scanning (TLS), but can yield data sets of higher point density, allowing for possibly sub-centimeter scale errors in the resulting model. This allows for highly detailed, cost effective and efficient mapping of small field areas. Calculations based on scarp morphology can yield data on fault ages and surface offsets. This SfM study will also help define the topography of a bedrock scarp on the Towne Pass fault to potentially identify the expression of past surface rupturing events.

Here we present preliminary results from our SfM-MVS survey of the Towne Pass fault (TPf). The TPf forms scarps placing limestone bedrock adjacent to Quaternary alluvial fan deposits and within the fan deposits themselves, making the fault an ideal target for using multiple techniques to conduct a detailed analysis of slip rates and recurrence intervals. We conducted a SfM survey of the Towne Pass limestone scarps and offset fan deposits in April 2017. We present preliminary estimates of alluvial fan surface offsets, slip rates, and recurrence intervals for the TPf. Results from this study will aid in future work on TCN dating of offsets and calculating slip rates on these normal faults.