A gigantic magmatic lake has been hiding underneath a dormant volcano in Bolivia, says international team of scientists. The lake consists of a water body with partially molten rock. Its temperature is estimated to be around 1,000 degrees Celsius. Its location: 15 kilometres down dormant volcano Cerro Uturuncu in the Bolivian Altiplano.
This is, obviously, quite unusual for a volcano. But who knows, maybe many more volcanoes have hidden lakes, and we haven’t just discovered them yet!
“The Bolivian Altiplano has been the site of extensive volcanism over past 10 million years, although there are no currently active volcanoes there,” says study author Professor Jon Blundy.
“The Altiplano is underlain by a large geophysical anomaly at depths of 15 km below the surface of Earth.
“This anomaly has a volume of one-and-a-half million cubic kilometres or more and is characterised by reduced seismic wave speeds and increased electrical conductivity. This indicates the presence of molten rock.
“The rock is not fully molten, but partially molten. Only about 10 to 20 percent of the rock is actually liquid; the rest is solid. The rock at these depths is at a temperature of about 970°C.”
According to the researchers, their findings will help decipher the ‘why’ and the ‘how’ behind (underneath) volcanoes.
When the team conducted high-temperature-and-pressure experiments to evaluate the characteristics of the molten part of the water body, they found that around 8 to 10% of water must be present in the silicate melt. Blundy says that this value is a relatively large one. To give you an idea, that quantity of water is representative to a total mass of water that is tantamount to what is found in enormous freshwater lakes found in the US.
“Ten per cent by weight of dissolved water means that there is one molecule of water for every three molecules of silicate. This is an extraordinarily large fraction of water, helping to explain why these silicate liquids are so electrically conductive,” says Professor Fabrice Gaillard (co-author).
Blund also says that silicate melt will only dissolve water at conditions of high pressure; otherwise, low pressure will cause the water to come out of solution, forming bubbles. This discovery is pertinent to the study of volcanoes as these bubbles are thought capable of triggering volcanic eruptions. Understanding the relationship between water and volcano activity might help scientists forecast when one will erupt.
The study is published in Earth and Planetary Science Letters.