A massive earthquake that shook southern Asia 2,500 years ago suddenly changed the course of the Ganges River, new research shows. This earthquake was previously unknown to science, but researchers saw signs of its tremendous force in the terrain near Dhaka, the capital of Bangladesh. The team revealed its findings in a study published Monday (June 17) in the journal Nature Communications. The earthquake’s magnitude was probably 7.5 or 8 and was so powerful that it changed the direction of the main stream of the Ganga. Even though the displaced portion of the river was more than 110 miles (180 kilometers) from the epicenter of the earthquake.

The world has never changed like this

Rapid changes in the course of a river are called avulsions. Researchers have documented upwelling caused by seismic activity before, but “I don’t think we’ve ever seen upwelling of this magnitude,” Michael Steckler, a geophysicist and research professor at Columbia Climate School’s Lamont-Doherty Earth Observatory in New York, said in a statement. Ganga is one of the largest rivers in the world.

The Ganges is one of the world’s largest rivers, flowing for approximately 1,600 miles (2,500 km). It begins in the Himalayas on the border of India and China and then flows east through India to Bangladesh, where it joins other major rivers including the Brahmaputra and Meghna. The combined waterways expand to form the largest river delta on Earth and drain into the Bay of Bengal.