Look out below. Mount Kusatsu-Shirane, less than 100 miles from Tokyo, erupted today, raining rocks and ash down the mountain. It’s not clear if that’s what triggered a subsequent avalanche, which trapped several skiers — including military personnel conducting a training exercise. One of the soldiers died, and at least 12 other people were injured, some seriously. Authorities have warned people to avoid the mountain. Meanwhile, scores of skiers are trapped at a gondola station, with rescuers considering a snowmobile operation but hampered by snow and ash on the slopes.