Shear-Wave Splitting

Shear-Wave Splitting Latest News

The University of Oxford scientists have proposed a new method for monitoring volcanic eruptions using a seismic phenomenon called shear-wave splitting at Mount Ontake, Japan.

What is Shear-Wave Splitting?

• Shear-wave splitting refers to the phenomenon where seismic shear waves travel at different speeds based on their polarisation, especially when passing through aligned cracks or fractures in rocks.
• As magma and volcanic fluids move underground, they alter stress conditions, causing cracks in surrounding rocks to open or close. These changes affect the speed and direction of shear-waves, which scientists can monitor.
• The degree of shear-wave splitting increases when internal pressure builds up, offering a potential early-warning signal for impending eruptions.

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About Mount Ontake

• Mount Ontake is an active stratovolcano located in Honshū Island, Central Japan, near Tokyo. It is Japan’s second-highest volcano and part of the Pacific Ring of Fire.
• The volcano experienced a deadly phreatic (steam-driven) eruption in 2014, which occurred without significant seismic warning, killing over 60 people, most of whom were hikers.
• Phreatic eruptions are hydrothermal explosions caused by steam pressure and do not involve new magma, making them hard to predict with conventional methods.

Source: PHY