| Avulsion is the natural process by which flow diverts out of an established river channel into a new permanent course on the adjacent floodplain. |
- In 2018, a geochronologist team from the Netherlands studied the movement of river channels in the Ganges. A finding published in June 2024 in Nature Communications, showed a magnitude 7-8 earthquake caused the Ganga’s course shift.
- They discovered a 2-km-wide paleochannel, indicating the Ganga abruptly changed its course about 2,500 years ago, leaving this ancient river path.
- This area, now used for rice cultivation, revealed sand dikes formed by earthquakes, providing the first proof that earthquakes can move rivers.
- The research used optically stimulated luminescence (OSL) dating to determine the timing of the earthquake and avulsion, confirming both events occurred around 2,500 years ago.
- The earthquake likely originated in the Indo-Burma mountain ranges or the Shillong hills, both tectonic plate boundaries.
- This discovery suggests that large earthquakes can trigger major river avulsions, potentially causing devastating floods, especially in heavily populated regions like the Ganges-Meghna-Brahmaputra delta, home to 630 million people.
Dig Deeper: List Himalayan Rivers which are subject to frequent course changes.
