Updated Vertical and Horizontal GPS Velocity Field in Bangladesh
Abstract
We compute an updated GPS velocity field for Bangladesh and its adjacent region using the latest available dataset from a suite of 30 GPS receivers. Previous GPS velocity field model from Bangladesh used dataset obtained in 2003-2013. Here, we use an up to date dataset through 2019, including preliminary newly installed stations from the Indo-Burman mountain range. This suite of 30 receivers cover the deltaic country of Bangladesh, which lies near the junction of the Indian Shield, the Himayalan collision belt and the Indo-Burman subduction zone.
The crust of the Indian Shield thins southeastward in Bengal Basin across the hinge zone of an early Cretaceous continental margin. The thin continental and/or oceanic crust of the Bengal Basin beyond the Hinge Zone is overlain by the southwest prograding Ganges-Brahmaputra Delta (GBD) creating a total sediment thickness of up to 19-20 km. The heavily-sedimented GBD is being overridden from the north by the Shillong Massif, a 2-km high basement-cored anticlinorium exposing Indian Shield, and from the east by the accretionary prism of the Indo-Burma wedge. The soft, oblique collision of the Burma platelet with the Bengal basin and the GBD has built a large accretionary prism that prism extends westward up to half way across the GBD. Previous work have shown that the GPS velocity field in the region is related to multiple processes: (1) Subsidence of the GBD from compaction and isostasy that increases seaward from the Hinge Zone. (2) Seasonal signals due to elastic vertical deformation from the weight of >100GT water impounded during the monsoon. (3) The horizontal component quantifies the shortening and lateral motion between the GBD and both the Indo-Burman wedge and Shillong Massif and is consistent with elastic deformation above a locked, shallowly dipping megathrust. The longer times series presented here are more accurate, particularly for the vertical component and can be used to advance our understanding of the prevailing geological processes in the region.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T13F0250O
- Keywords:
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- 8110 Continental tectonics: general;
- TECTONOPHYSICS;
- 8122 Dynamics: gravity and tectonics;
- TECTONOPHYSICS;
- 8169 Sedimentary basin processes;
- TECTONOPHYSICS;
- 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS