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Southeastern California is known for complex fault networks that accommodate strain from Pacific-North American plate convergence. The 250-km-long, left-lateral Garlock fault is integral to this system, yet its overall kinematic role within the plate boundary and relationship with faults of the Eastern California shear zone/Walker Lane belt remain poorly understood. A key area that has not been adequately studied is a 15-km stretch of the eastern Garlock fault, at its intersections with the right-lateral Brown Mountain fault and left-lateral Owl Lake fault. This segment of the fault lies within the China Lake Naval Air Weapons Station and U.S. Fort Irwin boundaries, which have restrictions on civilian access and portions of which contain unexploded ordnance, making them unsuitable and unsafe for field investigations. The purpose of this project is to use a combination of high-resolution LiDAR topographic data, remotely sensed imagery, and published geochronology data to map and establish the ages of faulted landforms along this portion of the eastern Garlock fault. The inaccessibility of this area makes it ideal for the application of remote-sensing techniques. A range of surface analysis techniques were used to differentiate and map Quaternary units in the study area. Geomorphic surface properties were determined from physiographic roughness and surface reflectance data, established from analysis of LiDAR, radar backscatter, and visual-near and short-wave infrared multispectral and hyperspectral reflectance datasets. The ages of faulted landforms were established using two approaches: (1) fault scarp and terrace riser degradation analysis and (2) a surface property-age model that links remotely sensed surface properties to new and published ages of alluvial surfaces in the region. A final goal of the study was to determine the slip rate along this segment of the Garlock fault and other faults in the map area. To accomplish this, offset landforms, such as terrace risers and channels, were analyzed in the context of the new age determinations. The results will be compared to published slip rate estimates for the region in order to better understand the Garlock fault's role within the plate boundary and how plate boundary strain is being accommodated in such an intraplate setting.
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Constraining the slip rate of the Owl Lake Fault by using LiDAR data and fault scarp degradation models
The Owl Lake Fault is an active, 19 to 25-km-long, left-lateral strike-slip fault that divaricates NE from the Garlock Fault toward Death Valley in eastern California and transfers regional strain to the fault systems in Death Valley. As an active fault, the Owl Lake Fault is a poorly understood link between the extension of Death Valley and other active faults within Mojave Desert. In addition to the larger tectonic framework, improved understanding of the Owl Lake Fault as a seismogenic structure has direct implication for the assessment of the earthquake hazard in Eastern California. A significant limitation on the understanding of the Owl Lake Fault's role is the wide range of estimates previously reported for its slip rate. These range from 0.5 to 7.8 mm/yr, which implies the Owl Lake Fault may accommodate nearly all of the present-day slip on the Garlock Fault. The project aims to constrain the slip rate and understand kinematics of the Owl Lake Fault. For this project, I have used recent airborne LiDAR data (approximately 4.6 points/m2) to map the fault and precisely measure horizontally offset landforms along the Owl Lake Fault. Subsequent to LiDAR mapping, field work facilitated the ground-truth verification of initial mapping as well as more precise measurements of small fault offsets using kinematic GPS and low-altitude photogrammetry. The detailed, local microtopography permits assessing the smallest offsets (75-100 cm) which are interpreted as reflecting the last coseismic offset. Initial efforts at refining the slip rate use scarp degradation models to infer the ages of alluvial fans and stream terraces that are offset by faulting. The final step for this project involves estimating slip rate, magnitude, and recurrence interval. Neotectonic investigations allowed to constrain the slip rate of the Owl Lake Fault as 1.1 - 1.4 mm/yr. The Owl Lake Fault can produce earthquake with the magnitude M=7.2 with the 1030 -- 1430-yr recurrence interval. This study demonstrates that the Owl Lake Fault is part of the same hazard consideration as the central Garlock Fault in eastern California.
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- PAR ID:
- 10584429
- Publisher / Repository:
- University of Missouri
- Date Published:
- Format(s):
- Medium: X
- Institution:
- University of Missouri--Columbia
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Dissertation:
- https://doi.org/10.32469/10355/94111
