Highlighted the interactive process between the ascent of magma, eruptions and sliding towards the sea of the eastern flank of Etna, often associated with seismic events.
The sliding of Etna's eastern flank acts as a valve which favors or inhibits eruptions in the sector immediately upstream; the variation of the sliding speed itself can be considered as a sentinel for any paroxysmal eruptions and/or magma intrusion processes. This is the result achieved in the study just published in the US journal Geology entitled "Flank sliding: A valve and a sentinel for paroxysmal eruptions and magma ascent at Mount Etna, Italy”, the result of the work of a team of researchers from the National Institute of Geophysics and Volcanology (INGV) and the Higher Institute for Environmental Protection and Research (ISPRA)
"Through a multidisciplinary approach that has seen the use of SAR remote sensing, GPS and seismic tomography", explains Giuseppe Pezzo, author of the research, "we analyzed the deformations of the ground in the Etna area related to the eruptive event of 24 December 2018 and to the seismic event that occurred two days later, on 26 December". "In particular”, continues the researcher, “SAR satellite interferometry, through the use of radar satellite images, has allowed us to obtain ground deformation maps of the whole Etna area. The measurements obtained were integrated with those coming from the GPS network, which continuously measures the movements of the volcano. Finally, with seismic tomography, through the study of seismic waves, the structure underneath the volcanic edifice was reconstructed. This complex multidisciplinary analysis has highlighted how the continuous movement of Etna's eastern flank has favored, over time, the intrusion of magmas in the area immediately upstream of the collapse itself, in the fracture zones known as the North-East Rift and South of the summit area of the volcano. The geometry and location of these magma volumes appears to be consistent with ancient tectonic structures, highlighted by seismic tomography data, which displace the crust under the volcanic edifice, favoring the ascent of magma towards the surface".
“The magmatic risings”, continues Mimmo Palano, co-author of the research, "because of the internal pressures of the magma, they cause an enlargement of several meters of the entire volcanic edifice and give an acceleration to the movement of the eastern flank".
“This acceleration” concludes Claudio Chiarabba, co-author of the research”, determines, in turn, two effects: it causes seismic events along the faults bordering the unstable flank (such as, for example, the earthquake of 26 December 2018 with a magnitude of 4.9 along the Fiandaca fault), and generates a depressurization of the affected by the eruption, stopping it".
#ingv #etna #eruptions #earthquakes
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Flank sliding: a valve and a sentinel for paroxysmal eruptions and magma ascent at Mount Etna.
Researchers highlighted the interactive process between the magma ascents, the eruptions and the seawards sliding of the eastern flank of Mount Etna, frequently associated with seismic events.
The sliding of the eastern flank of Etna acts as a valve that favors or inhibits eruptions back to sliding plane; the variation of the sliding velocity could be considered as a sentinel for possible paroxysmal eruptions and/or deep resourcing of the magma reservoir.
This is the result achieved in the study just published in the US journal Geology entitled "Flank sliding: A valve and a sentinel for paroxysmal eruptions and magma ascent at Mount Etna, Italy". The study was conducted by a team of researchers from the Italian National Institute of Geophysics and Volcanology (INGV) and from the Italian Institute for Environmental Protection and Research (ISPRA).
"By means of a multidisciplinary approach embracing SAR remote sensing, GPS and seismic tomography", explains Giuseppe Pezzo, author of the research, "we analyzed the ground deformations of the Etna volcano related to the 24 December 2018 eruptive event and to the seismic event that occurred two days later, on 26 December". "In particular", continues the researcher, "satellite SAR interferometry, using radar satellite images, allowed us to obtain ground deformation maps of the Etna area. The obtained measurements were integrated with data coming from the GPS network, which continuously measures the displacements of the volcano. Finally, seismic tomography methods, through the study of seismic waves, allowed us to reconstruct the structure underneath the volcanic edifice.This complex multidisciplinary analysis highlights how the continuous slip of the eastern flank of Etna over time favors the magma intrusion eruptions back to sliding plane itself, in the volcano summit fractures, known as the North-East and South Rift. The geometry and location of the magma volumes are consistent with ancient tectonic structures dislocating the crust under the volcanic edifice, as highlighted by seismic tomography data, and favoring the upward magma ascent".
"The magma rising", continues Mimmo Palano, co-author of the research, "due to the internal pressures, causes a few meters widening of the entire volcanic edifice and gives an acceleration to the eastern flank collapse".
"In turn, this acceleration" concludes Claudio Chiarabba, co-author of the research "determines two effects: it causes seismic events along the faults bordering the unstable flank (such as, for example, the Magnitude 4.9 earthquake occurring on 26 December 2018 along the Fiandaca fault), and the cessation of the eruption for the sudden depressurization back to the collapse plane".
#ingv #etna #eruptions #earthquakes
Figure 1 Valle del Bove (Mount Etna, 2019). In the image you can see the lava flow of December 2018
Figure 1 Valle del Bove (Mount Etna, 2019). Picture shows the December 2018 lava flow.
Figure 2 - A) Movements recorded by GPS stations between 22 and 28 December 2018; seismic events are also represented. B) Map of the Etna area showing the displacement speeds measured between 28 December 2018 and June 2019, through SAR interferometry, along the line of sight of the satellite. Arrows represent GPS speeds over the same time interval. In panels A and B the red arrows represent the observed measurements, while the yellow ones are the analytical model calculated to define the strain source. On the right are the eastward movements recorded by some GPS stations between 28 December 2018 and June 2019.
Figure 2 - A) Ground displacements measured by GPS stations in 22-28 December 2018 time interval; Seismic events are also reported. B) Etna area map showing displacement velocities along the line of sight of the satellite, obtained by means multitemporal SAR interferometry technique, in the 28 December 2018 and June 2019 time window. The arrows represent the GPS velocities in the same time span. In panels A and B, the red arrows are the observed measurements, whereas the yellow ones represent the analytical model calculated to define the deformation source. On the right, the corresponding GPS displacement time series showing the eastward acceleration until June 2019.
Figure 3 - Schematic representation of the processes in progress.
Figure 3 – Schematic representation of the processes in progress. Inset represents depressurization vertical profiles due to flank collapse, back to sliding plane.