The sight of a lava lake overflowing is a rare phenomenon. But in January 2017 this happened in the Erta-Ale volcano in the Danakil desert of Ethiopia. Here the 1000 degree melt from the earth´s interior, rising and falling like in a pipe in the chimney of the mountain of fire, has overflowed. A kilometre-long lava stream poured into the large cauldron on top of Erta-Ale.
We had already visited the volcano about ten years back with a group of scientists doing research on the lava lake. This required special permission from the Ethiopian authorities. A military helicopter dropped us for a couple of days in this god-forsaken desert. Saada, a princess of the Afar tribe living there accompanied us with a group of soldiers to protect us from marauding bands.
The level of the quivering melt was just some tens of metres below the edge of the crater. In spite of the hardships it was one of the most spectacular trips we have ever undertaken.
The Erta-Ale volcano, unlike many other cone-shaped volcanoes, is very flat. Its long stretching summit collapsed in itself some time in the distant past, leading to the formation of a crater, a large cauldron which in the course of time filled up with lava again. In this caldera there are now two open holes, so-called pit craters. From one of these rise clouds of caustic sulphur. In the other smaller pit crater the lava lake boils away.
The black cooling skin with a temperature of only about 400° C lies like a blanket on the glowing mass bubbling below at over 1000° C. Where the skin bursts open lava fountains shoot up to heights of about 30 metres, bubble for a few minutes, then disappear.
This is caused by the gases dissolved in the glowing magma. These gases react like gas bubbles in a pot of boiling custard. They keep the lava lake in constant motion and repeatedly cause the glowing magma to penetrate and burst through.
When we were there the lake was roughly 80 metres below the crater rim, which was very fortunate for us, as the heat produced by glowing lava is unbearable if you get too close. But up on the rim, 80 metres away, the heat was tolerable and so we were able to observe and photograph the spectacle of fire in the chamber of hell throughout the days and nights we spent there.
At present there are only six lava lakes on earth. Two are bubbling away in the craters of Kilauea volcano on Hawaii, the largest currently on earth is the one in the crater of the 3470 meter high Nyiragongo volcano in the Democratic Republic of the Congo in east Africa, on Mount Erebus in the Antarctic, in the crater of the Ambrym volcano in the South Sea archipelago of Vanuatu – and also in a pit crater of the Erta-Ale volcano in the Danakil desert of Ethiopia.