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This research project concerns the study, analysis and dating of obsidian flows on the island of Lipari, in relation to the population of the Aeolian Islands, during the Neolithic period.The collection, processing and diffusion of Lipari obsidian characterise the Neolithic population of Lipari and the entire Mediterranean. By improving the knowledge of supply methods in the territory, it will be possible to formulate hypotheses on the chronology of the sources, the ways of collecting the raw material and on the mobility of the Neolithic communities in the Aeolian Islands. The scientific research is divided into two main topics: the first concerns the analytical and methodological aspects of archaeological and geological studies of Lipari obsidian; the second, the formation of obsidian at Lipari, their sources and lithological characteristics. Throughout the duration of this study we will perform new age determinations of Neolithic obsidian artefacts and geological samples, directly with the method of fission track, and indirectly dating paleo soils using the radiocarbon method.

Pyrometamorphism is the highest temperature end-member of the sanidinite facies (high-temperature, low-pressure contact metamorphism) and comprises both subsolidus and partial melting reactions which may locally lead to cryptocrystalline-glassy rocks (i.e., porcellanites and buchites). A wide range of pyrometamorphic ejecta, with different protoliths from Stromboli volcano, have been investigated over the last two decades. Among these, a heterogeneous (composite) glassy sample (B1) containing intimately mingled porcellanite and buchite lithotypes was selected to be studied through new FESEM–EDX and QEMSCAN™ mineral mapping investigations, coupled with the already available bulk rock composition data. This xenolith was chosen because of the unique and intriguing presence of abundant Cu–Fe sulphide globules within the buchite glass in contrast with the well-known general absence of sulphides in Stromboli basalts or their subvolcanic counterparts (dolerites) due to the oxygen fugacity of NNO + 0.5–NNO + 1 (or slightly lower) during magma crystallization. The investigated sample was ejected during the Stromboli paroxysm of 5 April 2003 when low porphyritic (LP) and high porphyritic (HP) basalts were erupted together. Both types of magmas are present as coatings of the porcellanite–buchite sample and were responsible for the last syn-eruptive xenoliths’s rim made of a thin crystalline-glassy selvage. The complex petrogenetic history of the B1 pyrometamorphic xenolith is tentatively explained in the framework of the shallow subvolcanic processes and vent system dynamics occurred shortly before (January–March 2003) the 5 April 2003 paroxysm. A multistep petrogenesis is proposed to account for the unique occurrence of sulphide globules in this composite pyrometamorphic xenolith. The initial stage is the pyrometamorphism of an already hydrothermally leached extrusive/subvolcanic vent system wall rock within the shallow volcano edifice. Successively, fragments of this wall rock were subject to further heating by continuous gas flux and interaction with Stromboli HP basalt at temperatures above 1000 °C to partially melt the xenolith. This is an open system process involving continuous exchange of volatile components between the gas flux and the evolving silicate melt. It is suggested that the reaction of plagioclase and ferromagnesian phenocrysts with SO2 and HCl from the volcanic gas during diffusion into the melt led to the formation of molecular CaCl in the melt, which then was released to the general gas flux. Sulphide formation is the consequence of the reaction of HCl dissolved into the melt from the gas phase, resulting in the release of H2 into the melt and lowering of fO2 driving reduction of the dissolved SO2.

