Shallow structure of the Longmenshan Central Fault Zone based on dense seismic array

Three short-period dense arrays, each of which recording continuous data of nearly one month, are deployed by China University of Geosciences (Beijing) at Hongkou Town, Beichuan County and Pingtong Town in 2017, 2019 and 2020, respectively. The combination of different seismological methods is effectively and successfully applied for resolving the high-precision structure and analyzing the fault activity of Longmenshan central fault zone. By using ambient noise tomography, Rayleigh wave attenuation tomography, horizontal-to-vertical spectral ratio (HVSR) and fault zone trapped waves (FZTW) analysis, we propose a new structure model for the Longmenshan central fault zone. The north of Beichuan may be considered as a V-shape asperity, with the southwestern end of Beichuan fault and Tangwangzhai nappe converging at Beichuan area. Then the Tangwangzhai nappe released stresses jointly with the Beichuan fault during the Wenchuan earthquake rupture process.