Crustal Structure Of The Western Himalaya

Abstract

Seismic waveforms recorded during quiet periods (i.e., no earthquakes) is known as ambient noise. It is generated by natural (e.g., oceanic gravity waves) or anthropogenic sources. I processed and modeled the ambient noise data from the 15 seismic networks in the western Himalayas to compute the seismic velocity structure of the underlying crust. The ambient noise processing data can be divided into 4 steps. (1) Processing of raw data, (2) cross-correlation and stacking, (3) measurement of group velocity using dispersion curves, (4) inversion of dispersion curve. I used the Multiple Filter Technique (MFT) method for the surface wave dispersion of the fundamental mode Rayleigh wave. The inversion of the dispersion curves provides a crustal velocity model. The velocity model shows a velocity reduction between 10 and 30 km depth that indicates a Low-Velocity Layer (LVL) which may indicate the presence of partial melt or aqueous fluid or both.