Science Behind the Cause of Earthquake in Nepal

Before knowing the Causes of Earthquake in Nepal, we need to know about the geological formation of Nepal. Nepal is a country which does not sit on single tectonic plate. It sits on the boundaries of two tectonic plates i.e. Indian plate and Eurasian plate ( also called Tibetan plate ). The Indian plate in south and the Eurasian plate in north started to collide millions of years ago after vanishing of Tethys sea in between them. The collision process is still active and this collision gave birth to Himalayas of which Nepal is the most important part. The collision process continued over years and some major and minor faults were developed within the area of our country. The study has shown the major three faults which are as below:

1. Main Frontal Thrust (MFT) / Himalayan Frontal thrust (HFT)
2. Main Boundary Thrust (MBT)
3. Main Central Thrust (MCT)

These faults have covered whole length of Nepal extending from east to west as shown in figure above. MFT separates Siwalik from Terai. MBT is the boundary between Siwalik and Lesser Himalaya where as MCT separates Lesser Himalaya and Higher Himalaya. The development of such weak zones will continue and are prone to earthquake.

The Indian plate is moving north at around 45 mm per year and pushing under the Eurasian plate due to which the rocks at the plate boundary are continuously undergoing deformation. During the deformation of plate great amount of stress is developed on the rock. Initially, the stress developed is resisted by frictional resistance. But when the stress exceeds the frictional resistance, the plates move along the fault plane releasing the accumulated energy due to which earthquake occurs.

I hope you have understood the idea of geological division and cause of earthquake in Nepal.