Vulcano is part of the Aeolian volcanic arc in the southern Tyrrhenian Sea. Its products were emplaced through multiple episodes of edifice building and collapse since about 120 ka B.P. to present. A major discontinuity in the activity occurred after about 28 ka, while the focus of volcanism moved from SE to NW. The older products are basalts to shoshonites, and have lower K2O than the younger ones, shoshonites to rhyolites. Between these two groups, Lentia latites-rhyolites, Spiaggia Lunga basalts, and Quadrara shoshonite-trachytes, erupted along the western side of Vulcano Island. The Spiaggia Lunga basalts (i) are the most primitive magmas erupted at Vulcano after 28 ka (ii) mark the change between older and younger phases, and (iii) overlap geochemically with a monzogabbroic intrusion of similar age. This work focuses on the Spiaggia Lunga products, discussed within a large dataset of geochemical and radiogenic isotope analyses on the entire Vulcano sequence. Older products have more primitive geochemical and isotope characteristics, and lower incompatible element contents, than younger ones. The Spiaggia Lunga basalts exhibit intermediate geochemical characteristics between the older and the younger groups, and can likely be regarded as a third magmatic phase, which represents a distinct mantle reservoir active during the magmatic history of Vulcano. Significant variations of Sr, Nd, and Pb isotope ratios, and isotopic disequilibrium between phenocrysts and groundmass, are present among the Vulcano products. This variability suggests crustal assimilation in shallow-level magma chambers, which also accounts for the formation of evolved products by combined assimilation and fractional crystallization, particularly in the younger series. Considering only the mafic products, incompatible element patterns with high LILE/HFSE and enriched signatures of Sr, Nd, and Pb isotope ratios, indicate enriched mantle sources. Besides, chemical and isotope variability among older, younger, and Spiaggia Lunga mafic rocks, suggests an origin from geochemically diverse primary melts, derived from distinct mantle reservoirs. Their parent magmas, based on geochemical and isotope patterns, were from both MORB- and OIB-type mantle sources, subject to variable degrees of metasomatism by subducted sediments.

An integrated petrological and geochemical study on plagioclase crystals erupted at Vulcano Island (Aeolian Islands, Southern Italy) over the past 1000 years allowed us to draw a detailed model of the internal structure of the volcanic system, in which modes of magma interaction and timescales of storage at crustal depth are shown. The integration of compositional, textural and temporal record preserved in plagioclase crystals provides evidence for an articulated plumbing system constituted by several reservoirs connected at the crust-mantle boundary. Here, a basaltic-shoshonitic magma resides and is thought to feed the shallow magma reservoir of both La Fossa and Vulcanello centers, finally triggering eruptions throughout injections from depth. Textural and micro-compositional data on plagioclase crystals suggest the presence of three main magma levels located between ca. 17 and 2 km of depth beneath La Fossa Cone, which were intermittently reactivated over the whole period of activity considered. Plagioclase textures and compositional zoning indicate that the shallow (

In the Central Mediterranean region, the production of chemically diverse volcanic products (e.g., those from Mt. Etna and the Aeolian Islands archipelago) testifies to the complexity of the tectonic and geodynamic setting. Despite the large number of studies that have focused on this area, the relationships among volcanism, tectonics, magma ascent, and geodynamic processes remain poorly understood. We present a tomographic inversion of P-wave velocity using active and passive sources. Seismic signals were recorded using both temporary on-land and ocean bottom seismometers and data from a permanent local seismic network consisting of 267 seismic stations. Active seismic signals were generated using air gun shots mounted on the Spanish Oceanographic Vessel 'Sarmiento de Gamboa'. Passive seismic sources were obtained from 452 local earthquakes recorded over a 4-month period. In total, 184,797 active P-phase and 11,802 passive P-phase first arrivals were inverted to provide three different velocity models. Our results include the first crustal seismic active tomography for the northern Sicily area, including the Peloritan-southern Calabria region and both the Mt. Etna and Aeolian volcanic environments. The tomographic images provide a detailed and complete regional seismotectonic framework and highlight a spatially heterogeneous tectonic regime, which is consistent with and extends the findings of previous models. One of our most significant results was a tomographic map extending to 14 km depth showing a discontinuity striking roughly NW-SE, extending from the Gulf of Patti to the Ionian Sea, south-east of Capo Taormina, corresponding to the Aeolian-Tindari-Letojanni fault system, a regional deformation belt. Moreover, for the first time, we observed a high-velocity anomaly located in the south-eastern sector of the Mt. Etna region, offshore of the Timpe area, which is compatible with the plumbing system of an ancient shield volcano located offshore of Mt. Etna.

Emissivity and reflectance spectra have been investigated on two series of silicate glasses, having compositions belonging to alkaline and subalkaline series, covering the most common terrestrial igneous rocks. Glasses were synthesized starting from natural end-members outcropping at Vulcano Island (Aeolian Islands, Italy) and on Snake River Plain (USA). Results show that the shift of the spectra, by taking Christiansen feature (CF) as a reference point, is correlated with SiO2 content, the SCFM factor and/or the degree of polymerization state via the NBO/T and temperature. The more evolved is the composition, the more polymerized the structure, the shorter the wavelength at which CF is observable. CF shift is also dependent on temperature. The shape of the spectra discriminates alkaline character, and it is related to the evolution of Qn structural units. Vulcano alkaline series show larger amount of Q4 and Q3 species even for mafic samples compared to the subalkaline Snake River Plain series. Our results provide new and robust insights for the geochemical characterization of volcanic rocks by remote sensing, with the outlook to infer origin of magmas both on Earth as well as on terrestrial planets or rocky bodies, from emissivity and reflectance spectra.

