Evaluation of Seismic Hazard for Northeastern Bihar (India): A Deterministic Approach

This study focuses on a deterministic map of seismic hazards for Kishanganj district considering worst-case scenario ground acceleration response during earthquakes. An international border with Nepal separates Kishanganj from the Indian state of Bihar. The district has experienced multiple historical earthquakes, such as those that affected Nepal in 2015 and India in 1934. Hence, it is essential to quantitatively assess Kishanganj’s seismic hazard to augment the earthquake preparedness efforts in the region. A comprehensive homogenized earthquake catalog, consisting of the events that happened in the past 400 years with 500 km in all directions from Kishanganj, was assembled. In estimating hazard values, we used a logic tree method that uses four ground motion prediction equations. The peak ground accelerations (PGAs) were found to vary between 0.25 and 0.37 g in the studied area. The hazard map was dissected into four regions, with north to south likely experiencing progressively stronger ground motions. The southern region, which includes the main urban center of Kishanganj and Kochadhamin, along with parts of the eastern area like Pothia, shows higher peak ground accelerations (PGAs) ranging from 0.30 to 0.37 g. These locations are considered more susceptible to seismic hazards. In contrast, the northern and central regions, including Terhagachh, Dighbank, and Thakurganj blocks, demonstrate lower PGAs and are therefore less vulnerable. The results of this study may be considered as an added factor of safety in town planning and land use planning, and encourage the district’s most susceptible region to have structures designed to withstand earthquakes.