Simultaneous Sources-Based Elastic Wave Local-Scale Traveltime Inversion

Wave equation-based traveltime inversion is a method that uses traveltime information to obtain the low-wavenumber components of subsurface velocity models. This helps create a reliable initial model for full waveform inversion (FWI). However, this method usually requires identifying the first arrival waves or specific seismic events to calculate the traveltime differences between the observed and synthetic data. When working with multiple seismic events, such as those from elastic wavefields or simultaneous sources-based seismic data, it becomes difficult to obtain the low-wavenumber components of velocity models by traveltime inversion. In this letter, we propose a simultaneous source-based elastic wave local-scale traveltime inversion (SS-ELTI) method. This method utilizes both P-wave and S-wave data, along with local-scale traveltimes from various seismic events generated by simultaneous sources. This approach enables the simultaneous inversion of the low-wavenumber components of both P-wave and S-wave velocity parameters. Numerical tests demonstrate that the proposed SS-ELTI method can effectively reduce the computational costs and mitigate the cycle-skipping problem of elastic full waveform inversion (EFWI).