By analyzing the minerals present in the rocks erupted by Stromboli during the paroxysms of 2019, the researchers discovered a temporal correspondence between the modifications that occurred in the magmatic feeding system and the changes in the state of activity of the volcano recorded by the monitoring networks in the months preceding the eruptions
The analysis of the crystals found within the products erupted by Stromboli during the paroxysms of 2019 highlighted a rejuvenation of the magmatic system and a significant consistency between the chemical modifications of the rocks that occurred in the month preceding the eruptions and the data recorded in the same time interval from monitoring networks.
These are the main findings of the study “Magma recharge and mush rejuvenation drive paroxysmal activity at Stromboli volcano”, just published in the scientific journal 'Nature Communications and carried out within the strategic departmental project 'UNO' of INGV. The research was conducted by an international team of researchers which involved the National Institute of Geophysics and Volcanology (INGV), the Natural History Museum of London (NHM - UK), the Institute of Geochemistry and Petrology of the Federal Polytechnic of Zurich (ETH - CH) and the Departments of Earth Sciences of the University of Keele (UK), the University of Iowa (USA), the Sapienza University of Rome, the University of Pisa (UniPI) and the of Ferrara (UniFE).
"The objective of our study was to investigate the magmatic dynamics of the Stromboli system and the changes that have occurred in the last twenty years, paying particular attention to the two paroxysms of summer 2019", explains Piergiorgio Scarlato, INGV volcanologist. “Among the most significant results we have obtained there is certainly evidence that the deep feeding system of Stromboli was re-fueled by the entry of new deep magma, hotter and rich in volatiles. The diffusion models applied to the chemical compositions measured on 65 crystals of clinopyroxene (a mineral always present in magmatic rocks erupted from Stromboli) showed that more than 70% of the ''recharge'' events of the volcanic system, recorded in the period of analysis, they started about a month before the eruption of July 3 (the first paroxysm of 2019), consistent with the observed increase in eruptive activity”.
By comparing the products of the last twenty years, the researchers were able to ascertain that the marked compositional and textural differences between the clinopyroxene crystals of 2019 and those of the eruptive activity of the previous years (2003-2017) show that the volcano's feeding system And 'rejuvenated' over time, through a process of erosion of the walls of the magma chamber and dissolution of the pre-existing crystals, which took place inside a highly crystalline body called 'mush'. Since the paroxysm of April 5, 2003, the abundance of this mush it gradually decreased in the erupted products, until it almost disappeared completely in the products of summer 2019.
“The clinopyroxene crystals present in the eruptive products of August 28, 2019 - the second paroxysm of 2019 - return recharge times of no more than one month due to the erosion of the mush and, therefore, different from those of July 3. This confirms that the paroxysm of August 28 was fueled by a second injection of magma, distinct from the magma that fueled the eruption of July 3, confirming the hypothesis of a 'rejuvenation' of the system", adds Scarlato. "These changes in the volcano's magma feeding system are probably among the underlying causes of the eruptive phenomena that have been repeating on Stromboli since the summer of 2019."
“A further important result of this work is the 'correspondence' found between the crystal-chemical modifications of clinopyroxene and the data recorded by surveillance cameras, geochemical stations on the volcano and networks for monitoring seismic tremor and ground deformation. This coherence between the parameters confirmed how the chemical-physical variations of the deep magmatic system are able to produce effects that can be observed well in advance, especially with respect to paroxysmal events". adds Elisabetta Del Bello, volcanologist at INGV.
"These results” highlights Piergiorgio Scarlato, “provide new elements of basic relevance for understanding the mechanisms of generation of paroxysms in Stromboli and, consequently, for the development of monitoring systems for eruptive activity"
The continuous monitoring of the products erupted by volcanoes such as Stromboli is therefore confirmed as a fundamental element for understanding the changes in the power systems of volcanoes and for reconstructing their time scale, with the ultimate aim of increasing the tools useful for defining strategies for assessing and mitigating natural risks.
The published research has an essentially scientific value, without immediate implications regarding the aspects of civil protection at the moment.
Link:
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STROMBOLI | The rejuvenation of the volcano discovered by analyzing the erupted products
By analyzing the minerals characteristics of the rocks erupted by Stromboli during the paroxysms of 2019, the researchers discovered a temporal correspondence between the modifications that occurred in the magmatic feeding system and the changes in the state of activity of the volcano recorded by the monitoring networks in the months preceding the eruptions
The analysis of the crystals found within the eruptive products of the Stromboli 2019 paroxysms highlighted a rejuvenation of the magmatic system and a significant consistency between the chemical modifications of the rocks that occurred in the month preceding the eruptions and the data recorded in the same time interval from monitoring networks.
These are the main results of the study"Magma recharge and mush rejuvenation drive paroxysmal activity at Stromboli volcano", just published in the scientific journal 'Nature Communications' and carried out as part of the INGV departmental strategic project 'UNO'. The research was conducted by an international team of researchers which involved the National Institute of Geophysics and Volcanology (INGV), the Natural History Museum of London (NHM - UK), the Institute of Geochemistry and Petrology of the Federal Polytechnic of Zurich (ETH - CH) and the Departments of Earth Sciences of the University of Keele (UK), the University of Iowa (USA), the Sapienza University of Rome, the University of Pisa (UniPI) and the University of Ferrara (UniFE).
