© Japan Stock/AlamyWhat's going on below?
A team led by Takayuki Kaneko at the University of Tokyo's Volcano Research Center has found that over the centuries the magma's silica levels have gradually increased. High silica tends to indicate large explosions, suggesting eruptions have become more violent. Large amounts of basalt rich in aluminium oxide were also found, which can trigger an eruption when it collides with silica.
Based on the pressures required to form both materials, Kaneko believes the two mineral composites are housed in separate chambers under Fuji: one deep chamber 20 kilometres below the volcano, rich in basaltic magma, and a shallower chamber housing the silica 9 kilometres underground.
He says the deep rumble of low-frequency earthquakes beneath Fuji in 2000 and 2001 suggests movement inside the basaltic magma chamber, and adds he would not be surprised if Fuji erupts in the very near future.
