Passive seismic monitoring to detect onset of ground failure hazard

Abstract

A method for monitoring Earth's subsurface for indication of ground failure includes processing signals detected by seismic sensors disposed proximate the area, by migrating a response of the sensors to each of a plurality of sub volumes. The migrated responses are summed over a first selected time interval. Events having amplitude exceeding an average amplitude over a second selected time interval longer than the first time interval are detected and their amplitudes are summed from within each of a plurality of substantially vertical column of the plurality of sub volumes. A two dimensional smooth surface is calculated based on the summed amplitudes, and a difference between the summed amplitudes and a value of the smoothed surface for each vertical column is calculated. A statistical measure of the difference values is calculated. Statistical measures that exceed a selected threshold are identified as advance indication of ground failure.