Bay of Bengal’s cyclone has a real bad image and It’s really hard to imagine several hundred thousand people losing their lives from a single tropical cyclone, but in November 1970, that is exactly what happened. (Note: A tropical cyclone is what we refer to as a hurricane in the Atlantic Ocean.)
As a result, at least 300,000 people in the low-lying region near the Bangladesh coast were killed by massive flooding from the powerful cyclone. The actual number of people killed varies by source and could be as high as 500,000. Using either figure, this is the deadliest known tropical cyclone in history.
Over 45 percent of the population of 167,000 in the city of Tazumuddin was killed, according to NOAA.
Sadly, this isn’t the only Bay of Bengal’s tropical cyclone that has resulted in a large death toll in Bangladesh. According to a publication from the Bangladesh Meteorological Department, a total of 10 tropical cyclones since 1876 have had death tolls of 5,000 or higher. Four of those cyclones killed 100,000 or more. Most recently, Cyclone Gorky killed nearly 140,000 in 1991.
Bangladesh isn’t the only country with a deadly history of tropical cyclones in the Bay of Bengal.
The northeast coast of India is also very prone to storm surge. This list from Weather Underground shows that India has seen several tropical cyclones originating in the Bay of Bengal that resulted in some extremely high death tolls.
For perspective, the deadliest hurricane in U.S. history was the 1900 Galveston hurricane, which killed an estimated 8,000 people. Hurricane Katrina, the third deadliest hurricane in U.S. history, was directly responsible for 1,200 fatalities
Several factors make the Bangladesh coast and portions of the Myanmar and India coasts very vulnerable to storm surge.
First, these areas with the high death tolls are very low in elevation and have high populations because of agriculture in the region. This puts many people at risk if they do not follow warnings to protect themselves or if sufficient shelter is not available.
Second, The northern end of the Bay of Bengal is very shallow and narrows. This creates a funnel for the huge surge from strong tropical cyclones moving north or northeast into the low-lying land areas.
Third, Very high astronomical tides add significantly to the height of the surge if the cyclone is making landfall during high tide.According to the Bangladesh Meteorological Department, this was the case in both the 1970 and 1991 cyclones mentioned on the previous page,
Fourth, Areas along the coast have many small inlets that water is forced into by landfalling tropical cyclones, which causes flooding of adjacent land areas.