Japan's 2011 earthquake raised pressure under Mount Fuji
Tuesday, July 15, 2014, 6:21 PM - The magnitude 9.0 earthquake that devastated Japan on March 11, 2011 increased pressure under Mount Fuji, putting the volcano in a "critical" state -- but the new study by French and Japanese scientists may raise as many questions as it answers.
For starters, researchers don't think the elevated pressure means an eruption is imminent.
"We cannot establish a direct relation of cause and effect between quakes and volcanic eruptions, even if statistically the former lead to an increase in the latter," Florent Brenguier, a researcher at the Institute of Earth Sciences (IST) in Grenoble, France told the Guardian.
"All we can say is that Mount Fuji is now in a state of pressure, which means it displays a high potential for eruption. The risk is clearly higher."
The conclusion was made by analyzing data recorded by Japan's hi-net system which is equipped with 800 seismic sensors.
The team zoned in on signals that are referred to as "seismic noise", a generic term describing persistent vibrations in the ground due to a number of causes.
RELATED: What are 'sonic boom' earthquakes?
This is unusual in itself: According to the Guardian, this "noise" is often dismissed by scholars as background noise of little use.
By studying subtle fluctuations around the time of the 2011 quake, scientists discovered that the Earth's crust was most damaged near Japan's volcanic regions, some 400 kilometres away from the quake's epicentre.
Brenguier told the Guardian that the 2011 seismic waves combined with boiling water, gas and liquid magma under the surface of Mount Fuji to elevate pressure.
While the volcano is now at a higher risk of erupting, there is no way to accurately predict when that will occur.
Mount Fuji's last eruption was in 1707, several weeks after a magnitude 8.7 quake.
The new paper has been published in the journal Science.