We present and discuss temperatures, major and trace element gas geochemistry, radiogenic isotopes (Pb, Sr) and the first Zn isotope data of fumarole condensates and altered rocks from the Vulcano fumarolic field. The fumaroles of the La Fossa cone, sampled on 5th May 2015, have temperatures ranging between 233 and 427 °C. They plot compositionally on the mixing trend between the magmatic and hydrothermal end-members defined by previous studies, but are strongly displaced towards the hydrothermal component. Correlations of radiogenic (Sr, Pb) and stable isotopes of Zn with δ13CCO2 and several trace elements of the fumarolic acid condensates support mixing between the above mentioned distinct (magmatic and hydrothermal) fluids. The magmatic end-member has a less radiogenic Sr (87Sr/86Sr ~0.7045) and heavier Zn isotope composition (δ66Zn ~0.3‰). The hydrothermal fluid end-member has a more radiogenic 87Sr/86Sr signature (>0.7055), which could be due to leaching of radiogenic Sr from the crystalline basement rocks or reflect seawater Sr. It is also characterized by lighter Zn isotope composition (δ66Zn < −0.3), most likely reflecting equilibrium fractionation of Zn isotopes during precipitation of sphalerite (ZnS) from the hydrothermal fluid. Nonetheless, some scatter in the correlation trends suggests either the involvement of additional (subordinate) source(s) or temporal variations in isotopic and chemical compositions of the two above end-members. Pb isotope compositions of the fumaroles sampled in this study show a shift towards less radiogenic values compared to pre-2001 fumaroles. This could indicate either a change in the hydrothermal circulation pattern (leading to leaching of rocks with different isotopic compositions) or the involvement of a new, isotopically distinct, magmatic fluid. The alteration zones around the fumarole vents are also characterized by systematic correlations of Pb and Zn isotopes with major and trace elements. We interpret these as the result of the addition onto the substratum volcanic rock of Pb and Zn from the fumaroles. Zn isotope signatures of the alteration zones are significantly heavier than those of the corresponding fumaroles (δ66Zn = 0.3–1.6) probably due to equilibrium fractionation occurring during sphalerite precipitation at the vent discharge.

The recent high-resolution multibeam bathymetry surveys around Lipari Island allowed to evidence several submarine canyons, whose head often cut back up to very shallow water and at a few tens of meters far from the coast. These canyons are mainly located in the eastern and southern side of the island and are characterized by an ongoing retrogressive (landward) erosion, that also controlled the shape and the evolution of the coastline. The canyon heads are formed by minor slide scars. By coupling slide scar morphometry and simple numerical model we have been able to roughly estimate the potential tsunami wave amplitudes generated by related slope failures. Moreover, the retrogressive erosion of canyon heads can be claimed as a cause of the enhanced subsidence reported in the last few thousand years in the eastern part of Lipari, where the main villages are located. Based on these evidence, we propose a first assessment of the coastal hazard due to marine retrogressive activity in the largest and most densely populated island of the Aeolian Archipelago.

Archaeological excavations in the S-F area of Piani della Corona settlement have affected a portion of 2200 m2 of a large plateau (490 m asl). The researches, conducted between 2007 and 2008 by the Superintendence of the Museo Preistorico Etnografico “L. Pigorini” with the Archaeological Superintendence of Calabria, have revealed traces of a large village from the EBA. Before settling in the EBA, human groups belonging Recent Neolithic frequented the plateau. Two burials located near the Bronze Age ditch belong to this period, and there are also sporadic ceramic fragments recovered from the huts. The importance of Piani della Corona is mainly due to its strategic location, serving as a bridge between Calabria, Sicily and the Aeolian Islands, as proven by the archaeological record. A very important role was provided by the obsidian industry, dated after the most distinctive archaeological ceramics class, to the EBA. Out of the 238 obsidian tools found in the S-F area (blades, cores and amorphous splinters), 88 artifacts were analyzed by pXRF. Their chemical determination made it possible to clarify the procurement dynamics and exchange routes with the Aeolian Islands for the EBA, integrating new data in an on-going research.