"The objective of our study was to investigate the magmatic dynamics of the Stromboli system and the changes that have occurred over the last twenty years, paying particular attention to the two paroxysmal eruptions of the 2019 summer", explains Piergiorgio Scarlato, INGV volcanologist. “One of the most significant results obtained is the evidence that, before the proximal events, the deep feeding system of Stromboli has been replenished with new magma, hotter and rich in volatiles. Diffusion modeling on 65 clinopyroxene crystals (a mineral always present in magmatic rocks erupted from Stromboli) showed that more than 70% of the ''recharge'' events of the volcanic system, started about a month before the July 3 eruption (the first paroxysm of 2019), consistent with the observed increase in eruptive activityy".
By comparing the products of the last twenty years, the authors were able to ascertain that the marked compositional and textural differences between the 2019 clinopyroxene crystals and those of the 2003-2017 eruptive activity) is a result of the volcano's feeding system 'rejuvenation' over time, due to erosion of the magma chamber walls and dissolution of the pre-existing crystalline body called 'mush'. Starting from the paroxysm of April 5, 2003, the abundance of this mush gradually decreased in the erupted products, until almost completely disappearing in the products of summer 2019.
"The August 28 eruptive products (the second paroxysm of 2019) - display recharge times of no more than one month due to musherosion and, therefore, different from those of July 3. This confirms that the paroxysm of August 28 was fueled by a second injection of magma, distinct from the one driving the eruption of July 3, confirming the hypothesis of a 'rejuvenation' of the system", adds Scarlato. "These changes in the volcano's magma feeding system are probably amongst the underlying causes of the eruptive phenomena that have been repeating on Stromboli since the summer of 2019."
"A further important result of this work is the 'correspondence' found between the crystal-chemical modifications of clinopyroxene and the data recorded by surveillance cameras, geochemical stations on the volcano and the seismic tremor and ground deformation monitoring networks. This coherence between the parameters confirmed how the physico-chemical variations of the deep magmatic system are able to produce effects that can be observed well in advance, especially with respect to paroxysmal events", adds Elisabetta Del Bello, volcanologist at INGV.
"These results" highlights Piergiorgio Scarlato, "provide new insights on the mechanisms triggering paroxysmal eruptions at Stromboli and, consequently, improving the monitoring of the eruptive actvitiy"
The continuous petrological monitoring of the products erupted by persistently active volcanoes such as Stromboli is therefore confirmed as a fundamental element for understanding the changes in the magmatic feeding systems of volcanoes and for reconstructing their timescales, with the ultimate aim of implementing the tools useful for defining strategies for assessing and mitigating natural risks.
The published research has an essentially scientific value, without immediate implications regarding the aspects of civil protection at the moment.
Link:
Photo 1 - Product sampling and selection of pumice fragments erupted during the paroxysm of August 28, 2019 on the sides of the volcano. Photo P. Scarlato.
Ph. 1 - Products sampling and selection of pumice fragments erupted during the 28 August 2019 paroxysm on the slopes of the volcano. Photo P. Scarlato.
Photo 2 - ethers fallen on the helipist located near the summit area during the paroxysm of 3 July 2019. Photo E. Del Bello.
Ph 2 - Decimeter- to meter-sized bombs dropped on top of the helipad located near the summit area of Stromboli during the 3 July 2019 paroxysm. Photo by E. Del Bello.
Photo 3 - ; Sampling operations of the deposit of pumice and ashes of July 3 on the roofs of the houses of Ginostra. Photo E. Del Bello.
Ph 3 - Sampling operations of the lapilli and ash deposit of the 3 July paroxysm on the roofs of the houses in Ginostra village. Photo by E. Del Bello.
Image - Clinopyroxene crystal representative of the 2019 paroxysms seen with the Electron Microscope (left). Compositional zoning is observed as a change in gray tone towards the outer edge of the crystal, corresponding to an increase in magnesium, chromium and nickel (these two elements visible in the chemical maps on the right, chromium at the top and nickel at the bottom), due at the entrance of new, hotter and more primitive magma into Stromboli's feeding system. Image CMPetron.
Image -Scanning electron microscope image (on the left side) of a clinopyroxene crystal representative of the 2019 paroxysms. The compositional zoning determines a change in grayscale towards the outer edge of the crystal, which corresponds to an increase in magnesium, chromium and nickel (the last two elements represented in trace elements maps, respectively on the top and bottom right), due to the entry of new, hotter and more primitive magma into the Stromboli feeding system. Image by CM Petrone.
Photo 4 - The eruptive column formed above Stromboli during the paroxysm of 3 July 2019. Photo by G. De Astis.
Ph. 4 - The eruption column that formed above Stromboli during the 3 July 2019 paroxysm. Photo by G. De Astis.
