Spatio Temporal Analysis of Earthquake Potential in the Indo-Eurasian Collision Zone: Identifying Future Seismic Hotspots Using the Earthquake Susceptibility Index

The region near the India-Eurasia plate boundary has a long history of large earthquakes. Over the past century, more than 50 earthquakes with magnitudes of 7 or greater have occurred within 500 km of the Indo-Eurasian collision zone. These include the 2015 M7.8 Nepal earthquake, the 1934 M8.0 Bihar-Nepal earthquake, the 1950 M8.6 Assam earthquake, and the 1905 M7.9 Kangra earthquake. The January 7, 2025, M7.1 earthquake in the southern Tibetan Plateau further underscores the seismic significance of this region. This study examines the temporal variation in seismicity within the Indo-Eurasian collision zone and its adjacent areas by utilizing historical records and instrumentally recorded earthquake data from 1900 to 2024. Based on seismic behaviour, clustering of events, and tectonic structures, the collision zone is divided into 26 distinct seismic zones. The temporal variation in seismicity for each zone is analyzed, and a susceptibility index, ESI₆, is calculated. This index considers the return period of earthquakes with Mw ≥ 6 and the time elapsed since the last Mw ≥ 6 earthquake in each zone. The ESI₆ represents the number of pending Mw ≥ 6 earthquakes in each seismic zone. Ten zones with high ESI₆ values (>2.5) have been identified; these zones were seismically active in the past but have remained without major earthquakes for the last three decades. To mitigate potential losses and raise awareness, it is critical to implement GPS monitoring of plate movements, satellite-based deformation monitoring, and seismic health assessments of crucial infrastructure in these silent zones.