Earthquake 2,500 years ago abruptly changed Ganga river’s course

• Based on geological measures in the Ganga river area, researchers found the Ganga had abruptly changed its course or avulsed about 2,500 years ago, leaving behind the palaeochannel.
• Paleochannel is a well-preserved mud and sand archive of the river’s ancient course about 45 km to the south of the modern Ganga river.
• Today, the area is used to cultivate rice.

Study findings

• During their fieldwork, the team also chanced upon two large sand dikes a kilometre to the east of the palaeochannel.
• These dikes are formed when earthquakes disturb the river bed and cause sediments to flow as if they were liquid.
  • Scientists call this process liquefaction.
• The study’s findings call for urgent forecasting of major earthquakes that can cause avulsion of rivers like the Ganges

Future hazards

• This discovery that large earthquakes can potentially trigger major river avulsions suggests that the impact of large earthquakes can be even more devastating than previously thought
• Avulsions have caused some of the deadliest floods in human history, and the cascading impacts of earthquakes and flooding can be severe for heavily populated regions like the Ganges-Meghna-Brahmaputra delta.
• The risk is exacerbated by human activities and climate change,
• Future research should focus efforts to find out how often such quake-driven avulsions have happened and how such major earthquakes can be forecast.