The 3 July 2019 paroxysm at Stromboli volcano (Italy): is Stromboli playing by new rules?

Lead Research Organisation: The Natural History Museum
Department Name: Earth Sciences

Abstract

On the afternoon of 3 July 2019, a violent explosive event (called paroxysm) affected the entire crater terrace of Stromboli volcano in Southern Italy, generating two pyroclastic flows that advanced for about 1 km across the sea beyond the coastline. The eruptive column rose for about 4 km above the summit and was accompanied by intense fall of scoriae and pumice, mostly around the village of Ginostra in the southwestern sector of the volcano, setting the vegetation on fire and causing one fatality and one injured person. The death toll could have been much higher, considering that during the summer months there are hundreds of tourists climbing the volcano every evening. In fact, on the afternoon of 3 July 2019 there were 230 people waiting to start their climb.

Stromboli is well-known as the lighthouse of the Mediterranean for its persistent "normal" Strombolian activity, consisting of low-energy explosions occurring every 10-20 minutes from multiple vents located in the crater area. This persistent activity is accompanied by lava flows at intervals of several years and, occasionally, is interrupted by discrete violent explosive events, such as the one that occurred on 3 July, which lasted several minutes, fed a km-long vertical column of gas, scoria and pumice that launched blocks up to 2-3 km from the source. In the last century there have been about 17 paroxysms with the strongest one, also associated with a tsunami, on 11 September 1930, and the most recent ones on 5 April 2003 and 15 March 2007.

Paroxysms are sudden, infrequent and highly damaging events that are very difficult to forecast. Previous work at Stromboli has shown that each of the last 4 paroxysms over 70 years of recorded eruptive history were preceded by lava effusion. In particular, the two most recent paroxysms in 2003 and 2007 occurred after the effusion of a similar cumulative volume of lava over a period of a few weeks to months preceding the large explosive events. These considerations have led to the current hypothesis that the volume of the effusive activity can be used to forecast future paroxysmal events. However, the 3 July 2019 did not play by this rule; it was preceded by very limited effusive activity only two minutes before the explosive event. At the same time, and rather untypical for the most recent activity of Stromboli, effusive activity started immediately after the explosive event, accompanied by intense explosive activity, and is still ongoing at the time of writing (early August 2019), raising concerns about the possibility of a second paroxysm.

It is clear that in order to enhance our ability to forecast such deadly events, it is crucial to understand their driving mechanisms. We propose to exploit this unique opportunity to capitalise on this unexpected event on 3 July 2019 through a detailed petrological and geochemical investigation of the eruptive products to unravel pre- and syn-eruptive magma ascent and degassing processes and their timescales, magma storage and crystallisation conditions as well as magma mixing processes and their timescales prior to eruption.

This is a unique opportunity to obtain, for the first time, crucial and novel information on the processes and timescales of magma ascent and degassing of such a disruptive event using the solid eruptive products that directly probe the underlying magma plumbing system. As the clock on the short-lived radionuclide 210Po (half-life = 138 days), which is one of our probes for determining the timescales of magma ascent and gas transfer, is already ticking, funding this proposal is time-critical.

Planned Impact

Volcanic eruptions fascinate and frighten at the same time. If an unexpected large deadly eruption occurs at a perceived "trustworthy" volcano, which also happens to be a renowned touristic place, such as Stromboli, the impact is even higher. During a large-scale eruptive event such as the one that occurred on 3 July 2019 at Stromboli, there are many stories to be told: personal (i.e., people living on Stromboli and the tourists visiting the island), official (i.e., local authorities), scientific (i.e., scientists monitoring the volcano) and hidden (i.e., what actually happens inside the volcano's underlying magmatic system). Working with local authorities, local communities and the many scientists monitoring the volcano, we will capitalise on our expertise to convey the findings from this study telling the hidden story, i.e., the magmatic perspective, of the 3 July 2019 paroxysm of the volcano.

