AIV 2015 International School - "Volcanic Growth and landscape response: Volcanic processes and basin sedimentation"
"Volcanic growth and landscape response: Volcanic processes and basin sedimentation"
took place in Lipari, Aeolian Islands (Italy) from October 5th to 11th.
The school was a joint organization of the Italian Association of Vulcanology (AIV) and Italian Association for the study of the Quaternary (AIQUA), with the financial support of IAVCEI, and the kind hosting of the Regional Archaeological Museum of Lipari (thanks to the Director Dr. M.A. Mastelloni). The organizing and scientific committee was composed by Federico Lucchi (University of Bologna), Roberto Sulpizio (University of Bari), and Giovanni Zanchetta (University of Pisa), who also acted as fieldtrip leaders.
The school focused on the description of volcanic systems as the result of different geological and geomorphological processes. The competing phases of construction and dismantling were described in the light of eruptive and erosive processes. Both processes supply material for basin sedimentation, which was analyzed through primary and reworking deposition at local and regional scale. In addition, the role of deposition of volcanic ash over large areas was debated in the light of volcanic hazard and as a powerful tool for inter-archives correlations.
Fig. 1. Panoramic view of the islands of Lipari and Salina, and the peninsula of Vulcanello from the peak of La Fossa cone on Vulcano Island
The Aeolian Islands are a perfect location for the proposed topic (Fig. 1), due to a wide variety of emerged and submerged volcanoes characterized by effusive-explosive eruptions along with frequent volcano-instability events (i.e. lateral collapses) and volcano-tectonic activity (i.e. formation of calderas). The volcanic edifice dismantling dominated the basin sedimentation, with volcaniclastic deposition down to the Tyrrhenian abyssal plain. The widespread occurrence of marine terrace deposits testifies for changes in sea level occurred at various times since MIS5.
Fig. 2. The school group on top of the Fossa cone, Vulcano Island (a, photo courtesy of Susana Osorio), and during the poster session (b)
The school was attended by 25 young researchers (graduate students, PhDs, post-docs). They are from: Italy (11), Philippines (3), Mexico (3), Brazil (2), Singapore (1), Spain (1), England (1), France (1), Republic of Dominica (1), and Germany (1), with different experiences and skills in the fields of Volcanology and Quaternary sciences. The participants had the opportunity to present their researches and to share ideas in an enjoyable poster session (Fig. 2).
The lectures were accompanied by three days of fieldtrips, focused on various aspects of the geology of the Aeolian volcanoes, promoting discussions among all the participants. The program of both lectures and fieldtrips was accomplished at 90%, in spite of adverse weather conditions (as it can happen in islands) that forced the organizers to changes of schedule.
The first day of the school (October 6th) was entirely devoted to class lectures: 1) Eruptive activity and volcano building (Prof. P. Dellino, University of Bari); 2) Volcanic deposits (Prof. R. Sulpizio, University of Bari); 3) Subaerial volcaniclastic deposits (Prof. G. Zanchetta, University of Pisa); 4) Deformations of the Aeolian Islands from geodetic and archaeological data: implications on recent volcanism, sea levels and coastline changes (Prof. M. Anzidei, INGV Rome); 5) Geological fieldwork in volcanic areas (Prof. F. Lucchi, University of Bologna). These lectures provided the a basic knowledge of the most important features of volcanic activity and related deposits, with special attention to the fieldwork in volcanic areas. The field excursion to the islands of Vulcano and Lipari, scheduled for the following day, was introduced by Roberto Sulpizio and Federico Lucchi.
Fig. 3. Summit crater of La Fossa cone on Vulcano Island feeding the 1888-90 vulcanian activity (a) and the hydrothermal field that characterizes its present state of quiescence (b)
The second day (October 7th) was passed in the field at Vulcano Island. The main topics of the fieldtrip were the deposits produced by the typical vulcanian explosive activity, the present summit hydrothermal fieldand and the dynamics of sedimentation and erosion in an active volcano (Fig. 3). Moreover, the role played by the La Fossa caldera in conditioning the localization of the active vents and the distribution of volcanic products were investigated. These field activities promoted discussions about the volcanic significance of vulcanian eruptions, the dynamics of deposition and erosion along longitudinal drainage systems around active volcanoes, and the factors triggering caldera formation. In the afternoon, on the way back to Lipari, it was scheduled a short tour by boat along the western coast of Lipari island aimed at describing the Late Quaternary marine terraces interlayered within the volcanic succession. Unfortunately, this part of the fieldtrip was skipped due to bad sea conditions.
