Ambient Noise Cross-Correlation and Surface Wave Dispersion of South India Region

Abstract

The peninsular part of the Indian continent (South India) is an important region because of the presence of various geological units. This thesis work focuses on implementing seismic interferometric techniques to ambient seismic noise recorded using broadband seismometers along the East-West profile of South India. Similar to optical interferometry, seismic interferometry (SI) gives us the detailed interior structure of the Earth by analysing the interference pattern of seismic waves. These interference patterns are obtained using the cross-correlation of seismic traces with one another. The seismic interferometric study helps to obtain the tomographic image of the Earth. This will reconstruct the image of velocity variation in the region of interest. The SI is a vital method for understanding the seismically quiet areas. With the help of this method, one can extract Green’s function from ambient noise recorded on the Earth’s surface, then the group or phase velocity computation and at last, the tomographic imaging. The tomographic imaging involves producing the phase and group velocity maps. In our work, we obtained the velocity maps for a period range between 3 sec and 15 sec, the group velocity varied from 2.99 km/s to 3.15 km/s and phase velocity varied from 2.9 km/s to 3.15 km/s. But this period range and less variation in group/phase velocity were unable to produce high resolution tomographic image of the region of interest.