Near-Surface Shear Velocities in Diverse Geological Segments of India.

In this paper we investigate the near-surface shear velocities beneath 144 broadband seismic stations of India that span diverse geological terrains, using nearly 37,635 good quality (SNR > 2.5) three-component waveforms from 3849 earth-quakes. The results suggest lower shear velocities beneath regions of large sedimen-tation, with the lowest in the range of ~1 km/s observed for the Indo-Gangetic plains. These low velocity estimates show a dependence on frequency, implying velocity changes with depth. Segments that represent the Precambrian shield reveal high shear velocities in the range of 3.2 to 3.4 km/s, akin to global observations. The mountain ranges that constitute the Himalaya and southern Tibet have intermediate velocities primarily ranging from 2.8 to 3.0 km/s. Overall, the near-surface shear velocities seem to be correlated with the local geology and provide inputs for site-specific hazard assessment in terms of predicting strong ground motions due to scenario earthquakes. [ABSTRACT FROM AUTHOR]