In 1986, possibly as the result of a landslide, Lake Nyos suddenly emitted a large cloud of CO2, which suffocated 1,700 people and 3,500 livestock in nearby towns and villages. Though not completely unprecedented, it was the first known large-scale asphyxiation caused by a natural event.
12 years later, precisely on 14th February 1998, another incident occurred in Nsam Efoulan in Yaounde, when a train making its maneuver saw its full fuel wagons came off to go bumping another wagon.
The wagons that fell, then let out the fuel they carried. For nearly four hours, people coming from around the accident site and even elsewhere, refuel without worrying about the danger. The irreparable happened when fire was invited to the party, transforming the place into a gigantic blaze fed by over 100 000 liters of gasoline. At the end, we had nearly 200 victims, and many burned scattered across different health centers.
Nine years later, Kenya Airways Flight 507 was a scheduled Abidjan–Douala–Nairobi passenger service, operated with a Boeing 737-800, that crashed in the initial stage of its second leg on 5 May 2007, immediately after takeoff from Douala International Airport in Cameroon.
The plane broke up into small pieces and came to rest mostly submerged in a mangrove swamp, 5.4 kilometres (3.4 mi) to the south (176°) of the end of the Douala International Airport’s runway 12. There were no survivors. The investigation by the Cameroon Civil Aviation Authority determined that the pilots failed to notice and correct excessive bank following takeoff. This led to the loss of control and crash of the aircraft.
After the crash, the flight route designation was changed from KQ507 to KQ504 for flights between Douala and Nairobi with the same aircraft type. It made a total of 114 victims.
Nine years later, that is on the 21 October 2016, the Train accident of Eseka occurred, although official figures mention over 70 dead, some people claim it’s more than that.
We can notice that the dates are respectively 1986, 1998, 2007, and 2016, and average of roughly 10 years gap for each major incident in Cameroon. So one can be tempted to predict another incident around 2025.