Short summary of the article “Torfajökull's magmatic plumbing system with seismic interferometry and phase-velocity surface-wave tomography”, published in Journal of Geophysical Research
J. E. Martins, E. Ruigrok, D. Draganov, A. Hooper, R.F. Hanssen, R.S. White, H. Soosalu
Published in JGR Solid Earth 2019, https://doi.org/10.1029/2018JB016002
The Torfajökull volcano in south Iceland is characterized by intense geothermal activity, deformation, and seismicity. It has a caldera 12 km in diameter. Although it has not erupted since 1477, the manifestations of activity suggest a long-lasting magmatic system. Outlining the magmatic plumbing system is a key element for predicting future eruptions of a volcano.
We use ambient seismic noise to produce a tomographic image of the magmatic system beneath the Torfajökull volcano. This technique allows us to detect velocity variations and contrasts of seismic waves due to changes in rock composition, density, temperature or pressure in the subsurface. We identify high-velocity variations outlining the volcano caldera at 4-5 km depth and more pronounced high velocities at shallower depths in the north section of the volcano caldera.
We interpret the first as a possible caldera collapse structure and the latter as solidified (and dense) intrusive magma from old preferred magma paths. The tomographic results also indicate low-velocity anomalies beneath the volcano caldera, and even lower velocity variations in the SE and SW study area, outside the volcano caldera. The most prominent low-velocity features are located outside the volcano caldera outskirts. These anomalies may indicate the existence of hot material (molten or partially molten rock).
As a result of this study, a conceptual model of the inner structure of Torfajökull is presented.
Figure: Martins et al., 2019
