Coseismic displacement and movement velocity around the Lushan focal area, western Sichuan

Based on discontinuous GPS data from the micro-earthquake observatories before and after the Lushan earthquake in 2013, the coseismic displacement and velocity vector fields have been obtained around the Lushan focal area, western Sichuan. The coseismic displacement values range between 5.09 and 51.05 mm, with an average of 14.18 mm, and the movement velocities vary from 2.64 to 52.37 mm/a, with an average of 18.89 mm/a. Furthermore, the movement velocities of the secondary faults in the southern part of the Longmenshan fault zone have also been obtained in the light of velocity vector differences, including 49.66 ±3.90 mm/a for the back range fault, 79.58 ±3.33 mm/a for the central fault and 50.94 ±3.91 mm/a for the front range fault. The central fault exhibits dextral compressional movement, whereas the back range and front range faults display sinistral extensional movement. The authors conclude that the Lushan earthquake in 2013 may be interpreted as a thrusting event on the southeastern side of the southern part of the Longmenshan fault zone. The seismogenic structures are represented by the minor faults between the front range fault and Xinjin fault. The Lushan earthquake in 2013 only had an important effect on the southern part of the Longmenshan fault zone and the areas around the Lushan focal area.