The Western margin of the Indian sub-continent that hosts one of the world’s largest escarpments, called the Western Ghats (WG), is a collage of diverse geological formations with different structural and physical properties. Characterizing upper mantle seismic anisotropy offers insights into the mantle deformation and its role in the evolution of such regions. In this study, we measured the upper mantle anisotropy using shear wave splitting analysis of SK(K)S and PK(K)S waveforms recorded at 17 broadband seismological stations located along and in the vicinity of the WG. Results indicate that the fast axis polarization directions are primarily in the NE-SW direction, with delay times varying from 0.3 s to 1.8 s. This direction is parallel to the Absolute Plate Motion of the Indian sub-continent, suggesting that shear at the base of the lithosphere is the dominant mechanism for anisotropy along the WG. E-W oriented anisotropy at stations close to the west coast, especially in the northern part of the WG can be associated with lithospheric stretching along the west coast, associated with the rifting process. Further, the coast-parallel fast axis polarization directions (N-S, NNW-SSE), with delay times varying from 0.6 s to 1.2 s, at stations away from the coast, could be due to the edge flow associated with transition from a thinner to a thicker lithosphere. In addition, we model the variation in splitting parameters at station PCH in the Southern Granulite Terran in terms of two-layer anisotropy, with an E-W orientation in the upper layer and a NE-SW one in the lower layer. The variable fast axis polarization directions from coast perpendicular to coast parallel at stations close and away from the west coast of the Indian sub-continent imply different rifting episodes.

印度次大陆的西部边缘拥有世界上最大的悬崖之一，称为西高止山脉 (WG)，是具有不同结构和物理特性的多种地质构造的拼贴。表征上地幔地震各向异性提供了对地幔变形及其在这些地区演化中的作用的见解。在这项研究中，我们使用 SK(K)S 和 PK(K)S 波形的剪切波分裂分析测量了上地幔各向异性，这些波形是在位于 WG 沿线和附近的 17 个宽带地震台站记录的。结果表明快轴极化方向主要在NE-SW方向，延迟时间从0.3 s到1.8 s不等。这个方向平行于印度次大陆的绝对板块运动，表明岩石圈底部的剪切是沿 WG 各向异性的主要机制。靠近西海岸的台站的 EW 方向各向异性，特别是在 WG 的北部，可能与沿西海岸的岩石圈伸展有关，与裂谷过程有关。此外，在远离海岸的站点，与海岸平行的快轴极化方向（NS、NNW-SSE）的延迟时间从 0.6 s 到 1.2 s 不等，这可能是由于与从较薄到较厚的岩石圈。此外，我们根据两层各向异性对南部 Granulite Terran 站 PCH 分裂参数的变化进行建模，上层为 EW 方向，下层为 NE-SW 方向。