Chapter 14 Seismicity of the Andaman–Nicobar Islands and Andaman Sea

Abstract

AbstractThis chapter examines the history and distribution of seismicity across the Andaman–Nicobar island arc and Andaman Sea. Fundamental differences between the Andaman section of the subduction zone and the Sumatra–Java section to the south help to explain the nature of the deformation. Magnitudes of displacements varied along-strike from uniform dip-slip on the southern (Sumatran) segment to dip-slip and strike-slip components on the Andaman and Nicobar segment. The Andaman section has a more steeply dipping slab and a thicker sediment cover compared to the Sumatra region where coupling with the overlying plate is stronger. Temporal and spatial patterns of seismicity in the Andaman Sea spreading centre are consistent with normal faulting and c. 25 year cycles of dyke injection are considered responsible for the bulk of the spreading.