Paleoseismic observations of faults in central Nevada, USA: Slip partitioning and seismic hazards between the central Walker Lane and western Basin and Range
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Authors
McNeil, James C.
Issue Date
2024
Type
Dissertation
Language
en_US
Keywords
Earthquakes , Faults , Geomorphology , Neotectonics , Paleoseismology , Seismic hazards
Alternative Title
Abstract
The Quaternary active Ione Valley fault (IVF), Ravenswood fault (RWF), Western Toiyabe Range fault zone (WTRFZ), Southwest Reese River Valley fault (SWRRF), and Eastern Shoshone Range fault zone (ESRFZ) comprise a belt of north-northeast striking, range-bounding, dip-slip faults in the Basin and Range province in west-central Nevada. The southern extent of this belt intersects the central Walker Lane in the vicinity of the Mina Deflection. To the northwest, a parallel belt of historical earthquakes in the Central Nevada Seismic Belt (CNSB) were associated with both normal and dextral displacements indicating that part of the ~8 mm/yr of Pacific/North America relative shear is transferred to the western Basin and Range. Although historical earthquakes have not occurred southeast of or adjacent to the CNSB, tectonic geomorphic features along most ranges indicate active Quaternary deformation. This thesis presents Quaternary geologic mapping along four major ranges southeast of the CNSB based on evaluation of Google Earth satellite imagery, NAIP imagery, SRTM 1/3 arc-second imagery, aerial photography, and field reconnaissance. The distribution of old, intermediate, and young alluvial fans as well as the location and relative height of fault scarps are used to assess the pattern of late Quaternary deformation and develop seismic hazard parameters. Results indicate that the lateral extent of zones of active faulting diminish to the north and south of each range and overlap with adjacent ranges potentially constraining the length of paleo ruptures. Zones of north-east and range parallel fault splays that branch from the range front occur along the southern IVF, central WTRFZ, and central RWF. The SWRRF and WTRFZ are connected by a zone of fault splays that displace young and intermediate aged alluvial fans and form a structural linkage between adjacent ranges across Reese River Valley. These zones of northeast trending fault splays may suggest a shift in active deformation from north-northeast to north-east in the late Quaternary. Efforts at selected sites along each range include assessing slip rates based on (1) quantifying vertical separation across fault scarps and (2) dating of faulted surfaces based on optically stimulated luminescence and soil carbonate development. These data are used to constrain slip-rates for a series of fault zones in central Nevada. These results have implications for estimating maximum earthquake rupture lengths, magnitudes, and displacements and contribute towards a better understanding of seismic hazards and strain partitioning in the western Basin and Range.
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Citation
Publisher
License
CC BY