Date of Award

Spring 2025

Project Type

Thesis

Program or Major

Electrical and Computer Engineering

Degree Name

Master of Science

First Advisor

Kent A Chamberlin

Second Advisor

Richard A Messner

Third Advisor

Wayne J Smith

Abstract

The purpose of this investigation is to determine whether or not there are any identifiable properties or characteristics in the measurements of the atmospheric electrical potential gradient prior to California earthquakes that could qualify as a precursor signal. Scientists from around the world have reported anomalous behavior in the potential gradient before earthquakes for more than 130 years. The only two previous reports on this subject involving California earthquakes and the potential gradient were inconclusive and based upon limited data. This present study examines an eleven-year database (2009-2019) of the potential gradient observed in the desert regions surrounding Ridgecrest, California in Kern County. Only ten earthquake cases with coincident and available potential gradient measurements were found suitable for further study. Inspection of the time series records did not reveal any abnormalities that could be conclusively attributed to electromagnetic noise generated by earthquakes. Further analysis involving regression curve fits to the diurnal variability of the potential gradient signal, assessment of the potential gradient residuals, scrutiny of histograms of the residuals, autocorrelation, and spectral analysis failed to detect an undeniable earthquake precursor signal. These findings do not confirm research reports from other countries that significant decreases in the potential gradient occur prior to earthquakes. A possible explanation for the disagreement may be in the type of earthquake faults in place. California earthquakes are associated with strike-slip faulting while the earthquakes in the countries reporting earthquake related potential gradient anomalies are subject to thrust faulting.

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