Seismicity of the Andaman–Nicobar Islands and Andaman Sea
Published:January 01, 2017
A. Carter, P. C. Bandopadhyay, 2017. "Seismicity of the Andaman–Nicobar Islands and Andaman Sea", The Andaman–Nicobar Accretionary Ridge: Geology, Tectonics and Hazards, P. C. Bandopadhyay, A. Carter
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This 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.
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The Andaman–Nicobar Accretionary Ridge: Geology, Tectonics and Hazards
Rocks exposed across the hundreds of islands that belong to the 800 km long Andaman–Nicobar archipelago provide a condensed window into the active subduction zone that separates the India–Australia plate from the over-riding Burma–Sunda plate. Despite a strategic and seismically active location the Andaman-Nicobar ridge has seen comparatively little research. This Memoir provides the first detailed and comprehensive account of geological mapping and research across the island chain and adjacent ocean basins. Chapters examine models of Cenozoic rifting of the Andaman Sea and the regional tectonic and seismogenic framework. A detailed critical review of the Andaman–Nicobar stratigraphy, supported by new data, includes arc volcanism and a description of Barren Island, India’s only active volcano. Seismic history and hazards and the impacts of the 2004 earthquake and tsunami are also described. The volume ends with an examination of the region’s natural resources and hydrocarbon prospects.