Estimate of shear wave velocity, and its time-lapse change, from seismic data recorded at the SMNH01 station of KiK-net using seismic interferometry

This study uses the deconvolution of small earthquakes registered in the SMNH01 station of KiK-net, one of the most important seismic networks which is located in Japan, to estimate effective shear wave velocities β, shear modulus μ, and quality factors Q, and to identify physical changes in the soil. This station has a borehole which is equipped with triaxial accelerometers installed at the surface and at 100 m of depth. By deconvolving seismic events registered at surface and at 100 m of depth, we obtain physical parameters. To interpret deconvolved waves, we use a one dimensional (1D) layered medium. Based on changes observed in amplitudes and arrival times of deconvolved waves, we identify time-lapse variations in shear wave velocities (maximum change in δβ/βδβ/β=3.8%) and shear modulus (maximum change in δμ/μδμ/μ=7.8%). The variations in shear wave velocities detected at station SMNH01 are mainly due to the combined influence of precipitation and recurrent seismic events.

► We model waves using a 1D layered medium. ► We obtain theoretical deconvolutions and the attenuation operator. ► We get velocities by deconvolving seismic data of KiK-net. ► We interpret deconvolved data using theoretical deconvolutions. ► We identify time-lapse changes in shear wave velocities.