A team at the University of Tokyo has found that the ratio of atoms in specific gases released from volcanic fumaroles (gaps in the Earth’s surface) can be an indicator of what is happening to the magma deep below.
More specifically, changes in the ratio of argon-40 and helium-3 can indicate how frothy the magma is, signaling the risk of different types of eruption. Knowing which rations of which gases indicate a certain type of magma activity is a big step. Next, the team wants to develop portable equipment which can provide on-site, real-time measurements for a 24/7 volcanic activity monitoring and early warning system.
Fumaroles are holes and cracks in the Earth’s surface which release gas and steam and often occur near volcanoes. The ejected gas is composed of a mix of chemicals. Its make-up can provide us with insight into what is happening below the Earth’s crust in the mantle, where magma forms and pushes upwards, eventually erupting as lava. Researchers already know that the ratio of isotopes of specific gases can indicate hidden magma activity.
“We succeeded in detecting changes in the magma-derived argon-40/helium-3 ratio, related to magmatic unrest. Using computer models, we revealed that the ratio reflects how much the magma underground is foaming, making bubbles of volcanic gases which separate from the liquid magma,” said professor Hirochika Sumino from the Research Center for Advanced Science and Technology.
“How much magma foams controls how much magmatic gas is provided to the hydrothermal system beneath a volcano and how buoyant the magma is. The former is related to a risk of phreatic eruption, in which an increase in water pressure in the hydrothermal system causes the eruption. The latter would increase the rate of magma ascent, resulting in a magmatic eruption.
https://phys.org/news/2022-11-frothy-magma-gases-evade-disaster.html