An update of the surface ground deformation field over the Lipari-Vulcano complex has been provided by analyzing all the available GPS observations collected in the last two decades. The geodetic velocity field, referred to a fixed Eurasian frame, shows a remarkable negative velocity gradient between the southernmost stations (velocity values of ∼9.0 mm/yr) and the northernmost ones, resulting in a N–S contraction of ∼4.5 mm/yr. In addition, all the GPS stations show subsidence with rates decreasing from the northernmost stations (∼ -10.0 mm/yr) to the southernmost ones (∼ -4.8 mm/yr). Modelling of geodetic data demonstrates that the observed surface deformation field results from the joint contribution of regional (tectonic) and local (magmatic) sources. Such a dataset is unable to uniquely constrain the magmatic source. Indeed, the three performed models (M1, M2 and M3) produce statistically equivalent deformation sources. The source modeled in M1 is spatially coincident with that of M3, and both are located beneath the Vulcanello cone at depth of ∼4 km bsl. Conversely, the source modeled in M2 is placed at depth of 0.76 km bsl beneath the northern rim of the La Fossa crater. Integration of these results with geochemical and petrological data already available from literature suggests, however, that the M1≡M3 source placed beneath the Vulcanello cone should be the preferred model.

Volcanic ash (1000 analyses) provides a basis for proximal-distal and distal-distal tephra correlations. Tephra deposits from the different Aeolian Islands are geochemically diverse; with some individual eruptions showing diagnostic geochemical heterogeneity recognised both stratigraphically and/or spatially. Major element glass analyses reveal that Vulcano (0-21ka) and Stromboli (4-13ka) have erupted potassic (shoshonitic and K-series) tephra with broadly overlapping compositions, but data presented here demonstrates that their eruptive products can be distinguished using either TiO2 contents or their HFSE/Th ratios. Whilst individual volcanic sources often produce successive tephra deposits with near identical major and minor element compositions through time (i.e., Lipari, Vulcano), trace element glass data can help to decipher successive eruptions. Changes in LREE and Th concentrations of volcanic glasses erupted spanning approximately the last 50ka greatly enhance the potential to discriminate successive eruptive units on Lipari. The new proximal glass database has been used to verify new (Ionian Sea; core M25/4-12) and existing distal occurrences of Aeolian Island derived tephra enabling the reassessments of past ash dispersals. Finally, proximal and distal data have been used to establish an integrated proximal-distal eruptive event stratigraphy for the Aeolian Islands.

Ammonium- and Fe(II)-rich fluid flows, known from deep-sea hydrothermal systems, have been extensively studied in the last decades and are considered as sites with high microbial diversity and activity. Their shallow-submarine counterparts, despite their easier accessibility, have so far been under-investigated, and as a consequence, much less is known about microbial communities inhabiting these ecosystems. A field of shallow expulsion of hydrothermal fluids has been discovered at depths of 170-400 meters off the base of the Basiluzzo Islet (Aeolian Volcanic Archipelago, Southern Tyrrhenian Sea). This area consists predominantly of both actively diffusing and inactive 1-3 meters-high structures in the form of vertical pinnacles, steeples and mounds covered by a thick orange to brown crust deposits hosting rich benthic fauna. Integrated morphological, mineralogical, and geochemical analyses revealed that, above all, these crusts are formed by ferrihydrite-type Fe3+ oxyhydroxides. Two cruises in 2013 allowed us to monitor and sampled this novel ecosystem, certainly interesting in terms of shallow-water iron-rich site. The main objective of this work was to characterize the composition of extant communities of iron microbial mats in relation to the environmental setting and the observed patterns of macrofaunal colonization. We demonstrated that iron-rich deposits contain complex and stratified microbial communities with a high proportion of prokaryotes akin to ammonium- and iron-oxidizing chemoautotrophs, belonging to Thaumarchaeota, Nitrospira, and Zetaproteobacteria. Colonizers of iron-rich mounds, while composed of the common macrobenthic grazers, predators, filter-feeders, and tube-dwellers with no representatives of vent endemic fauna, differed from the surrounding populations. Thus, it is very likely that reduced electron donors (Fe2+ and NH4+ ) are important energy sources in supporting primary production in microbial mats, which form a habitat-specific trophic base of the whole Basiluzzo hydrothermal ecosystem, including macrobenthic fauna.

