When a Volcano Kills Quietly
Discovery News, By Michael Reilly | Mon Mar 15, 2010 03:21 PM ET
In June of 1996 New Zealand's Mt. Ruapehu erupted with violence. Its ash cloud blotted out the sun for miles, climbing almost 30,000 feet into the atmosphere. In all, some 7 million tons of rock and ash were ejected.
Yet no one was killed. At least, not within 60 miles of the volcano.
But in the cities of Auckland and Hamilton, hundreds of miles from Ruapehu, something strange happened. No warnings were sounded, and the skies appeared normal to the naked eye. But more people than usual started showing up at hospitals, many of them later dying of aggravated respiratory diseases.
A city of 1.3 million people, Auckland is 175 miles from the volcano -- that would seem to be a safe distance. But respiratory deaths there and in Hamilton were higher in 1996 than any other time that decade.
That's exactly the researchers' point. The scientists point out that all sorts of eruptions -- from Mt. St. Helens in 1980 to the epic Laki fissure eruption of 1783 in Iceland -- throw out loads of microscopic particles that are much more dangerous to people's lungs than the bits of ash we can see.
In fact, people further away from volcanoes may suffer worse exposure than those living right next to it, because small particles will initially go thousands of feet in the air and get carted away by wind.
If you're one of the 500 million people on Earth living with a 60-mile bulls eye of an active volcano, then you know you have a problem. What this research is saying is that if you live much further away, you may not be still be in trouble -- maybe worse trouble, because no one sees it coming. They write:
...the long-distance dispersal of diffuse fine volcanic ash and gaseous aerosols may pose a far more extensive health hazard than is generally perceived by medical and civic authorities. If so, people in many large cities, with limited or no awareness of this threat and no effective emergency procedures, may be at risk.
Image: Global Volcanism Program
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