Distributed Acoustic Sensing for Imaging Near-Surface Geology and Monitoring Traffic at Garner Valley, California

Distributed Acoustic Sensing (DAS) is a relatively new technology that uses a fiber-optic cable as a sensor. DAS got its start in the energy industry for borehole monitoring and more recently has started being used in horizontal arrays. The DAS technique senses strain rates every 1 m over distances of up to 100 km of cable length with sampling rates as fast as 100 kHz. This dissertation uses a horizontal DAS array in Southern California to evaluate the use of DAS for imaging near-surface geology and monitoring traffic.;The first chapter uses Multichannel Analysis of Surface Waves to evaluate the response of DAS to surface waves. Dispersion curves from the DAS array match well with results from 1) other instruments at the site, 2) ambient noise correlation functions using the same DAS array, and 3) previous studies at the site. The second chapter uses the DAS array to create 2D tomographic images of the site for a number of pixel sizes and the directional sensitivity of DAS is discussed. The third chapter explores the possibility of using DAS for traffic monitoring. Vehicle counts, relative amplitudes, and velocities are identified and prove DAS could be used for traffic monitoring.