Lake Kivu is seen turning a light shade of blue in this image captured from space on April 20, 2016.

(Image via NASA)

Considered one of Africa's Great Lakes, Lake Kivu is an important waterway for shipping, fishing and providing drinkable water on the border between Rwanda and the Democratic Republic of Congo. When a recent, sudden color change occurred with the lake's water, residents and experts immediately took note.

As documented by NASA's Terra and Aqua satellites from April 10-20, Lake Kivu went from a deep shade of blue to almost entirely a lighter shade of blue, known as whiting, NASA said.

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Over a 10-day span, here's how much the lake's water changed, in terms of color:

(Images via NASA)

Any change in this lake affects two million people, so experts have zeroed in on Kivu to learn more about what caused the color change. The lake sits atop the continent's longest volcanic rift, according to the Huffington Post, and its waters "are supersaturated with potentially volatile gases that could one day explode violently and kill thousands."

Those gases include carbon dioxide, which is slowly building toward a major explosion under the lake. If the gas builds to an extreme level, The Weather Network said, it could come shooting out of the lake in a huge eruption.

Why do people live in an area facing such a risk? Aside from the gorgeous scenes, the land around Lake Kivu is extremely fertile, Pacific Standard said, and the fish caught in the waterway are sold in large amounts as food. The methane gas inside the lake could also theoretically be used as a source of energy in the country where only 20 percent of citizens have electricity, the report added.

There's no proof that the recent whiting event is a sign that catastrophe is imminent, but scientists are investigating the phenomenon just to be safe.

“We don’t yet know for sure what caused this particular whiting event at Lake Kivu,” Martin Schmid of the Swiss Federal Institute of Aquatic Science and Technology told NASA. “It is certainly unusually strong, but there have been similar weaker events before. It can be caused by a phytoplankton bloom, by high surface water temperatures, or by a combination of both.”

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