We will engage with: 1) the local communities and civil authorities on Stromboli and the Aeolian Islands, via our personal contacts and experience (PI Petrone, CoI Gertisser, PPs Scarlato and Mollo have decadal experience working on Italian volcanoes); 2) the Italian Civil Protection via direct contact trough INGV (PP Scarlato), which is the reference scientific institution for geo-hazards of the Italian government; 3) the volcanological guides who regularly run touristic tours to the top of Stromboli volcano; (4) schools in the UK and Italy, via personal contacts of the PI, CoI and PPs, to inspire the next generation of scientists and to raise awareness of natural hazards; 5) National geological institutions and volcano observatories, via direct contact and the preferential access of INGV to the international network of volcano observatories and volcanic centres; 6) the general public, particularly those visiting the Natural History Museum (> 5 million a year).

We will engage the above-mentioned beneficiaries in different ways, from the more traditional, like direct meetings, public talks, social media, blog, TV and Radio interviews, to more focused workshops in schools. In fact, PI Petrone has established contacts with the William Perkin School in London, which has a strong scientific focus, to develop a long-term program of regular lectures and hands-on activities that will follow the progress of the project. CoI Gertisser runs learning and outreach activities using Keele's STARDOME (owned and managed by Higher Horizons+) allowing an IMAX-type movie experience for students on "Supervolcanoes". It can be brought into schools and can accommodate 25 pupils during a 30-minute session. We expect that this program can have long lasting impact promoting STEM subjects at schools in the UK.

The proposed project falls within the remit of NERC strategy addressing two societal challenges: 1) managing environmental change and 2) resilience to environmental hazard strands.

Publications

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Description Stromboli volcano (Southern Italy) shows characteristic persistent volcanic activity consisting of periodic discrete mild Strombolian explosions alternating with episodic lava effusions and more violents explosive events (parosysms), occuring at intervals of a few years. However, the two most recent paroxysms occurred at very short time interval, on 3 July and 28 August 2019, are challenging our understading of the most recent magma dynamics and related paroxysms.
Black scoriaceous lapilli and bombs, representing a degassed highly porphyritic (hp) magma are typically ejected during the normal Strombolian eruptions. Episodic paroxysms also erupt black scoriaceous bombs and spatters, variably mingled with a small volume of light pumices, representing a more mafic, hotter, volatile-rich magma with low phenocryst content (lp). These typical mingled hp-lp products, comprising plagioclase, clinopyroxene and minor olivine, were also erupted during the 2019 paroxysms. Clinopyroxene presents chemical heterogeneties similar to previously erupted products with diopsidic (Mg# 81-90) and augitic (Mg# 71-80) compositions. Diopsidic compositions are mostly recorded by rims and antecrystic cores, inherited from a mush region, and are markers of the more primitive, recharge lp-magmas. Augitic compositions are typical of clinopyroxenes cores representing the resident hp-magma.
The award is at an early stage by preliminary results suggests that clinopyroxenes indicate a magmatic system hotter (lp-magma 1160-1190 ºC; hp-magma 1140-1170 ºC) than that of 2003-2017 activity. The paucity of antecrysts and the prevalence of diopsidic rims are the main and significant textural differences compared with previous 2003-2017 eruptions. Timescales of mafic triggering events (1-39 days) are clearly recorded by the diopsidic rims in the 2019 light pumices and mingled products, contrary to previous paroxysms. All this suggests fast and continuos inputs of lp-magmas, triggering paroxysms at a very short time intervals, perhaps in a rejuvinated magmatic system where the crystal mush has been disrupted and partly reduced.
Exploitation Route Once the award is completed the results will be discuss with INGV, the Italian civil protection and the local community. In addition, we plan to progress further knowledge by submitting a NERC Standard grant.
Sectors Education,Environment,Government, Democracy and Justice,Culture, Heritage, Museums and Collections

 
Description The ward is still active, so it's really early stage but our preliminary results indicate that the magmatic system of Stromboli has significantly changed and this will have an important impact for forecasting future activity. Once the award is completed the results will be discuss with INGV, the Italian civil protection and the local community.
First Year Of Impact 2019
Sector Communities and Social Services/Policy,Education,Environment,Leisure Activities, including Sports, Recreation and Tourism,Government, Democracy and Justice,Culture, Heritage, Museums and Collections
Impact Types Cultural,Societal,Economic,Policy & public services

