Date of Award

12-2019

Document Type

Thesis

Degree Name

Master of Science in Earth and Environmental Sciences

Department

Geological Sciences

First Reader/Committee Chair

Sally McGill

Abstract

In this study, a paleoseismic trench with limited age constraints that was previously excavated in 1990 across the central Garlock Fault near Christmas Canyon, in Searles Valley, California, was reopened to take advantage of new advances in luminescence dating techniques to investigate potential temporal variability in earthquake recurrence on the Garlock fault and to analyze previously unexposed older earthquake evidence. The trench exposed interbedded alluvial sand and pebble-gravels, with well-sorted, rounded, lacustrine sand from the most recent highstand of pluvial Lake Searles present at the base of the trench. Preliminary findings suggest at least 10 surface rupturing earthquake events occurred during the 10 k.y. time period exposed in the trench. To provide age constraints on the paleo-surface-rupturing events from the new trench, 54 luminescence samples were collected and the single-grain luminescence dating technique post- - was employed. The ages indicated that 7 events have occurred in the past ~7.2 ka, with at least 3 additional events in the more poorly stratified deeper section of the trench. This suggests a recurrence interval of ~1000 years. Event pattern seen at this trench did not exactly replicate the same pattern at other paleoseismic sites along the Garlock Fault. The most recent event seen at this trench occured within the same time period as the most recent events seen at the other paleoseismic sites on the central Garlock Fault.

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