Comparison of Crustal Stress and Strain Fields in the Himalaya–Tibet Region: Geodynamic Implications

Abstract

The Himalaya–Tibet region represents a complex region of active deformation related to the ongoing India–Eurasia convergence process. To provide additional constraints on the active processes shaping this region, we used a comprehensive dataset of GNSS and focal mechanisms data and derived crustal strain and stress fields. The results allow the detection of features such as the arc-parallel extension along the Himalayan Arc and the coexistence of strike-slip and normal faulting across Tibet. We discuss our findings concerning the relevant geodynamic models proposed in the literature. While earlier studies largely emphasized the role of either compressional or extensional processes, our findings suggest a more complex interaction between them. In general, our study highlights the critical role of both surface and deep processes in shaping the geodynamic processes. The alignment between tectonic stress and strain rate patterns indicates that the crust is highly elastic and influenced by present-day tectonics. Stress and strain orientations show a clockwise rotation at 31°N, reflecting deep control by the underthrusted Indian Plate. South of this boundary, compression is driven by basal drag from the underthrusting Indian Plate, while northward, escape tectonics dominate, resulting in eastward movement of the Tibetan Plateau. Localized stretching along the Himalaya is likely driven by the oblique convergence resulting from the India–Eurasia collision generating a transtensional regime over the Main Himalayan Thrust. In Tibet, stress variations appear mainly related to changes in the vertical axis, driven by topographically induced stresses linked to the uniform elevation of the plateau. From a broader perspective, these findings improve the understanding of driving crustal forces in the Himalaya–Tibet region and provide insights into how large-scale geodynamics drives surface deformation. Additionally, they contribute to the ongoing debate regarding the applicability of the stress–strain comparison and offer a more comprehensive framework for future research in similar tectonic settings worldwide.