Why the recent 6.4 magnitude earthquake should be a wake-up jolt for Assam Scientists point that anthropogenic factors could contribute to earthquake triggers, although of smaller magnitude. 3 hours ago Seismic activity has a role to play in adding sediment load to the Brahmaputra river. | Vinoyblog/Wikimedia Commons When a strong, 6.4 magnitude earthquake shook Assam on April 28, there was panic and mayhem. The earth cracked near the epicentre in the Sonitpur district, and so did walls and ceilings of people’s houses scores of miles in the radius; buildings swayed “like betel nut trees in the wind”, a hill broke down, and water seeped out of paddy fields.