Mount Fuji, the graceful conical volcano that rises within view of the Tokyo metropolitan area, is slowly changing shape and could erupt over a wider area than previously predicted, researchers said Monday.
"It wouldn't be strange for an eruption to occur anywhere on the mountain now," said lead researcher Shigeru Suto from the National Institute of Advanced Industrial Science and Technology.
"Right now only slow movements are occurring. Before an eruption, those movements become much more abrupt," Suto said. Still, he urged officials to reconsider current disaster-prevention measures and evacuation plans.
The 3,776-meter peak lies just 100 km from the Tokyo area, where over a fifth of Japan's 120 million people live. The government has said an eruption could cause up to 2.5 trillion yen in damage.
Previously, experts believed pressure from fissures in the Earth's crust was building along a diagonal line running southeast to northwest beneath Mount Fuji, roughly parallel to a line along which several tectonic plates converge. But the team's findings show the mountain is being compressed in a north-south direction, Suto said.
Tectonic plates are slabs of the Earth's crust, and earthquakes and volcanic activity are common where they converge.