A groundbreaking study has revealed that a major earthquake 2,500 years ago dramatically altered the course of one of the world’s largest rivers, the Ganges. This previously undocumented earthquake diverted the main channel of the Ganges in what is now Bangladesh, a region still susceptible to significant seismic activity. The study, recently published in the journal Nature Communications, sheds light on the potential for future catastrophic changes in river courses due to seismic events.
Historically, many river course changes, known as avulsions, have been documented, some of which were triggered by earthquakes. However, the scale of the Ganges avulsion is unprecedented. I don’t think we’ve ever seen one this large anywhere, said Michael Steckler, a geophysicist at the Lamont-Doherty Earth Observatory, part of Columbia University’s Climate School. Such an event could have easily inundated anyone or anything in the wrong place at the wrong time, Steckler noted.
Lead author Liz Chamberlain, an assistant professor at Wageningen University in the Netherlands, remarked, It had not been previously confirmed that earthquakes could cause avulsions in deltas, especially for a river as immense as the Ganges.
The Ganges originates in the Himalayas and flows approximately 2,600 kilometers, eventually merging with other major rivers, including the Brahmaputra and the Meghna. Together, these rivers form a complex network of waterways that empty into a broad expanse of the Bay of Bengal, spanning Bangladesh and India. This network constitutes the world’s second-largest river system by discharge, second only to the Amazon.
Like other rivers traversing large deltas, the Ganges periodically experiences course changes without the aid of earthquakes. Sediments carried downstream settle and accumulate in the river channel, eventually causing the riverbed to subtly rise above the surrounding floodplain. At some point, the water breaks through and begins carving a new path. But this usually doesn’t happen all at once; it can take successive floods over years or decades. An earthquake-related avulsion, on the other hand, can happen more or less instantly, Steckler explained.
Satellite imagery used by the researchers revealed what they believe to be the ancient main channel of the river, located about 100 kilometers south of Bangladesh’s capital, Dhaka. This low-lying area, approximately 1.5 kilometers wide, extends intermittently for about 100 kilometers, roughly parallel to the current river course. The area, filled with mud, frequently floods and is mainly used for rice cultivation.
In 2018, Chamberlain and other researchers discovered distinctive vertical dikes of light-colored sand cutting through horizontal layers of mud in a freshly dug pond. This feature, known to be created by earthquakes, results from sustained shaking that pressurizes buried sand layers, causing them to inject upwards through the overlying mud, forming sand volcanoes, or seismites. These seismites were found to be 30 to 40 centimeters wide, cutting through 3 to 4 meters of mud.
Further investigation showed that these seismites were oriented systematically, indicating they were created simultaneously. Chemical analyses of the sand grains and mud particles revealed that the eruptions and the abandonment and filling of the channel occurred about 2,500 years ago. Additionally, a similar site 85 kilometers downstream in the old channel filled with mud at the same time. The authors concluded that this was a sudden, large avulsion triggered by an earthquake estimated at magnitude 7 or 8.
The earthquake could have originated from one of two potential sources. One is a subduction zone to the south and east, where a massive oceanic crustal plate is pushing under Bangladesh, Myanmar, and northeastern India. Alternatively, it could have come from giant faults at the foot of the Himalayas to the north, which are rising due to the slow collision of the Indian subcontinent with the rest of Asia. A 2016 study led by Steckler indicates that these zones are currently accumulating stress and could produce earthquakes comparable to the one 2,500 years ago. The last such event occurred in 1762, generating a deadly tsunami that traveled upriver to Dhaka. Another might have occurred around 1140 AD.
The 2016 study estimates that a modern recurrence of such an earthquake could affect 140 million people. Large earthquakes impact extensive areas and can have lasting economic, social, and political effects, said Syed Humayun Akhter, vice-chancellor of Bangladesh Open University and co-author of both studies.
