Impact of Climate Change and Terrestrial Water Storage on the Himalayan Seismicity

The Himalayan terrain epitomises continuing convergence and geodetic deformation caused by tectonic and non-tectonic factors. Climate change and induced secondary factors are some of the dominant non-tectonic forces. A small change in stress and pore-fluid pressure caused by precipitation and temperature fluctuations may trigger seismic activity in the vicinity of already critically stressed faults and fractures at local and regional scales. The increase in temperature has also resulted in the melting of mountain glaciers in the Himalayan region and the release of the glacial load, leading to post-glacial rebound and elastic deformation. This study investigates the correlation and causal relationship between climatic parameters and earthquakes in the Himalayas. Further, we study the hydrological loading effect (derived from the GRACE/GRACE-FO satellite) and correlate it with the seismic hazard map. The results show that temperature anomalies have a relatively strong influence (r ~0.36-0.54) on the occurrence of minor-magnitude earthquakes in the Eastern Himalayas. However, the North-western Himalayas show a moderately positive correlation with precipitation anomalies (r ~0.23-0.37). Furthermore, a positive correlation has been found between regional terrestrial water storage (TWS) influence and the seismic hazard, ranging from 0.04-0.45. The result shows higher positive correlation values in the post-monsoon period for the North-western and Eastern Himalayas, whereas the Central Seismic Gap and Eastern Nepal and Sikkim show a higher value for the pre-monsoon period.