Alaska's Mount Churchill volcano erupted some 1,200 years ago, spreading ash from Canada to Germany... Mount Churchill is also an impressive volcano, the tallest on land in the United States and one of the towering, snowy peaks of Alaska's Wrangell-St. Elias Mountains. But Churchill's blast in A.D. 843 ejected just 12 cubic miles (50 cubic km) of ash, a layer now called the White River Ash, according to the new study, published in the September 2014 issue of the journal Geology... If moderate volcanic eruptions can spread ash for thousands of miles, then these blowouts may be more hazardous than...