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The University Magazine

Rwandan lake contains potential for catastrophe

Anthony Vodacek


Lake Kivu, on the western border of Rwanda, could pose a threat to millions of people residing nearby.

A sleeping giant rests at the bottom of Lake Kivu bordering Rwanda and the Republic of Congo. Scientists can’t say for sure if it will slumber for another 1,000 years or someday explode without warning.

A dangerous level of carbon dioxide and methane gas haunts the freshwater lake system in a region prone to volcanic and seismic activity. Compounding the precarious situation is the presence of approximately 2 million people, many of them refugees, living along the north end of the lake.

Anthony Vodacek, associate professor at RIT’s Chester F. Carlson Center for Imaging Science, worked closely with the Rwandan Ministry of Education to organize a January meeting of international researchers interested in this situation.

“Rwandan universities suffered greatly in the 1994 genocide and there are few Rwandan scientists performing significant work on the lake or within the rift system,” he notes.

Vodacek is working with Cindy Ebinger, an expert in East African Rift tectonics at the University of Rochester, and Robert Hecky, an expert in limnology – the study of lake systems – at University of Minnesota-Duluth. Core samples Hecky took in the 1970s initially brought the safety of Lake Kivu under question.

“Most scientists are fairly in agreement that the lake is pretty stable; it’s not as if its going to come bursting out tomorrow,” Vodacek says. “But in such a tectonically and volcanically active area, you can’t tell what’s going to happen.”

One of the problems is that the 1,600-foot-deep lake never breathes. The tropical climate helps stagnate the layers of the lake, which never mix or turn over. In contrast, fluctuating temperatures in colder climates help circulate lake water and prevent gas build up.

Close calls occurred in 2008 when an earthquake occurred near the lake and in 2002 when a volcanic eruption destroyed parts of Goma in the Democratic Republic of Congo, only 11 miles north of Lake Kivu.

Vodacek likens the contained pressure in the lake to a bottle of carbonated soda or champagne. “In the lake, you have the carbon dioxide on the bottom and 300 meters of water on top of that, which is the cap,” he says. “That’s the pressure that holds it. The gas is dissolved in water.”

When the cap is removed, bubbles form and rise to the surface. More bubbles form and create a column that drags the water and the gas up to the surface in a chain reaction.

“The question is, and what’s really unknown, is how explosive is that?” Vodacek says.

Through his own research, Vodacek plans to simulate the circulation of Lake Kivu. Modeling the circulation patterns above the layers of carbon dioxide and methane will help determine the energy required to disrupt the gas and cause Lake Kivu to explode.

Susan Gawlowicz 95