Abstract The crust-lithosphere structure, especially the discontinuities such as Moho and lithosphere-asthenosphere boundary (LAB), is important in the investigation of geodynamic process implications and tectonic evolution of the lithosphere and regional seismic activity. We stacked the S receiver functions from 51 permanent broad-band stations to investigate the crust-lithosphere structures beneath the southeastern edge of the Tibetan Plateau and further discussed the mechanism of lower-crust earthquakes, the regional tectonics deformation characteristics, and the relationship between the two discontinuities and seismicity in this region. The results show that the Moho depth increases from 40 to 52 km beneath the Sichuan Basin to 56–74 km on the both western side of the Longmenshan (LMS) fault and Anninhe-Zemuhe fault. The LAB depth ranges from 130 to 170 km beneath the Sichuan Basin, and a shallow belt ranges from 100 km to 130 km around the Sichuan Basin. On the Moho depth contour map, 374 moderate earthquakes that accounted for 72.2%, corresponding to the depth range of 44–52 km and 60–68 km on the both sides of a narrow strip (longitude 102°~104°). On the LAB depth contour map, 321 earthquakes accounted for 62.15% in the depth range of 130–150 km. The variation of LAB corresponds to the increasing crustal thickness, intensive lower crustal earthquakes (hypocenters about 60 km and magnitude 4.0 ≤ Ms. ≤ 4.9) and surface abrupt elevations. It implied that Normal strong earthquakes generate the lower crustal earthquakes or aftershocks that resulted in the shear zones where fluid-induced metamorphic transformations, the eclogitization of dry granulite, and further affect the crustal thickness and deformation to control the spatial distribution of deep faults and seismicity.

中文翻译：

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青藏高原东南缘地壳岩石圈结构与地震活动的关系

摘要 地壳-岩石圈结构，特别是莫霍面和岩石圈-软流圈边界（LAB）等不连续面，对于研究岩石圈的地球动力学过程意义和构造演化以及区域地震活动具有重要意义。将 51 个永久宽带台站的 S 接收函数叠加，研究青藏高原东南缘地壳-岩石圈结构，并进一步讨论了下地壳地震发生机制、区域构造变形特征以及该地区有两个不连续性和地震活动。结果表明，莫霍面深度从四川盆地下方的 40~52 km 增加到龙门山（LMS）断裂和安宁河-泽木河断裂西侧的 56~74 km。LAB 深度在四川盆地以下为 130 至 170 公里，四川盆地周围为浅带，范围为 100 至 130 公里。在莫霍面深度等值线图上，374次中等地震，占72.2%，对应一条窄带（经度102°~104°）两侧44-52公里和60-68公里的深度范围。在LAB深度等高线图上，130～150km深度范围内发生321次地震，占62.15%。LAB 的变化对应于地壳厚度的增加、强烈的下地壳地震（震源约 60 公里，震级 4.0 ≤ Ms. ≤ 4.9）和地表突然高程。这意味着正常强地震产生下地壳地震或余震，导致剪切带发生流体诱发变质转变，干燥麻粒岩的榴辉岩化，