Just Richter 5 or greater earthquakes in the last forty years. One might think that most of these earthquakes are too far away and too weak to disrupt Lake Kivu. There are three problems: (1) the lake is already so saturated with methane and carbon dioxide that comparatively very little movement would be needed to trigger an overturn (2) earthquakes can trigger volcanic activity - the lake is within easy lava range of Nyiragongo - as well as slope failures along the western shores (3) As a Rift lake, Kivu is right on the Albertine fault where Africa is relentlessly being torn apart. Earthquakes here rarely follow a classical pattern.