A series of earthquake hit Assam in the early hours of April 28. The first earthquake which occurred at 7.51 AM was the strongest one measuring 6.4 on the Richter scale. The National Centre for Seismology marked the epicentre 43 km west of Tezpur and at a depth of 17 kilometres. After the first tremors, 6 mild aftershocks were also felt in the region. The tremors were felt in other parts of the northeast, Bengal, Bhutan and Bangladesh. No casualties were reported, but many buildings were severely damaged. The Indo-Gangetic plain and the Siwalik Himalaya are two of the most seismically active regions in the world. This is due to their proximity to the Himalayan seismic zone, where the Indian and the Eurasian continental plates collide with each other. This entire region can witness very large earthquakes of over 8.5 on the Richter scale. The impact of these earthquakes will be devastating as more than 500 million people live here.