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Active faulting in apparently stable peninsular India: Rift inversion and a Holocene‐age great earthquake on the Tapti Fault
Author(s) -
Copley Alex,
Mitra Supriyo,
Sloan R. Alastair,
Gaonkar Sharad,
Reynolds Kirsty
Publication year - 2014
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2014jb011294
Subject(s) - geology , seismology , alluvial fan , foreland basin , seismic gap , fault (geology) , rift , fault scarp , holocene , strike slip tectonics , thrust fault , seismic hazard , sedimentary rock , tectonics , paleontology
We present observations of active faulting within peninsular India, far from the surrounding plate boundaries. Offset alluvial fan surfaces indicate one or more magnitude 7.6–8.4 thrust‐faulting earthquakes on the Tapti Fault (Maharashtra, western India) during the Holocene. The high ratio of fault displacement to length on the alluvial fan offsets implies high stress‐drop faulting, as has been observed elsewhere in the peninsula. The along‐strike extent of the fan offsets is similar to the thickness of the seismogenic layer, suggesting a roughly equidimensional fault rupture. The subsiding footwall of the fault is likely to have been responsible for altering the continental‐scale drainage pattern in central India and creating the large west flowing catchment of the Tapti river. A preexisting sedimentary basin in the uplifting hanging wall implies that the Tapti Fault was active as a normal fault during the Mesozoic and has been reactivated as a thrust, highlighting the role of preexisting structures in determining the rheology and deformation of the lithosphere. The slip sense of faults and earthquakes in India suggests that deformation south of the Ganges foreland basin is driven by the compressive force transmitted between India and the Tibetan Plateau. The along‐strike continuation of faulting to the east of the Holocene ruptures we have studied represents a significant seismic hazard in central India.