New Zealand sits at the margin of the Pacific and Australian plates, and their collision makes volcanic activity commonplace. Even so, the eruption this past summer of Mount Ruapehu, on the country’s North Island, was the most spectacular in more than a century. On June 17 the volcano began hurling clouds of ash and billowing smoke 20,000 feet into the atmosphere; chunks of molten rock, some of them reportedly the size of cars, flew hundreds of feet. At one time or another the ash clouds closed 11 airports, and ash that washed into the water intake of one major hydroelectric plant caused $6.5 million in damage. The North Island’s two largest ski resorts, located on the flanks of Ruapehu, were also closed-- right at the beginning of New Zealand’s ski season. Although the skiers stayed home, amateur volcano watchers came from around the globe. Ruapehu has had a very large impact because it was so well covered by the media, with images going out around the world, says volcanologist Bruce Houghton of New Zealand’s Institute of Geological and Nuclear Sciences. But on a global scale the eruption was tiny--perhaps one one-hundredth the size of Pinatubo. We didn’t have a single foreign volcanologist visit.