বাংলা 
English 
Many researchers and geologists believe that on 2 April 1762 a severe earthquake occurred in the south-eastern Bay of Bengal area, which caused great changes to the land in Chittagong and the coastal areas of Bangladesh.
The most powerful earthquake in the history of Bangladesh was the earthquake of magnitude 8.5-8.8 felt in 1762, as a result of which the course of the Brahmaputra changed and the Jamuna river was born. The strongest within Bangladesh was the Sreemangal earthquake of 1918, whose magnitude was 7.6. At present, as the tendency of earthquakes has increased in Bangladesh and its surrounding areas, experts fear a major earthquake at any time.
The earthquake of 2 April 1762 was one of the most mysterious and important seismic events in the history of the subcontinent. Its place of origin was at the bottom of the Bay of Bengal, mainly in the area between the Arakan coast and Chittagong, and it caused massive geographical and natural changes. Below is a detailed explanation of the notable changes that occurred to rivers, land and roads as a result of this earthquake:
The 1762 Earthquake: Changes to Chittagong's Rivers, Land and Natural Features
Epicentre of the earthquake:
- In the Arakan subduction zone north of the Andaman Sea.
- A part of the Bay of Bengal between the south-eastern coast of Chittagong and the then kingdom of Arakan was its main place of origin.
1. Tsunami and Tidal Surge:
Along with the earthquake a huge tsunami arose, which struck Chittagong, Cox's Bazar, Sandwip and the other coastal areas.
Several historical accounts mention that the seawater suddenly receded for a few hours and later the coast was flooded by terrible waves.
2. Land Uplift and Subsidence:
In the coastal areas of Chittagong the land rose by as much as 1.5 to 3 metres. As a result:
- Some rivers and canals dried up or changed course.
- Much new land emerged from the sea. Experts believe that this earthquake may have played a role in the formation of St Martin's Island.
Again in some places the land subsided and sank downward, as news of landslides was received in the hilly parts of the Teknaf or Naikhongchhari areas.
3. Damage to Roads and Land Routes:
At that time the roads were mainly made of earth or brick. Many roads cracked or sank completely and became unfit for travel.
On the road system from Chittagong to Arakan and into the interior Mughal routes, communication remained cut off for a long time because of landslides and cracks in various parts.
4. Change in the Courses of Rivers:
As a result of the earthquake and the tsunami the rivers created new flows. In particular:
- The Karnaphuli river changed its course in some parts.
- In many places the coastal canals and tributary rivers silted up and their flow stopped, while elsewhere the water rose and new rivers or wetlands were created.
- Signs of a change in the course of the Sangu and Matamuhuri rivers are also found in history.
5. Ports and Waterways:
- Chittagong port at that time was directly damaged.
- Shipping routes had to be changed because the waterways of the coast changed and many new chars (sandbars) were created.
6. Condition of the Town and Settlements:
- Many parts of the old quarters of Chittagong town (such as Badar Mokam, Andarkilla) and of the Mughal structures collapsed.
- Many mosques, forts and citadels were destroyed or partially sank.
- Thousands of people became homeless and a wave of migration swept the Chittagong and Cox's Bazar areas.
Historical References:
Some early reports of the British East India Company mention this earthquake, although at that time they had not yet come under full control.
Later the long-term geological impact of this earthquake was preserved in Bengali, English and Burmese documents.
In Modern Research:
The Geological Survey of Bangladesh and international research show:
- The earthquake was of the "thrust faulting" type that occurred in the subduction zone, as a result of which large vertical changes took place on the earth's surface.
- The present height of some coastal areas has changed permanently after this earthquake.
The earthquake of 1762 was not merely a natural disaster; rather it changed the geological nature, river system and pattern of settlement of Bangladesh's coastal areas. The imprint of this change still exists in Chittagong's geographical formation.
