GANGES
: GEOGRAPHY
NEWS: Earthquake 2,500 years ago abruptly changed
Ganga river’s course
WHAT’S
IN THE NEWS?
Discovery
of Ancient River Avulsion:
- The Ganga River changed
course 2,500 years ago, identified through an ancient paleochannel and two
large sand dikes in the Ganges delta, Bangladesh.
River Avulsion:
- River avulsion is the sudden shifting of a
river’s course, often due to natural events like earthquakes or flooding,
altering river systems and sediment deposition.
Evidence
of Earthquake-Induced Avulsion:
- Sand dikes formed by liquefaction during an
earthquake provided evidence of a major quake coinciding with the river
avulsion.
- Optically Stimulated Luminescence (OSL) dating
confirmed both events occurred simultaneously.
Optically
Stimulated Luminescence (OSL) Dating:
- OSL dating measures trapped electrons in
mineral grains to determine the time since they were last exposed to
sunlight or heat, useful for dating sediments.
Implications
for Earthquake and River Dynamics:
- Large earthquakes can cause significant river
avulsions, leading to severe flooding, especially in densely populated
regions like the Ganges-Meghna-Brahmaputra delta.
Future
Risks and Considerations:
- Earthquake-induced avulsions are compounded by
factors like rapid subsidence, embankments, rising sea levels, and extreme
weather events due to climate change.
- Increased research is needed to understand
quake-driven avulsions and develop forecasting methods.
Preparation
and Coordination:
- Effective risk management requires
collaboration among India, Bangladesh, and Myanmar for research,
monitoring, and preparedness to mitigate future impacts on vulnerable
regions.
Source
: https://epaper.thehindu.com/ccidist-ws/th/th_delhi/issues/94122/OPS/GJCD5NRA8.1+GK7D5NRRK.1.html