The Ganges is not the only river facing such risks. Other rivers in tectonically active deltas include China’s Yellow River, Myanmar’s Irrawaddy, the Klamath, San Joaquin, and Santa Clara rivers on the US West Coast, and the Jordan River, spanning the borders of Syria, Jordan, the Palestinian West Bank, and Israel.
SOURCES
Columbia Climate School / Columbia University
Chamberlain, E.L., Goodbred, S.L., Steckler, M.S. et al. Cascading hazards of a major Bengal basin earthquake and abrupt avulsion of the Ganges River. Nat Commun 15, 4975 (2024). doi.org/10.1038/s41467-024-47786-4
- Share on:
Discover more from LBV Magazine English Edition
Subscribe to get the latest posts sent to your email.
A heroon with intact tombs filled with luxurious jewels and lions sculpted in Pentelic marble, found in the ancient Greek city of Ripes in Achaea
At the beginning of October, the systematic archaeological excavation season concluded on the Trapezá plateau, located eight kilometers southwest of Aigio, Greece. This site is identified with the ancient city…
Statue Possibly Representing Cleopatra VII and Numerous Coins Featuring Her Effigy Found at the Temple of Taposiris Magna, West of Alexandria
The Egyptian-Dominican archaeological mission, led by Dr. Kathleen Martínez in collaboration with the National University Pedro Henríquez Ureña (UNPHU), has made new discoveries at the Temple of Taposiris Magna, located…
Roman Soldier Flaccus’ Tomb Discovered in the Netherlands, Dating to the Late 1st Century BCE
In late November 2024, during archaeological investigations conducted in Heerlen (Netherlands), an exceptional discovery was made: the tomb of a Roman soldier named Flaccus. This find, dating to the late…
The Mystery of the Mardaites: The Christian Highlanders Who Maintained Their Autonomy Between Byzantium and the Caliphate
In the province of Hatay, in southern Turkey, there is a mountain range locally known as Nur Dağları. Arabs call it Jabal al-Lukkam, and in Spanish, its Greek name, Amanus,…
The Jaxartes River, the Battle Where Alexander Defeated the Scythians Using Catapults, Wounded and with Nearly His Entire Army Sick with Dysentery
As its name indicates, the Spanish Cape of Finisterre (finis terrae) was considered in Antiquity as the westernmost limit of the known world. But where was the eastern border located…
Nature of the Enigmatic “Armas de la tierra” of the Coronado Expedition in the 16th Century Revealed
Recent research has unveiled the nature of the weaponry used by Francisco Vázquez de Coronado’s expedition (which crossed the present-day U.S. states of Arizona, New Mexico, Texas, Oklahoma and Kansas),…
A Megalography Depicting a Rare Mythological Scene of Achilles and Bronze Statuettes Found in a Roman “Domus” in Reims
The urban organization of Durocortorum, the Gallo-Roman city now known as Reims in France, faithfully adhered to the principles of Roman urbanism. The city was divided into blocks bounded by…
Neolithic Rondel Found in Poland Reveals These Ceremonial Centers May Have Been Managed by Organizations Similar to Secret Societies 7,000 Years Ago
An archaeological discovery in the locality of Nowe Objezierze, in the northwest of Poland, has led to a significant breakthrough in understanding the Neolithic societies of Central Europe. An interdisciplinary…
New Geoarchaeological Evidence Challenges the Identification of Kalkriese Hill as the place of the Battle of the Teutoburg Forest
Kalkriese Hill, located in northwestern Germany, has been identified for decades as a potential site of the historic Battle of the Teutoburg Forest in 9 CE, a decisive confrontation between…
The Newly Formed Earth Was a Dry and Hot Place: A Theory Explains How Water Arrived Here and on Other Planets of the Solar System
A group of scientists from the Paris Observatory has proposed a new theory about how water arrived on Earth, a key question for understanding the emergence of life on our…
Something went wrong. Please refresh the page and/or try again.