 
Description INGV Roma 
Organisation National Institute for Geophysics and Volcanology (INGV)
Country Italy 
Sector Public 
PI Contribution Provide mineralogical analysis via EPMA, BSE imagines via SEM, determine timescales for clinopyroxene from the 2019 paroxysmical eruptions of Stromboli volcano (Italy)
Collaborator Contribution Sample collections, provide experimental and analytical resources from the HPHT Laboratory of Experimental Volcanology and Geophysics in Rome (Italy).
Impact Conferences abstract and scientific manuscripts (see relevant sections)
Start Year 2019
 
Description Sapienza Universita di Roma 
Organisation Sapienza University of Rome
Country Italy 
Sector Academic/University 
PI Contribution Provide mineralogical analysis via EPMA, BSE imagines via SEM, determine timescales for clinopyroxene from the 2019 paroxysmical eruptions of Stromboli volcano (Italy)
Collaborator Contribution Provide scientific support to constrain the P-T-H2O conditions at which clinopyroxene growth before magma eruption and help to elucidate the ascent velocity of magma within the volcanic conduit by using intracrystal cation redistributions under the kinetic effects of magma dynamics.
Impact Conferences abstract and scientific manuscripts (see relevant sections)
Start Year 2019
 
Description University of Iowa 
Organisation University of Iowa
Department College of Liberal Arts and Sciences
Country United States 
Sector Academic/University 
PI Contribution Provide mineralogical analysis via EPMA, BSE imagines via SEM, determine timescales for clinopyroxene, CSD and chemical analysis of groundmass for the 2019 paroxysmical eruptions of Stromboli volcano (Italy)
Collaborator Contribution Analyze the samples for 232Th, and the standard suite of 238U-series nuclides. This would include multiple analyses of the volatile and short-lived nuclide 210Po (half-life = 138 days) to determine the activities of both 210Po and 210Pb (half-life = 22.3 years). These data will provide information on magma generation and differentiation processes over a broad range of time-scales, including processes occurring in the decades, years, and months leading up to the eruption.
Impact Conferences abstract and scientific manuscripts (see relevant sections)
Start Year 2019
 
Description Great Academy Ashton under Lyne - Stardome [Supervolcanoes] 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact One-day outreach event at Great Academy Ashton under Lyne, reaching 150 geography students (Y10) and their teachers. Ralf Gertisser delivered a "Geography and Earth science" careers talk, followed by a "Supervolcanoes" movie using Keele's Stardome, and an interactive session with information and volcanic rock specimens from Stromboli and other volcanoes.
Year(s) Of Engagement Activity 2019
URL https://www.keele.ac.uk/study/informationforschoolsandcolleges/activitiesforlearners/stardome/
 
Description Totally Awesome Humanities - Stardome [Supervolcanoes] 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact As part of a Higher Horizons event, a government-funded scheme that uses innovative outreach sessions to encourage young people to progress to higher education, at Keele University entitled "Totally Awesome Humanities", four sessions were held for groups of up to 25 students (mixture of Y9 & Y10) and their teachers from different schools in the Stoke-on-Trent area. In each of the one hour sessions, Ralf Gertisser delivered a "Supervolcanoes" movie using Keele's Stardome, followed by an interactive session with information, volcanic rock specimens and thin sections from Stromboli volcano and its paroxysmal eruption in 2019.
Year(s) Of Engagement Activity 2019
URL https://www.keele.ac.uk/study/informationforschoolsandcolleges/activitiesforlearners/stardome/
 
Description UCL Women in Earth Sciences 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact A talk at UCL earth Science Department for their Women in Earth Sciences Series - "Timing volcanic eruptions: deciphering minerals time-related information", 31 January 2020
Year(s) Of Engagement Activity 2019
 
Description West Sussex Geological Society 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact A public talk at West Sussex Geological Society - "Volcano psychology: understanding the eruptive clock at active volcanoes", 18 October 2019
Year(s) Of Engagement Activity 2019
URL http://www.wsgs.org.uk/1202_wsgs_002.htm
 
Description William Perkin High School 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact A talk at William Perkin High School in London - "Volcanoes" - 25 November 2019
Year(s) Of Engagement Activity 2019