Exploración sísmica de refracción mediante ruido sísmico

Abstract

In this study, a seismic refraction profile was obtained using seismic noise records. The waveforms were recorded on a refraction line located west of Mexico City. The line consists of a linear array of 24 vertical geophones spaced 2 meters apart and a record length of 175 minutes. The virtual refraction profile was constructed from the cross-correlation of the seismic noise records from the 24 geophones. Each virtual refraction trace was obtained by stacking the correlations for all time windows between pairs of stations. In signal processing, different normalization applications were tested, with the aim of recovering the arrival of the P wave. Three seismic refraction profiles were calculated corresponding to virtual sources located in the center and ends of the line. To evaluate the recovery of the P waves acquired in this way, a spectral analysis of the cross correlations was performed to rule out the use of surface waves in synthetic seismograms. The virtual profiles obtained were compared with the conventional seismic refraction profiles, showing clearly the recovery of the first arrivals of the P wave, even improving the definition of the traces of conventional refraction. In addition, to complement the study, an F-K analysis was performed to discriminate surface waves and obtain only body waves.