It became easier to predict the type of volcanic eruption: indicators of magma viscosity helped

The properties of the magma within the volcano affect how the eruption takes place. In particular the viscosity

molten rock is a major factor in how dangerous an eruption will be to nearby communities.

Very viscous magmas are associated with more powerfulexplosions. This is because they block the escape of gas through the "ventilation" holes in the soil. This creates pressure inside the "plumbing" of the volcano. On the other hand, the displacement of the more viscous magma results in slower lava flows.

The problem is that the viscosity of magma is usuallyis quantified only after the eruption, not in advance, explains Diana Roman of Carnegie University. She has carried out new work to determine the viscosity index of magma, which can be measured before the eruption. This will help scientists and emergency monitoring experts understand possible patterns of future eruptions. Results published in the journal Nature.

Lava fountain from the most productive fractureThe eruption, then called Fissure 8 and now called Ahuaylaau, formed a cinder cone 55 meters high, approximately equal to the height of a 10-storey building. Most of the 0.8 cubic kilometers of lava erupted in the lower East Rift Zone in 2018 erupted from this point. Credit: B. Shiro, US Geological Survey.

In 2018, the first eruption occurred in the lowerparts of the East Kilauea Rift Zone since 1960. The first of 24 cracks opened in early May, and the eruption lasted exactly three months. The situation has provided unprecedented access to information for many researchers. Namely, there is a lot of simultaneous data on the behavior of high and low viscosity magma, as well as on stresses before eruption in solid rock beneath Kilauea.

Tectonic and volcanic activitycause the formation of cracks, called faults, in the rocks that make up the earth's crust. When geological loads force these faults to move relative to each other, geophysicists measure the three-dimensional orientation and movement of the faults with seismic instruments.

May 2018. Credit: B. Shiro, US Geological Survey.

Studying what happened in the lower EastIn the Kilauea Rift Zone in 2018, Roman and her colleagues determined that the direction of movement of faults in the lower East Rift Zone before and during a volcanic eruption could be used to estimate the viscosity of rising magma.

“We were able to show that with the help of a reliablemonitoring, we can link the pressure and stress in the water supply system of the volcano with the underground movement of more viscous magma, - the author of the study concludes. "This will enable disaster monitoring experts to better anticipate volcanic eruptions such as Kilauea and develop response strategies in advance."

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