Surface Wave Dispersion Study of Nepal Himalayas

Mandal, Anmol Raj (2021) Surface Wave Dispersion Study of Nepal Himalayas. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Anmol Raj Mandal (16MS016)) 16MS016_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (33MB)

Abstract

We have used fundamental mode Rayleigh waves to calculate the group velocity dis- persion in the Nepal region. The data was taken from 114 stations in the Nepal area consisting of a closely spaced seismic array and some other stations in the area. We used 55 regional earthquakes with Magnitude 5 or higher. Using the dispersion curves, we performed tomographic inversion to calculate the dispersion of the entire region. We then extracted the dispersion curves for di�erent stations from 15-70 sec- onds and used them to get 1-D shear velocity models of the region. Our study aligns well with the previous studies in the region and shows the variation in the shear wave velocity structure in the region. The study suggests a Moho depth of around 40-50 Kms in the Nepal region which increases from the south to the north and goes up to around 80 Kms in the Tibet region. We suspect the presence of a LVL in the Tibet region which is visible but not prominent in our models. A low shear wave velocity is observed near the surface in the southern parts of Nepal. v

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