Giant Earthquakes May Help Predict Future Volcanic Eruptions

There may be a new way to predict volcanic eruptions. Scientists have observed the response of Japanese volcanoes to seismic waves produced by the giant Tohoku-oki earthquake of 2011, which may shed some light on how earthquakes can impact volcanoes.

Seismic noise has often been removed from seismological analyses in the past, though now researchers have realized its uses. This background noise is actually associated with seismic waves caused by ocean swell. These waves, which can be compared to permanent, continuous microseisms, can be used by seismologists instead of earthquakes to image Earth's interior and its evolution over time, rather like an ultrasound scan.

In this case, the researchers used seismic noise in order to measure the perturbations of the mechanical properties of Earth's crust. More specifically, they utilized the Hi-net network, which is the world's densest seismic network.

After the Tohoku-oki earthquake of 2011, researchers analyzed over 70 terabytes of seismic data from the network. This allowed them to show where the perterbations of Earth's crust were the greatest were not those where the shocks were the strongest. Instead, they were localized under volcanic regions, especially under Mount Fuji. This allowed the scientists to also see the anomalies caused by the perturbation from the earthquake in volcanic regions under pressure.

Although no eruption has followed the Tohoku-oki earthquake, the 6.4-magnitude seism that occurred just four days after the 2011 quake confirms the critical state of the volcano in terms of pressure.

The findings reveal how regions affected by high-pressure volcanic fluids can be characterized using seismic data from dense seismic detector networks. This, in particular, may help anticipate the risk of major volcanic eruptions.

The findings are published in the journal Science.