A Seismic Transmission System for Continuous Monitoring of the Lithosphere

Abstract

The main objective of this thesis is to enhance earthquake prediction feasibility. We present the concept and the design layout of a novel seismic transmission system capable of continuously monitoring the Lithosphere for changes in Earth physics parameters governing seismic wave propagation. New-technology seismic vibrator sources (magnetic levitation vibrator, linear synchronous motor vibrator) transmit, in continuously repeatable fashion, mutually uncorrelated, low-frequency signals simultaneously from different source locations, over regional distances. The signals are retrieved at seismic stations by long-term (weeks, months) coherent stacking and correlation (matched filtering) with the emitted signal code. Any Earth parameter changes along a propagation path, potentially representing earthquake preparation activity, will show up as time-lapse changes in the received signals. We model spatial static stress variation, attenuation, and anisotropy as medium-contrast-source perturbations in an isotropic, inhomogeneous medium. The potential earthquake preparation zone (EPZ) is to be mapped and characterized by means of ray-tracing and contrast-source inversion methods. Successful EPZ-evolution imaging should contribute to our understanding of earthquake processes, and may yield earthquake precursor statistics for issuing realistic earthquake warnings based on a tolerable false-alarm rate. In addition, the system may be used in general seismic tomography, and in reservoir parameter monitoring for gas, oil, and water resource management.