Rapid swell recorded before volcano eruption

September 13 () –

For the first time, the surrounding terrain of a volcano has been detected and tracked as it swells like a compressed balloon. when it is about to erupt.

This is a short-term movement technically called ‘transient deformation’ and geoscientists from Virginia Tech They have observed it in satellite images of Ol Doinyo Lengai, an active volcano in Tanzania. Results published in Geophysical Research Letters.

According to the study, increased pressure inside a volcano’s magma reservoir can cause the terrain to bulge. When the pressure decreases, the reservoir deflates again and the terrain falls back down.

“We have been able to detect transient movement in volcanic activity, and this is a precursor to any type of eruption.“, said in a statement Ntambila Daud, a graduate student working with Associate Professor D. Sarah Stamps at Virginia Tech’s Geodesy and Tectonophysics Laboratory, said: “This research could help Tanzanian authorities get a better idea of ​​what’s happening with the volcano.”

Tanzania’s Ol Doinyo Lengai volcano (meaning “mountain of God” in the Maasai language) is the only active volcano in the world that produces carbonatite lavawhich has an unusual colour: when it erupts it is black or grey, but when it cools it turns bone white. The eruptions represent a constant threat to the surrounding communities and compromise tourism and air traffic in the area.

Records of Ol Doinyo Lengai eruptions date back to the 1880s. Since then, the volcano has been periodically active. Observations were irregular until 2016, when the Virginia Tech team installed six sensors on the volcano’s flanks to collect high-precision geodetic data taken from Global Navigation Satellite Systems (GNSS). Those data and data products allow a researcher to better measure and understand the geometric shape of the Earth. In addition, a seismometer on site monitors localized tremors and swelling around the volcano.

Using the GNSS data streams, Daud created computer models that detect possible volcanic signals at Ol Doinyo Lengai due to changes in the magma reservoir. The team evaluated seven years of continuous GNSS data for transient and found a rapid rise spanning from March 2022 to December 2022 and then a steady-state rise until August 2023.

“If the difference between the data and the expected pattern is three times larger, it indicates a transient deformation in the surface motion,” Daud said. “This could indicate an imminent eruption and help forecast eruptions.”

In addition to serving as a possible early warning system For the communities surrounding Ol Doinyo Lengai, this technique has been applied to other volcanoes such as the Long Valley Caldera in California and Alaska’s Akutan Volcano.

“The approach Daud used in this paper provided important advances in our understanding of the dynamic magma plumbing system at Ol Doinyo Lengai,” Stamps said.