Jon Major/U.S. Geological Survey
April 1, 2010
In this 2008 file photo provided by the U.S. Geological Survey, a tripod-suspended set of geological monitoring instruments called a “spider” is shown on the Northwest Rim of Mount St. Helens. Two similar spiders are headed to Chaiten, a volcano in Chile that began erupting in 2008 after about 9,000 years of dormancy, sometime this spring, marking the first time the spiders have been used internationally.