Upper-Mantle Attenuation Tomography Using Surface Waves Recorded by Regional 2D Seismic Arrays

3D attenuation tomography of the upper mantle is important for understanding the temperature and rheological structures of the Earth’s interior as well as the related geodynamic features and mechanisms. However, robust surface-wave attenuation tomography is still challenging due to the strong trade-off between the intrinsic attenuation and the scattering due to the complex effects of 3D wave-speed and density heterogeneities in the surface-wave amplitude records. Based on tracking surface-wave travel times and amplitudes from seismic array data, here we upgraded the theory of Helmholtz tomography by accounting for the scattering effects and present a new method called Helmholtz Multi-Event Tomography to invert for the variation of surface-wave attenuation. The synthetic inversions based on 3D forward simulations in anelastic media validate the effectiveness of our new method. We then demonstrated the resulting surface-wave attenuation model can be applied to an iterative depth inversion that reveals the 3D variation of intrinsic attenuation of the upper mantle. Our study provides an innovate and promise way to generate accurate and precise attenuation models of the upper mantle from surface-wave data with low computational cost.