Date of Award
2023-05-01
Degree Name
Doctor of Philosophy
Department
Geological Sciences
Advisor(s)
Marianne Karplus
Second Advisor
Aaron Velasco
Abstract
The continental collision between the Indian plate and the Eurasian plate at ~55 Ma (Molnar and Tapponnier, 1975) has uplifted the northern part of Nepal forming the Himalayas. This convergence of India and Eurasia produced intra-upper crustal shear zones and thickened the crust to its present thickness of 70 km (Molnar, 1988; Zhao et al, 1993). The convergence rate across the Nepalese Himalayas is estimated between 17-21 mm/yr. (Ader et al., 2012). Because of this convergence, the region has experienced large, devastating earthquakes, including the 1934 Mw~8.2 Nepal-Bihar earthquake (Dunn et al., 1939) and two recent earthquakes on April 25, 2015, Mw~7.8 (Gorkha earthquake) and May 12, 2015, Mw ~7.2 (Kodari earthquake) (Avouac et al, 2015). In June 2015, to study the Mw~7.8 Gorkha earthquake in Nepal, researchers from the University of Texas at El Paso, Oregon State University, University of California at Riverside, and Stanford University deployed seismometers at 46 sites around the rupture area of the Gorkha earthquake to record aftershocks in the region. This dissertation focuses on the analysis of this dataset to understand the nature of the earthquake, the damage it created, and the tectonic structure of the Himalayas in this region. Specifically, I present the data acquisition and quality of the aftershock recordings following Gorkha earthquake. Secondly, I conduct a site response study of the central Himalayas highlighting the resonance frequency distribution and amplification in different physiographic regions. I compare the observed damage from recent earthquakes with the site response of different regions with the hope of reducing future seismic damage in the area. In the last chapter, I present new P-wave and S-wave velocity models from local tomography. The primary aim of the dissertation is to gain insight into the structure of the Main Himalayan Thrust (MHT) fault and the region surrounding the Gorkha earthquake rupture area. This chapter describes the geological background and history of the Himalayas.
Language
en
Provenance
Recieved from ProQuest
Copyright Date
2023-05
File Size
p.
File Format
application/pdf
Rights Holder
Mohan Pant
Recommended Citation
Pant, Mohan, "Seismicity, Tectonics, And Site Response In The Nepalese Himalayas" (2023). Open Access Theses & Dissertations. 3883.
https://scholarworks.utep.edu/open_etd/3883