Fig. 4. Fieldwork on the pyroclastic deposits of the Monte Guardia succession along the valley of Valle Muria on Lipari Island
The morning of third day (October 8th) was devoted to class lectures: 1) Volcanology and archeology (Prof. M. Di Vito, INGV Naples); 2) Volcanic activity and basin sedimentation (Prof. C. Romagnoli, University of Bologna); 3) Environmental dispersion of volcanic ash (Prof. A. Costa, INGV Bologna); 4) Tephrostratigraphy of Central Mediterranean (Prof. P. Albert, Royal Holloway University London). These lectures gave the participants information about the characteristics of basin sedimentation around the Aeolian Islands, including the widespread dispersal of pyroclastic deposits and their importance for tephrostratigraphic correlations. The afternoon was spent in the field along a footpath through the southern sector of Lipari island, with a particular focus on the stratigraphic relationships between pyroclastic deposits, domes and Brown Tuffs originated from the adjacent Vulcano Island exposed along the valley of Valle Muria. A special attention was dedicated to the approach to description and interpretation of pyroclastic deposits from fallout and pyroclastic density currents, and their main features (sorting, components, stratification structures, bomb sags, etc.) (Fig. 4). Moreover, discussion was promoted on the factors controlling the transition of eruptive style from explosive to effusive, the influence of the pre-depositional topography on the distribution and depositional features of PDCs, and the main criteria of correlation of tephra layers.
Fig. 5. A view of the Basiluzzo dome offshore the Panarea Island, with Stromboli in the background (a), and the Sciara del Fuoco collapse structure along the NW flank of Stromboli (b)
The morning of the fourth day (October 9th) had class lectures: 1) Tephras in paleoclimatology (Prof. G. Zanchetta, University of Pisa); 2) The use of stratigraphic data for the mitigation of hazard (Prof. R. Sulpizio, University of Bari). They were aimed at providing the basic information on the use of tephras pyroclastic deposits in paleoclimatic studies and for the assessment of volcanic hazard and risk through some examples applied to Vesuvius. Later, Federico Lucchi introduced the field excursion to Panarea and Stromboli scheduled for the afternoon. This was the most important change to the program due to the adverse weather conditions. The weather forecast referred to two-three days of rough sea that could cause the blockage of naval transport between the islands, leading to the ominous prospect that the school participants could get stuck on the Stromboli island losing their flight coincidences to back home. Therefore, the organizers decided to remove the field excursion to the Stromboli summit craters and they replaced it with a tour by boat across the islands of Panarea and Stromboli. A few stops along the coasts of Panarea allowed observation of the typical morphology of an andesitic dome-field, with a particular focus on the internal structure of the endogenous Basiluzzo lava dome (Fig. 5). Good exposures of marine terraces were seen along the southern coast of Panarea, documenting the complex relationships between volcanism, crustal uplift and Late Quaternary sea-level fluctuations during the building up of a volcanic island. After that, we headed on toward Stromboli with the possibility of being stationed for some time in front of the Sciara del Fuoco collapse (fig. 5). This is a very spectacular example of the building up of a volcano through phases of eruptive activity interrupted by recurrent lateral collapses and flank erosion. We observed closely the 2014 lava flow and lava delta, and we were lucky enough for observing some strombolian explosions from the active craters located near the headwall of the collapse.
The fifth day (October 10th) was dedicated to a fieldtrip on the Lipari Island, organized in a number of stops illustrating different features of the stratigraphy and volcanic evolution of Lipari. Special attention was given to the observation and discussion of the main features of the obsidian lava flow of Rocche Rosse, emplaced during to the most recent activity of Lipari Island. Discussion was focused on the features that can favour an increased mobility of viscous lava flows. Unique hydrothermal alterations and lacustrine deposits consisting of alternating primary pyroclastic layers and chert horizons were observed on the western coast of Lipari. Finally, we had a panoramic view on the southern coast of Lipari with Vulcano in the background discussing about the NNW–SSE regional tectonic control on the development of the Aeolian central sector. In the afternoon, most of the participants were forced to leave in advance the Aeolians in order to avoid the sea storm predicted for the day after, originally scheduled for the departure from Lipari.
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