Estimating short-term slip rates on intraplate faults around Shillong plateau (N-E India) and their geodynamic implications

Parida, Binayak (2023) Estimating short-term slip rates on intraplate faults around Shillong plateau (N-E India) and their geodynamic implications. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Binayak Parida (18MS064)) Thesis_18MS064.pdf - Submitted Version Restricted to Repository staff only Download (3MB)

Abstract

Earthquakes in the Himalayan region occur due to the ongoing convergence between India and Eurasia. Northeast Himalaya is considered to have high seismic hazard as most of its region lies in the seismic gap. GPS measurements have proved to be extremely useful in quantifying the crustal deformation studies and assessing seismic hazard in a region. Continuous GPS measurements have helped us to estimate secular motion, which is used to understand earthquakes and other geodynamic processes. In the present work, I have independently characterized the faults present in the adjoining region of the Shillong plateau using available literature and GPS measurements of crustal deformation. Dislocation theory was used, which assumes that the Earth is a homogeneous isotropic elastic half-space, and a grid search approach was applied to estimate the slip rate and locking depth of each fault. The best-fit elastic dislocation model suggests an average right lateral slip of 4 mm/yr and a locking depth of 20 Km of the Kopili Fault. In a similar manner we found out that Dauki and Naga faults are both reverse thrust faults with slip rates of about 4 mm/yr and 6 mm/yr, respectively, and locking depths of 25 Km and 10 Km. I have also estimated the maximum magnitude (MM) earthquake and its recurrence period for each fault using empirical relations which dependent on fault geometry parameters such as length, width, and area, as well as fault slip rate. I analyzed that the Kopili Fault has an average MM of Mw7.8 with a recurrence period of approximately 2500 years, the Dauki Fault has an average MM of Mw8.0 with a recurrence period of approximately 750 years, and the Naga Thrust has an average MM of Mw7.6 with a recurrence period of approximately 380 years.

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