Investigation of active faulting at the Emigrant Peak fault in Nevada using shallow seismic reflection and ground penetrating radar

Abstract

The objective of this study was to assess fault displacement, off-fault deformation, and alluvial fan stratigraphy at the Emigrant Peak fault zone (EPFZ) in Fish Lake Valley, Nevada utilizing shallow seismic reflection (SSR) and ground penetrating radar (GPR) geophysical imaging methods. A three-dimensional higher frequency GPR survey provided high resolution imaging of the top 25 meters. Two-dimensional SSR and lower frequency GPR profiles imaged the subsurface at depths ranging from 20-225 m and 4-40 m respectively. Both the SSR and GPR data revealed structural geometries dominated by NW-dipping normal faulting and corresponding antithetic faults with identifiable offsets. Near the main fault strand, alluvial fan strata dip consistently to the NW while the stratigraphic architecture becomes more complex in the down-dip direction, including colluvial wedges and small graben structures. Diffuse faulting was identified tens to hundreds of meters away from the main fault, both in the footwall and hanging wall blocks.