Slip Model and Co‐Seismic Displacement Field Derived from Near‐Source Strong Motion Records of the Lushan Ms7.0 Earthquake on 20 April 2013

Abstract

Near-source co-seismic displacement field of the 20 April 2013 Ms7.0 Lushan, Sichuan earthquake is estimated from digital strong-motion records after correction for their baseline errors using an improved empirical method and compared with the GPS observations. Furthermore, different slip models of the earthquake are inverted from the GPS and strong-motion based displacement data separately and jointly, which are in good agreement. Both show that the earthquake is dominated by the thrust mechanism (also a few left-lateral dislocations). The maximum horizontal and vertical co-seismic displacements reached 4.9 cm and 4.4 cm at station 51YAM and 51QLY, respectively. The fault slips are mainly distributed around the first event and in an area of about 30 km along the strike and 25 km along the dip. The moment magnitude is estimated to be Mw6.7, and the peak slip is about 1.14 m for strong motion data and 1.09 m for GPS. The surface rupture should be very small. Finally, we discuss the minimum requirements on the strong-motion data that ensure a reliable recovery of the co-seismic displacement data and corresponding problems in the current strong-motion networks in China.