Spatiotemporal Patterns of Earthquake Occurrence and Their Relationship to Hydrological Parameters in the Delhi-NCR.

Irrespective of the tectonic setting hydrological factors play an important role in influencing earthquake activity of region. This study investigates the influence of hydrological factors on earthquake occurrence in the Delhi-NCR region using satellite-based data from GRACE, GRACE-FO, CHIRPS, and GNSS. Analysis reveals a significant decline in groundwater levels despite relatively stable rainfall, indicating substantial anthropogenic groundwater extraction. The spatial analysis reveals a correlation between earthquakes and regions with higher rainfall and groundwater levels, primarily in the northern part of the Delhi-NCR region, which is closer to the Himalayas. Where less rainfall and low groundwater levels in the region lead to sporadic earthquakes, particularly in the southern part of Delhi NCR, where the Delhi supergroup rocks are exposed. Temporal analysis, however, reveals subtle relationships. In the northern region of Delhi-NCR, which is closer to the Himalayan region, earthquakes tend to follow periods of post-monsoonal elevated groundwater unloading, while in the southern region, with greater rock exposure, seismic activity correlates more strongly with rainfall patterns. These findings highlight the importance of considering hydrological factors, particularly anthropogenic impacts on groundwater resources, in seismic hazard assessments for the Delhi-NCR region.

Keywords: Groundwater, Rainfall, Earthquake, Unloading.