Friday 18 November 2016

Tourist dies after falling into hot spring at Yellowsone National Park.

A man has died after falling into a hot spring at Yellowstone National Park in Wyoming, USA. The incident happened in June this year, but details of the event have only become clear following a Freedom of Information Act request by a local radio station. Colin Scott, 23, of Oregon was reportedly visiting the park with his sister on 7 June when he left a designated boardwalk in the Norris Geyser Basin in order to investigate the temperature of a pool, apparently with the intention of  'hot-potting' (getting into the pool and soaking), a practise strictly forbidden in the park. However he slipped and fell into the pool, possibly after being scalded by the water, and was rapidly killed by the hot and acidic water. Attempts to recover his body that day were unsuccessful, in part due to a large thunderstorm in the area, and by the next day little was left of the body.

Boardwalk across the Norris Geyser Basin in the Yellowstone National Park. InSapphoWeTrust/Wikimedia Commons.

The Yellowstone National Park lies on top of the caldera of an active volcano. The hot springs are fuelled by water from the surface peculating through the ground until it encounters hot rocks or magma, which heats it rapidly. This hot water then rises back to the surface to fuel the geysers and fill the volcanic pools of the park. As it passes through the rocks the water absorbs chemicals from the surrounding minerals, with water with different mineral properties in different parts of the park, creating a variety of brightly coloured pools. 

  Yellowstone is home to one of the world’s largest active volcanic systems. Cataclysmic eruptions in the past few million years created huge volcanic depressions called “calderas.” The youngest, the Yellowstone Caldera, was formed 640 000 years ago. Since then, about 80 eruptions of rhyolite (thick, sticky lava) and basalt (more-fluid lava) have occurred. The caldera’s interior is largely covered by rhyolites, most erupted in the past 160 000 years. Large hydrothermal (steam)-explosion craters formed in the past 14 000 years are located near Yellowstone Lake and in major geyser basins. Recent earthquakes (1973 to 2002) were concentrated between Hebgen Lake and the Norris Geyser Basin and along faults. USGS.

Many of these pools are alkaline in nature, but the pools of  the Norris Geyser Basin are acid, with a typical pH of about 3.5. This is not immediately dangerous, being roughly as acidic as vinegar, Lemon juice or some fizzy drinks. However the water in the pool was about 100°C (i.e. boiling), hot enough to quickly kill anyone falling in. Once immersed in such a pool the acid would rapidly attack the body, as, like most chemical reactions, acids act more strongly at higher temperatures.

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