By Marci Wills, April 18th, 2010
It seems that Earth is especially determined to show off its tricks this year. The ongoing eruption of Eyjafjallajokull (how do you pronounce that?) volcano in Iceland this week serves as yet another powerful reminder that we must organize our lives around the unpredictable workings of our planet. The continued cessation of air travel across Europe due to Eyjafjallajokull’s ash cloud is more than a slight inconvenience, but the research of Hildur Gestsdottir of the Institute of Archaeology in Rejkjavik suggests that the eruption may pose an even more severe threat. She believes that hydrofluoric acid emmitted from the Icelandic volcanoes has killed hundreds, if not thousands, of Europeans in previous severe eruptions.
Iceland’s most devastating eruption of historic time was that of the offshore volcanic peak, Laki, in 1783. Laki spewed ash into the air over 8 full months and 10,000 Icelanders (roughly 1 in 5) died. Laki’s ash cloud altered European weather patterns, resulting in consecutively one of Europe’s hottest summers followed by its most severe winter on record in 1873, both of which were associated with higher than normal death rates in Europe that year. Still, Hildur Gestsdottir believed that there were other reasons behind why the death toll in Iceland was so high. Survivors of the Laki eruption noted that their sheep and other livestock developed knobby protrusions from their bones, a telltale sign of fluorosis, or fluoride poisoning, just before dying. When Hildur excavated late 18th century graves in 2004, she found that many of those buried just after the eruption showed similarly abnormal bone growths. Hildur believes that these people were drinking water with concentrations of 30 to 40 ppm of hydrofluoric acid, enough to make you feel sick, but the poisoned ash was so pervasive that they simply had no other option.
The current Eyjafjallajokull eruption is not expected to reach a Laki-like scale. The ash cloud is located at ~30,000 ft, unfortunately the same altitude at which planes fly, but luckily below the stratosphere where volcanic gases can have a global effect because of a lack of rain there. Atmospheric scientist Brian Toon of the University of Colorado Boulder expects that the ash cloud from Eyjafjallajokull will be washed away by rain as it drifts further to the east. Still, hydrofluoric acid may become a worry if the eruption continues much longer. Fluoride-rich volcanic ash clings to vegetation and may affect crops and livestock even at low concentrations. If continuously ingested at high concentrations, people and animals can begin to die within several months. The effects of fluoride-rich volcanic ash are not fully understood as such Fluoride-rich lava is characteristic only of the volcanoes in Iceland and some in Melanesia.
Iceland has about 130 volcanoes, 18 of which have erupted since the settlement of the island in 900 C.E. Events of the scale of the Laki disaster are expected to occur there every 500 to 1000 years. As part of learning to survive on our planet, it is important to consider the challenges of keeping food and drinking water fluoride-free (and free of other various volcanic poisons) in the midst of air traffic, and possibly communication, shutdown due to volcanic eruptions.
Stone, R., 2004, Iceland’s Doomsday Scenario: Science, News Focus, v. 306, p. 1278-1281.