TRANSLATIONS AND ROTATIONS IN LAYERED ELASTIC HALF SPACE DUE TO STATIC SHEAR DISLOCATION ON FINITE FAULT

Abstract

Earthquake-resistant design of underground structures like metro rail tunnels, building foundations, and pipelines requires availability of permanent displacements (translations & rotations) and deformations at a particular depth caused by an earthquake. However, current practices primarily focus on surface translations due to the scarcity of information on these internal displacements and deformations, potentially leading to underestimation of seismic loads on these civil engineering structures. There are some literatures which estimates these permanent displacements and deformations, but they are either computationally inefficient or mathematically too cumbersome. This study aims to overcome this limitation, by the development of efficient solutions for accurately estimating these earthquake-induced displacements and deformations in the internal layers of ground. This study uses the 'physics-based' techniques for estimating these displacements. It employs a kinematic shear dislocation on a finite fault source model, representing the medium as a horizontally layered semi-infinite elastic medium. Another motivation for this study is if we gather displacements from sensors in boreholes, we can use them for inversion to estimate the model of the source of earthquake. This estimated model can then be evaluated by predicting these displacements for the borehole's depth and comparing them with the actual data recorded at that spot. This process helps ensure the accuracy of the earthquake source model. As a case study, we estimated these displacements on the surface due to recently occurred Turkey Mw 7.8 earthquake which occurred on February 6, 2023.