WATCH: The African lake that could explode with deadly gas
Tuesday, March 22, 2016, 1:41 PM - When you're by the lakeside, you might enjoy the sound of the waves, or the tranquility of the water, or perhaps how polluted it might be.
For people living alongside Africa's Lake Kivu, you can add a potential explosion of deadly gas to the mix.
The lake's waters, shared between Rwanda and the Democratic Republic of Congo, are infused with methane and carbon dioxide thanks to the area's volcanic activity. The methane alone accounts for about 60 million cubic metres and, like carbon dioxide, is deadly to humans in large quantities.
Rwanda, at least, is turning that giant reservoir of gas into energy, with a growing methane extraction industry funnelling the stuff into power plants. The Guardian reported in 2010 that the gas accounted for four per cent of Rwanda's power production that year, with plenty of room to grow.
Still, the presence of the gas is tremendously dangerous. While most of it is concentrated in the lake's lower depths, a strong event like an earthquake could bring it bubbling explosively to the surface, like fizz in a shaken pop bottle.
That deadly cloud of methane and carbon dioxide would be devastating to the two million people that live on the lake shore, potentially killing thousands of residents.
How do we know that's a risk? Because that kind of catastrophe, known as a limnic eruption, has happened before, in Lake Nyos in the West African nation of Cameroon.
Back in 1986, an as yet unclear event agitated the waters of the lake enough to cause the gas to explode outward, sending water hundreds of metres into the air and triggering a small tsunami.
But more dangerous was the cloud of carbon dioxide that wafted out, suffocating people nearby. More than 1,700 people were killed, along with around 3,500 livestock.