Catastrophic Threat: Major Earthquake Could Reroute Ganges River Again, Study Reveals

Study Reveals Major Earthquake Could Reroute Ganges River Again
The team, led by Elizabeth Chamberlain (center), collects mud from the ancient Ganges River channel optically stimulated luminescence dating to analyze it Image: Mahfuzur Rahman
  • A study in Nature Communications reveals that a high-magnitude earthquake 2,500 years ago rerouted the Ganges River by 100 kilometers, highlighting the region’s vulnerability to seismic activity.
  • Bangladesh, near an active tectonic plate boundary, faces ongoing risks of future earthquakes potentially rerouting the Ganges again, posing catastrophic displacement and economic disruption.
  • The findings underscore the need for global hazard planning and preparedness for regions near seismic zones, emphasizing the importance of understanding and mitigating such natural threats.

A groundbreaking study has revealed that a major earthquake, similar to one that occurred 2,500 years ago, could potentially reroute the Ganges River, one of the largest rivers on Earth, altering the landscape of Bangladesh dramatically.

This finding underscores the vulnerability of the region to seismic activity and highlights the potential catastrophic impact on one of the most densely populated areas on the planet.

Historical Earthquake and Rerouting of the Ganges

The study, published in the journal Nature Communications, provides the first evidence of a large river delta being completely relocated by an earthquake.

According to lead author Elizabeth Chamberlain of Wageningen University in the Netherlands, a high-magnitude earthquake 2,500 years ago rerouted the main channel of the Ganges River, creating a significant shift in the surrounding landscape.

While it is normal for river channels to move with time, this was an absolutely extreme event. The river moved to an entirely new area,” Chamberlain explained.

The earthquake, estimated to be between magnitude 7 and 8, caused the river to divert its course by approximately 100 kilometers, fundamentally reshaping the region.

Potential for Future Earthquakes

Bangladesh, situated near an active tectonic plate boundary, is particularly susceptible to major earthquakes.

Christoph von Hagke of the University of Salzburg, Austria, who contributed to the study, noted that the Ganges-Brahmaputra river system has shifted multiple times over the past 6,000 years due to seismic activity.

The researchers used satellite imagery and chemical analysis of sediments to identify the historical rerouting event and assess the potential for future occurrences.

This proximity brings frequent major earthquakes,” said Till Hanebuth, a geosciences specialist at Coastal Carolina University in the US, who was not involved in the study.

Hanebuth emphasized the ongoing risk, pointing out that while the region is not currently considered at high risk, another high-magnitude earthquake could cause the Ganges to relocate again within the next few hundred to a thousand years.

Implications for Bangladesh

The possibility of another earthquake rerouting the Ganges River has profound implications for Bangladesh, which hosts one of the world’s most densely populated landscapes.

Such an event would be catastrophic, displacing millions of people and disrupting agricultural and economic activities.

It was indeed a very extreme event — in fact, two extreme events occurred. An earthquake of magnitude 7 to 8 is already extreme, but it caused redirection [known as avulsion] of the main channel of the Ganges,” von Hagke explained.

“A new event of the same size would be catastrophic for the region because it would hit a super densely populated region.”

Other Factors Influencing Ganges River Relocation

While earthquakes are a significant factor in river rerouting, they are not the only cause. Extreme weather events, such as major monsoons or cyclones, as well as human-made factors like the collapse of major river dams, can also lead to abrupt river avulsions.

Hanebuth pointed out that these events, whether natural or human-induced, could have similar devastating effects on river systems.

Challenges in Predicting Earthquakes

Predicting earthquakes and their potential impact on river systems remains a challenge. Scientists cannot pinpoint the exact timing or magnitude of such events, making it difficult to prepare for them adequately.

For different earthquake scenarios, one could estimate landscape changes and then possible effects on rivers and water masses. But we cannot pinpoint the timing of an event that only happens every few hundred to a few thousand years,” von Hagke said.

However, the study’s findings offer valuable insights for hazard planning and mitigation. Understanding that high-magnitude earthquakes can completely reroute rivers allows researchers to better predict and prepare for the potential impacts of such events.

“We hope this knowledge can be helpful for hazard planning and mitigation before a modern event,” Chamberlain said.

Global Perspective

The Ganges is not the only river facing the risk of earthquake-related hazards. Other rivers, including China’s Yellow River, Myanmar’s Irrawaddy, the Klamath, San Joaquin, and Santa Clara rivers on the US West Coast, and the Jordan River, which spans Syria, Jordan, the Palestinian West Bank, and Israel, also lie near active seismic zones.

These findings underscore the need for global awareness and preparedness for the potential impacts of major seismic events on river systems.

As the threat of major earthquakes looms over regions with large river systems, the need for comprehensive hazard planning and mitigation strategies becomes increasingly urgent.

The study’s revelation that a high-magnitude earthquake could once again reroute the Ganges River serves as a stark reminder of the power of natural forces and the importance of preparedness in the face of such potentially catastrophic events.

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