Rwanda’s environmental agency said Monday that there was “no imminent risk” of Lake Kivu spewing lethal gases, a feared scenario after the eruption of a volcano in neighbouring DR Congo.
Mount Nyiragongo, which looms over the Congolese city of Goma, erupted on May 22, sending rivers of lava through homes and killing almost three dozen people.
Some 400,000 have evacuated the eastern city, which borders Rwanda, amid fears of a second eruption of Nyiragongo, or a “limnic eruption” from volcanic activity under Lake Kivu which straddles both countries.
One of Africa’s Great Lakes, the body of water contains large amounts of dissolved methane and carbon dioxide deep in its waters, and is one of three lakes susceptible to deadly expulsions of suffocating gas, along with Lakes Nyos and Monoun in Cameroon.
The Rwanda Environment Management Authority (REMA) said in a statement that its Lake Kivu monitoring team “has come up with a conclusion that there is no imminent risk of gas outburst expected in Lake Kivu” after the eruption.
“The team is confident with the results after different measurements and evaluation carried out on the Lake to assess the probable impact of the eruption on Lake Kivu. The lake continues to be stable as it has always been.”
The statement said that despite concerns as hundreds of aftershocks rattled the region, activating an existing fault leading to the shore of the lake, lava did not flow towards its potentially deadly waters.
The phenomenon of limnic eruption first came to the world’s attention in August 1984, when 37 people mysteriously died at Lake Monoun in western Cameroon.
Scientists found that dissolved carbon dioxide (CO2) gas in the depths of the lake had erupted, creating invisible clouds at the surface that were borne by winds into homes and fields, snuffing out life.
Two years later, more than 1,700 people and thousands of cattle died in Lake Nyos, also in Cameroon, strengthening the belief that earthquakes and volcanic activity can trigger these unusual events.
While potentially deadly, the dissolved methane is also a valuable resource, and Rwanda extracts it and uses it for energy production.
Six volcanoes dot the Goma region, dominated by Nyiragongo, which is 3,470 metres (11,400 feet) high, and Nyamuragira, at 3,058 metres.
Nyiragongo last erupted on January 17, 2002, killing more than 100 people and covering almost all of the eastern part of Goma with lava, including half of the airport’s landing strip.
Its deadliest eruption was in 1977, when more than 600 people died.
Aftershocks appeared to have subsided on Monday, and some of the thousands who fled across the border to Rwanda – where homes were destroyed by the earthquakes – had begun returning, an AFP correspondent said.