For the past week, ever since Campi Flegrei was awarded third place in the New Decade Volcano Program, I’ve wondered which volcanoes could possibly present a greater threat. Nothing that comes to mind meets the criteria. The Auckland volcanic field lies directly under the New Zealand city and could erupt at any time, but the magma involved is basaltic and not explosive; other north island volcanoes probably present a greater danger to the inhabitants than the one directly below them. There are plenty of dangerous mountains in Iceland, but the the total population is less than that of Wichita. Kamchatka is also sparsely populated. Islands in the South Pacific are generally too small to support millions of residents. And so on.
While reading the most recent post at Volcano Café, on how vulcanism affected the waters of Lake Tanganyika, it occurred to me that maybe I’m thinking too literally. Perhaps I should look for placid lakes, not fiery mountains. Lake Kivu, for instance.
In 1984, Lake Monoun in Cameroon experienced a “limnic eruption,” releasing an asphyxiating cloud of carbon dioxide that killed 37 people. Two years later at Lake Nyos, also in Cameroon, a similar event suffocated 1,700 more. Both lakes are “meromictic,” in which the water remains stratified throughout the year.
Lake Kivu is another meromictic lake, and its depths are saturated with carbon dioxide. It’s also 2,000 times larger than Lake Nyos, and there are over two million people along its shores. Nearby is Mount Nyiragongo, noted for its lava lake and its very fluid lava that could readily travel to the lake and trigger a limnic eruption. There is evidence that these eruptions occur there regularly. From Wikipedia:
Sample sediments from the lake were taken by professor Robert Hecky from the University of Michigan, which showed that an event caused living creatures in the lake to go extinct approximately every thousand years, and caused nearby vegetation to be swept back into the lake.
So, I am going to guess that the Lake Kivu/Nyiragongo complex is one of the two remaining NDVP volcanoes. We’ll find out if I’m right in one or three weeks if the café maintains its schedule.