Scientists and emergency officials on Tuesday warned people living near Mount Usu in southern Hokkaido to brace for a possible large-scale volcanic eruption following reports of heightened seismic activity in the mountain.
The Meteorological Agency issued an emergency volcano warning at 2:50 a.m. Tuesday after the frequency of tremors at the 732-meter mountain began accelerating.
In addition to 38 tremors that could be felt by humans, 16 more were recorded between 8 a.m. and midnight Monday and 376 from midnight until 3 p.m. Tuesday. Two tremors with a magnitude of 3.1 on the Richter scale were recorded shortly after noon and around 4:11 p.m. The mountain normally logs 20 to 30 tremors a month, the agency said.
The Coordinating Committee for Prediction of Volcanic Eruption held a top-level meeting of experts at the agency Tuesday.