3Dvp and Vs models of southeastern margin of the Tibetan plateau from joint inversion of body-wave arrival times and surface-wave dispersion data

作者：Lina Gao,Haijiang Zhang,Huajian Yao,Hui Huang

摘要：A new 3D velocity model of the crust and upper mantle in the southeastern(SE) margin of the Tibetan plateau was obtained by joint inversion of body-and surface-wave data. For the body-wave data, we used 7190 events recorded by 102 stations in the SE margin of the Tibetan plateau. The surface-wave data consist of Rayleigh wave phase velocity dispersion curves obtained from ambient noise cross-correlation analysis recorded by a dense array in the SE margin of the Tibetan plateau. The joint inversion clearly improves the v S model because it is constrained by both data types. The results show that at around 10 km depth there are two low-velocity anomalies embedded within three high-velocity bodies along the Longmenshan fault system. These high-velocity bodies correspond well with the Precambrian massifs, and the twolocated to the northeast of 2013 M S7.0 Lushan earthquake are associated with high fault slip areas during the 2008 Wenchuan earthquake. The aftershock gap between 2013 Lushan earthquake and 2008 Wenchuan earthquake is associated with low-velocity anomalies, which also acts as a barrier zone for ruptures of two earthquakes. Generally large earthquakes(M≥5) in the region occurring from2008 to 2015 are located around the high-velocity zones,indicating that they may act as asperities for these large earthquakes. Joint inversion results also clearly show that there exist low-velocity or weak zones in the mid-lower crust, which are not evenly distributed beneath the SE margin of Tibetan plateau.

發文機構：School of Geoexploration Science and Technology Laboratory of Seismology and Physics of Earth’s Interior National Geophysical Observatory at Mengcheng Department of Earth

關鍵詞：面波頻散青藏高原聯合反演S模型南緣體波時間三維速度模型Joint inversion - Body wavesSurface waves Aftershock gapThe southeastern margin of Tibetan plateau

分類號： P313.2[天文地球—固體地球物理學][天文地球—地球物理學]P631.443[天文地球—地質礦產勘探][天文地球—地質學]