Teleseismic Receiver Functions Constraint on the Structure of the Indo-Burma Subduction System
Abstract
The Indo-Burma subduction system comprises the Indian Ocean plate subducting beneath the nonrigid Burma microplate. In the process, the largest river delta ( 19 km sediment thickness) in the world, the Ganges-Brahmaputra Delta located on the Indian Plate is being accreted onto the Burma plate resulting in a broad ( 200 km wide) subaerial accretionary prism. A recent GPS study indicates that this extensive subduction system is locked and is therefore capable of a large Mw>8.2 earthquake that could have devastating effects for this densely populated region. As part of an effort to improve our understanding of the structure of this extreme subduction system and its related earthquake hazard, the collaborative Tripartite Project is deploying the Bangladesh-India-Myanmar Array (BIMA). We have installed 28 broadband seismometers with dense (5-10 km) spacing across Bangladesh. A similar number of seismometers will be deployed in Myanmar later this year followed by instrumentation in India to complete a 100 broadband station transect across the plate boundary zone with the main objective of imaging active structures. Analysis of teleseismic events ( 30˚ - 90˚) with M> 5.5 across the seismic array will help illuminate crustal and upper mantle structures of the Indo-Burma subduction system, including major lateral discontinuities in the Ganges-Brahmaputra Delta sediments, sediment-crust interface, Moho depths, and the geometry and connectivity of the megathrust and the detachment(s) within the thick sedimentary package. Variations in receiver functions with backazimuth will provide additional constraints on the anisotropy and geometry of shear zones in the subduction zone. We will present preliminary results of receiver functions computed from waveforms recorded across Bangladesh.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T11H0238A
- Keywords:
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- 8102 Continental contractional orogenic belts and inversion tectonics;
- TECTONOPHYSICSDE: 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICSDE: 8170 Subduction zone processes;
- TECTONOPHYSICS