Date of Award

5-2023

Document Type

Thesis

Degree Name

Master of Science in Earth and Environmental Sciences

Department

Geological Sciences

First Reader/Committee Chair

Sally McGill

Abstract

This study investigates the late Holocene slip history of the central Garlock Fault, using measurements of left-lateral offsets of alluvial features from airborne and hand-held LiDAR imagery, drone photogrammetry, and field measurements. IRSL dating of the offset late Holocene alluvial deposits was compared to published paleoseismic records to estimate the number of earthquakes that contributed to the offsets. Focus was given to geomorphic features offset in the past 1-4 earthquakes. Results indicate the average slip per earthquake was about 5.75 m (range: 4.75 to 6.25 m) in the past four events in the El Paso Mountains (EPM) and was 4.3-7.3 m in the past three events in Pilot Knob Valley (PKV). Left-lateral slip in the most recent earthquakes in PKV was most likely 4.4 - 6.5 m, with some variation along strike. Slip in the most recent earthquake at EPM may have been ~ 6.5 m, and preferred estimates of the cumulative slip in the past two, three and four earthquakes at EPM are ~ 12 m, ~ 18 m and ~ 23 m. The slip rate over the four most recent earthquake cycles in EPM was 12.5 mm/yr (range: 10.3 - 13.6 mm/yr) and is comparable to a previously published slip rate at Christmas Canyon West over the same period. The slip rate in PKV over the past three complete earthquake cycles is slower, about 4.2 - 7.7 mm/yr. The faster slip rate at EPM and Christmas Canyon West than in PKV may result from extension that is occurring in Searles Valley.

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