Effects of sedimentary layer on earthquake source modeling from geodetic inversion

Ground deformation as observed with GPS or InSAR has been broadly inverted in constraining source parameter of earthquakes. However, for earthquakes occurring beneath sedimentary basins, the very slow sub-surface shear velocity (v_S, down to 200 m/s) may cause substantial bias to earthquake source inversion if simple crustal models are used. For Bohai basin, Sichuan basin and rock-sites, we test effects of sub-surface shear velocity structure on ground deformation, and find that up to a factor of 2 overestimate of seismic moment could be generated by the basin structures. Therefore, the very slow sub-surface velocity has to be taken into account before accurate source inversion can be applied.