A recent study reveals that a massive earthquake 2,500 years ago caused the River Ganga to change its course abruptly. This significant discovery highlights how seismic activities can influence river paths, a phenomenon known as avulsions. While rivers are known to alter courses over time, this study is the first to link such a change in the Ganges to an earthquake.

Massive earthquake
Image Source: Environmental News Network

The Ganga, which currently flows over 2,575 kilometres (1,600 miles) from the Himalayas to the Bay of Bengal, forms the world’s second-largest river system. The idea that such a massive water body could shift due to an earthquake seems extraordinary, but the study shows that these changes can happen almost instantaneously.

Seismites: Evidence of a Massive Earthquake

The research team used satellite imagery to identify a former main channel of the Ganga running parallel to its current path for about 100 kilometers (62 miles). During an exploration in 2018, they discovered sand volcanoes, or seismites, along the old riverbed. Seismites are vertical strips of sand formed by earthquakes.

Chemical analysis of these seismites indicated they were created around 2,500 years ago. Researchers believe a magnitude 7 or 8 earthquake at that time reshaped the landscape, causing the Ganges to shift its course.

The source of this earthquake could have been a subduction zone where part of the oceanic crust is moving under Bangladesh, Myanmar, and northeastern India. Additionally, large faults at the base of the Himalayas might have contributed to this significant seismic event. This finding raises concerns as these zones could potentially experience similar earthquakes in the future.

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