- Geophysicists found they could map the course of an eruption by matching gas sounds in a volcano's magma chamber to gas flow out of vents.
- When the vents stop emmiting gasses the eruption is over.
When volcanoes erupt, they create a stunning visual spectacle for anyone watching, but they also emit impressive noises that range from low rumbles to concussive blasts. Some of the sounds are below the range of human hearing, and a new study suggests they can be used to better understand and monitor eruptions.
Geophysicist Aurélien Dupont of the Pusan National University in South Korea studied the low-frequency sounds made by gases percolating through basaltic magma, a type of magma that flows easily because it has a low viscosity (or, roughly, thickness) and gas content. Volcanoes that spew basaltic lava tend to have gentle slopes, making impressive eruptive displays of rivers of lava running down their sides.
As the magma travels from the volcano's underground magma chamber, pockets of gas trapped inside it expand (and produce the low-frequency sound, or infrasound) until they reach the surface, where the gas can bubble away into the atmosphere.