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.

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.

Shear-Wave Splitting FAQs

Q1. What is Shear-Wave Splitting?
Ans. Shear-Wave Splitting refers to the phenomenon where seismic shear waves (S-waves) split into two polarised waves as they pass through anisotropic Earth materials.

Q2. Why is Shear-Wave Splitting significant in geophysics?
Ans. It helps scientists study the Earth's internal structure, including mantle deformation and tectonic stress patterns.

Q3. What does it reveal about earthquakes?
Ans. It can provide early insights into stress accumulation and fault dynamics, aiding in earthquake hazard assessments.

Source: PHY