Q tomography with ray and waves

Seismic wave propagation can be simulated using ray-based methods or wave-equation-based methods. Ray methods are based on high frequency approximation. Those methods work well in a geological setting with smooth velocity variation in the subsurface. However, ray-based methods can fail in imaging the complex media e.g., below or near salt, where wave-equation-based methods are known to be more robust for imaging. In this study, we examine the advantages of the wave-equation-based method over the ray -based method in the case of Q tomography in a complex setting. We employ a synthetic model that has salt bodies with rugose salt boundaries. Two attenuation anomalies are included: one is above the top of salt; the other one is close to the steep salt flank. We measure the attenuation effects from the spectral loss of the seismic events at near offsets (0 m - 600 m) and at mid offsets (600 m -1,200 m). We then do a least-squares inversion of the same measurements to update our Q model using ray- and wave-equation- based tomography. Through the numerical tests, we would like to study how the complex overburden impacts Q inversion differently in ray- and wave-equation based tomography.