1-D shear wave velocity structure beneath North India using surface wave dispersion study

The seismological data recorded at our four semi-permanent broadband seismographs installed by the CSIR-NGRI, Hyderabad, Telangana in the Aravalli mobile belt (AMB) and Rajasthan craton in the northwest Indian shield during the period 2014-2016 are used in the study. The 16 selected regional Indian earthquakes of M-w 5.5-7.8 that occurred in the North India region recorded at the four seismic stations are used to compute the surface wave (both Rayleigh and Love waves) group velocity dispersion characteristics and average 1-D regional shear wave velocity (V-s) structure beneath the North India which covers the northern part of India between the whole Himalayan region and Rajasthan craton including AMB. First, we compute Rayleigh waves (at 7-87 s) dispersion curves and Love waves (at 7-82 s) group velocity dispersion curves by utilizing the standard frequency time analysis (FTAN) of 3-component broadband data recorded at these four 3-component broadband seismic stations. After that, using the logarithmic stacking technique, we compute the Bnal average stacked fundamental mode dispersion curves of surface waves (both Love and Rayleigh waves) for our study area. Then, we Bnally invert the Bnal average dispersion curves of surface waves (both Love and Rayleigh waves) to compute the average one-dimensional regional shear velocity structure beneath North India. Our modelling result in North India suggests a two-layered crustal structure with a crustal thickness of 39 km. The thickness of the Brst crustal layer (upper crust) is 20 km with a shear wave velocity (V-s) of 3.30 km/s. On the other hand, the second crustal layer (lower crust) marks a 19-km thickness with a V-s of 3.70 km/s. Our modelling result suggests that the V-s of the upper mantle is found to be 4.35 km/s below the study region.