Seismic Imaging of Shallow Depths using Ambient Noise Tomography in the Hyderabad Region, Eastern Dharwar Craton, India

Abstract

ABSTRACT Hyderabad and its surrounding region are situated within Eastern Dharwar Craton, primarily composed of Archean granite. We use ambient noise tomography to obtain the 3-D shallow subsurface shear seismic velocity structure of 150 x 200 km2 area around Hyderabad. We used continuous waveforms that were recorded by a digital seismic network with 10 three-component broadband seismographs from November 2020 to December 2021. Using the vertical component of waveforms, the Empirical Green’s functions (EGFs) have been estimated, and the group velocity dispersion curves in the time period range of 1.0–10 s have been extracted from these. We inverted these dispersion curves to estimate 3-D variation of shear wave velocity by using direct surface wave tomographic method. The results suggest that the subsurface velocity structure is heterogeneous. The shear wave velocity varies from 3.4 to 3.7 km/s in the shallow subsurface. The limited seismicity in this area is mostly confined to the boundary between high and low-velocity changes.