Estimation and Comparison of Seismic Hazard Parameters for National Capital Region of India: using an Updated Earthquake Catalogue

Abstract

Delhi, situated in seismic zone class IV with a peak ground acceleration of 0.24 g, is highly prone to seismic activity. This study characterizes the seismicity of the Delhi region (28.70° N and 77.10° E) by considering a radial extent of 350 km around New Delhi. Earthquake data were collected from various sources and literature, resulting in a homogeneous earthquake catalogue with 574 events ranging from 3.0 M_w to 8.6 M_w, spanning the period from 1800 to 2024. Completeness analysis of the catalogue was conducted using the CUVI and Stepp's methods, estimating completeness periods for four magnitude groups: 3.0 ≤ M_w ≤ 3.99, 4.0 ≤ M_w ≤ 4.99, 5.0 ≤ M_w ≤ 5.99, and M_w ≥ 6.0. Seismic source details, including active faults, faults, and fault tectonics, were digitized using ArcGIS software, resulting in a seismotectonic map featuring four active faults (Pawalgarh Fault, Kotabag Fault, Yamuna Tear, and Kala Amb Tear Fault), 95 fault tectonics, and 3,175 minor and major faults. Seismic hazard parameters such as a-value, b-value, λ_m, M_max, and magnitude completeness were computed using standard methods. The a-values ranged from 3.13 to 4.12, and the b-value ranged from 0.65 to 0.83. The M_c value, determined using the Z-map in MATLAB, was found to be 3.5 M_w. This study is significant as it provides a comprehensive and updated catalogue that can be utilized for future hazard analysis of Delhi. The findings of this research will aid in the development of more accurate seismic hazard assessments and preparedness strategies for the National Capital Region, ensuring better mitigation of potential seismic risks.