Probabilistic Seismic Hazard Assessment of Itanagar, Arunachal Pradesh, India: Insights into Tectonic Activity, Risk Zones, and Hazard Mapping
摘要
The paper presents a probabilistic assessment of seismic hazards for the Itanagar region of Arunachal Pradesh, India. In this study, earthquake data is compiled from the United States Geological Survey (USGS) around Itanagar in a circular enclosure of 500 km radius. The catalogue is homogenized into a unified scale of moment magnitude. The earthquake data is collected between 1900 and 2024. The Seismotectonic Atlas (SEISAT) provided fault information, which is combined with earthquake information to facilitate detailed analysis and visualization using ArcGIS software. There are 33 active tectonic features in the study area, of which 18 are found to be potential sources of seismic activity. The Gutenberg–Richter (G–R) relationship is used to determine the seismicity parameters for each source zone. The region is divided into four primary subzones based on seismic activity and tectonic characteristics. Based on linear sources identified within and around the study area, this study estimates the seismic hazard of the region. Based on the Probabilistic Seismic Hazard Analysis (PSHA) method, peak ground acceleration (PGA) values indicate a 2% probability of exceeding 0.22 g and a 10% probability of exceeding 0.36 g over 50 years. A spectral acceleration (Sa) is also assessed for return intervals of 475 years and 2475 years, across 0.1 s 0.3 s, 0.5 s, 1.0 s, 2.0 s, and 3.0 s. The findings from the study are compared with the with other localities in the Northeast region, as well as with specifications outlined in the IS 1893-Part-1 (2016). The results of this study can be used to develop risk reduction strategies, risk acceptance criteria, and financial analyses based on the results of the comprehensive analysis and higher resolution hazard mapping.