基于地震震源机制的青藏高原现今构造应力场反演OA

Based on the MSATSI method with 1°× 1° grid resolution,we inverted the present-day tec-tonic stress field of the Qinghai-Xizang plateau.The results show that:1)The focal mechanisms are predominantly strike-slip and thrust types,with 72.70％of P-axes and 58.97％of T-axes plunging less than 30°,indicating that the Qinghai-Xizang plateau is dominated by horizontal compression and shear stress.2)The stress shape ratio R is significantly higher at the plateau margins than in the inte-rior,with 76.21％of maximum principal compressive stress axes(σ1)plunging less than 15° and tren-ding overall NNE-SSW.3)The maximum horizontal stress(SHmax)of Qinghai-Xizang plateau rotates clockwise around the eastern syntaxis.In the shallow crust(0 to 10 km),SHmax direction aligns with GPS velocity fields and is controlled by active tectonics.SHmax of the northeast margin of Qinghai-Xi-zang plateau,northeast of the Longmenshan,rotates counterclockwise by 20° to 30° at 10 to 20 km depth,indicating decoupling between shallow and deep stress fields,likely associated with differential deformation mechanisms of upper strike-slip and deep thrust thickening.