Shear-Wave Splitting for Volcanic Monitoring

Current Context: Researchers from the University of Oxford have introduced a novel method for monitoring volcanic activity by analyzing shear-wave splitting at Mount Ontake, Japan. This technique aims to provide early warnings for eruptions by detecting stress-induced changes in the Earth’s crust.

About Shear-Wave Splitting:

• Definition: Shear-wave splitting occurs when seismic shear waves divide into two polarized waves traveling at different speeds due to aligned cracks or fractures in rocks.
• Functionality: The movement of magma and volcanic fluids alters stress conditions, causing cracks to open or close. These changes affect shear-wave propagation, allowing scientists to monitor subsurface stress variations.
• Significance: Increased shear-wave splitting indicates rising internal pressure, serving as a potential early-warning signal for volcanic eruptions.

About Mount Ontake:

• Location: An active stratovolcano on Honshū Island, central Japan, and the country’s second-highest volcano.
• Notable Event: Experienced a deadly phreatic eruption in 2014, which occurred without significant seismic warning, resulting in over 60 fatalities.