Powerful volcanoes remind us of the fragile boundary between Earth's crust and mantle, finds Laura Spinney.
Natural History Museum, Geneva, Switzerland Until 4 September 2011
The eruption of the Icelandic volcano Eyjafjallajökull this April, and the month-long havoc it caused in the skies over Europe, was a salutary lesson in how susceptible our global, interconnected society is to natural perturbations. This saga and other spectacular eruptions are explored in the exhibition Supervolcano at the Natural History Museum in Geneva, Switzerland.
The highlight is the display of photographs by Geneva's volcanology society. These self-confessed volcano addicts travel the world to record the beauty and devastating impacts of the latest eruptions. The images attest to the many ways that volcanoes can kill you — through flying debris, burns, asphyxiation or being struck by the lightning generated within the columns of charged particles they eject.
Interactive installations convey the volcanic experience. Visitors can feel seismic tremors, listen to a mud volcano and walk through a reconstructed lava tunnel. The destructive power of volcanic ash is revealed in a mock-up of a crushed office: it is the weight of settled ash that causes buildings to cave in.
Other displays explore the wider societal risks of massive eruptions and their historical influence. Eyjafjallajökull was a relatively modest geological event, but volcanologists fear that it might trigger a far more dangerous neighbouring volcano, Katla, now under high surveillance. If Katla blows, the fallout could put April's upset in the shade.
The 1783–84 eruption of Laki, another Icelandic volcano, might have contributed to the French Revolution a few years later. Laki's toxic cloud polluted the atmosphere, lowered temperatures and caused famines across the Northern Hemisphere.
Even more destructive are supervolcanoes — eruptions with the maximum score of eight on the Volcanic Explosivity Index, measured according to the volume of material ejected, among other factors. Eyjafjallajökull qualified as a four. The eighteenth-century Laki eruption and the 1991 eruption of Mount Pinatubo in the Philippines — which spewed out 10 cubic kilometres of debris — both scored a six.
No known supervolcanoes are currently active, although the imploded remains of one lie in Yellowstone National Park in Wyoming. From the size of its caldera, researchers think that it dumped ash across much of the continent about 640,000 years ago. Toba in Sumatra was one of the last supervolcanoes to erupt, 75,000 years ago. Forty kilometres away is Mount Sinabung, which erupted last month after a long period of inactivity. It too is being monitored closely.
This timely exhibition reminds us of our vulnerability to volcanoes; we inhabit Earth's cool, thin crust, but more than 99% of the planet smoulders at temperatures above 1,000 °C.
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Spinney, L. Earth science: Fire from the depths. Nature 467, 399 (2010). https://doi.org/10.1038/467399a