Reconstruction of the subsurface fault geometry across the Indo-Burman Ranges through an interdisciplinary approach

• Main Author: Sun, Huiwen
• Other Authors: Judith Hubbard
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Geology::Structural geology
• Online Access: https://hdl.handle.net/10356/156704
• Institution: Nanyang Technological University

The Indo-Burman Ranges (IBR) is the surface expression of the north-trending accretionary wedge resulting from the oblique subduction of the Indian Plate beneath the Burma Plate. Geodetic evidence showing active strain accumulation on the locked megathrust at the plate interface has highlighted its seismic potential which was previously overlooked due to the lack of major interplate ruptures since the 1762 Arakan earthquake. Though possibly affecting multiple densely populated cities overlying the megathrust, our geometrical understanding of the regional fault system remains minimal. In this study, we integrate the most up-to-date geological and geodetic studies and develop a structural cross-section that incorporates surface geology, stratigraphy and subsurface fault structures. The proposed fault model is characterized by a dual-ramp structure and a gently dipping décollement. We also extend our analysis from the east-west to the along-strike direction to explore the spatially variable fault properties that could possibly control the interseismic behavior of the megathrust. We analyze the spatial changes in the material properties of the fault, the temperature-dependent frictional stability of clay minerals and the location of fault ramps. Our results suggest a lack of strong spatial correlation between these factors and the zone of interseismic locking on the megathrust. Due to the limited data resolution and the complex nature of fault dynamics, we do not rule out the possible impacts of those fault properties on the interseismic fault behavior. Based on the proposed fault geometry and established earthquake rupture models, we discuss several possible earthquake rupture scenarios in the study region.