While the challenge of cleaning up Mount Fuji has been at the forefront of public attention and action, the possibility of a near-future volcanic eruption is a threat that poses far greater consequences. In fall 2000, Japanese scientists began detecting a surge in activity inside the volcano: a significant increase in small tremors—more than 200 a month compared to prior averages of 10 per month—and the movement of magma, possibly toward the surface. This activity, the scientists said, indicated that the volcano could possibly erupt sometime soon. Mount Fuji’s last eruption, in 1707, lasted 16 days and produced a 6-mile-wide cloud of smoke and ash that blocked out the sun in some areas. A government report issued in 2002 said a new eruption could spew lava, debris and ash over hundreds of square miles—threatening nearby villages, cutting off electricity and water supplies, and disrupting road, rail and air travel. Resulting damage could cost up to $21 billion.