Exploring a region below a surface of the Earth using ambient seismic interface waves

摘要

A passive method for exploring a region below the surface of the earth comprises using a plurality of sensors to record ambient seismic interface waves in a frequency range whose lower limit is greater than 0Hz, and whose upper limit is less than or equal to substantially 1Hz. In one method each of the sensors is located in turn at a plurality of locations. The data are processed 41-44 to obtain a measure of the energy in a frequency band within the frequency range. In another method, data in at least one time sub-interval is selected for processing based on data quality. The energy measure may be calculated 44 by integrating the spectrum in the frequency domain over a desired frequency range. The resulting calculated energy provides information about the region of the earth being explored. The sensors may be sensitive to three orthogonal components. In another method, data recorded at a pair of locations is cross-correlated to derive wave dispersion data. In another method, recordings 40 may be made simultaneously by all sensors and normalisation of data is unnecessary.