Surface-Wave Analysis and Inversion of Ambient Noise Recordings

Summary A new approach is proposed to estimate the S-wave velocity of the near surface (and its changes over time) from passive data. The method consists of 5D interpolation followed by surface-wave analysis and inversion. This allowed us to overcome the issue of velocity estimation in between detector cables avoiding the phase velocity tomography step. The method was tested on virtual shots generated by interferometry techniques applied on ambient noise recorded at the Valhall Life of Field Seismic permanent monitoring network. Maps of the phase velocities allowed identifying several geological features in the near surface. A time-lapse analysis was also performed and the changes in S-wave velocity shows correlation to the 4D time shifts from converted-wave data.