The Aeolian Islands are an arcuate chain of submarine seamounts and volcanic islands, lying just north of Sicily in southern Italy. The second largest of the islands, Salina, exhibits a wide range of compositional variation in its erupted products, from basaltic lavas to rhyolitic pumice. The Monte dei Porri eruptions occurred between 60 ka and 30 ka, following a period of approximately 60,000 years of repose. The bulk rock composition of the Monte dei Porri products range from basaltic-andesite scoria to andesitic pumice in the Grey Porri Tuff (GPT), with the Monte dei Porri lavas having basaltic-andesite compositions. The typical mineral assemblage of the GPT is calcic plagioclase, clinopyroxene (augite), olivine (Fo72−84) and orthopyroxene (enstatite) ± amphibole and Ti-Fe oxides. The lava units show a similar mineral assemblage, but contain lower Fo olivines (Fo57−78). The lava units also contain numerous glomerocrysts, including an unusual variety that contains quartz, K-feldspar and mica. Melt inclusions (MI) are ubiquitous in all mineral phases from all units of the Monte dei Porri eruptions; however, only data from olivine-hosted MI in the GPT are reported here. Compositions of MI in the GPT are typically basaltic (average SiO2 of 49.8 wt %) in the pumices and basaltic-andesite (average SiO2 of 55.6 wt %) in the scoriae and show a bimodal distribution in most compositional discrimination plots. The compositions of most of the MI in the scoriae overlap with bulk rock compositions of the lavas. Petrological and geochemical evidence suggest that mixing of one or more magmas and/or crustal assimilation played a role in the evolution of the Monte dei Porri magmatic system, especially the GPT. Analyses of the more evolved mineral phases are required to better constrain the evolution of the magma.

Lipari island belongs to the Aeolian archipelago, located in the Southern Tyrrhenian Sea (Italy), which is one of the most active volcanic areas of the Mediterranean basin. Although this region has been settled since prehistory, only during Roman times were coastal installations built in these islands. In this study, we present and discuss data on the relative sea level change estimated from a submerged pier of Roman age dated 2100 ± 100 BP. This structure, about 140 × 60 m, is located along the coast of Marina Lunga, corresponding to the present location of the main harbor of Lipari island. This pier, which was accidentally discovered in 2008 during preliminary excavations for the construction of a new pier, is a valuable indicator of relative sea level changes and vertical land movements. Its top surface is presently located at −9.1 ± 0.05 m, while the foundations at the outer end of the pier are at −11.6 ± 0.05 m, above a shoreline placed at −13.0 ± 0.05 m. We studied this site through direct archaeological investigations and ultra-high resolution multibeam bathymetry. The current submergence of this pier can be explained by the cumulative effect of the relative sea level changes caused by the regional glacio-hydro-isostatic signal, active since the end of the last glacial maximum, and the local volcano-tectonic land subsidence. From our investigations, a relative sea level change at 12.3 ± 0.7 m with a subsidence rate at 5.79 ± 0.01 mm y −1 and an average value of volcano-tectonic contribution at 5.17 ± 0.01 m y −1 for the last 2100 ± 100 years BP, is estimated from comparison against the latest predicted sea level model for the Southern Tyrrhenian Sea. These rates of relative sea level change led to the disuse of the harbor after around the fourth century AD, in agreement with archaeological interpretations. Our results provide new insights on the recent evolution of this active volcanic area.

Since the early 1970s, geodetic networks became a most important tool to monitor the present day deformations of the volcanic arc of the Aeolian Islands. The first benchmarks were installed in this region at Lipari and Vulcano Islands and the number of GPS benchmarks increased in time since the early ’90s. These networks were periodically surveyed in the frame of national and international geodynamic projects and for Civil Protection programs devoted to the mitigation of the volcanic hazard. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) played a fundamental role in the realization and periodical reoccupation of these networks, with the goal to investigate the tectonic and volcanic processes, still active in this crucial area of the central Mediterranean. An updated GPS velocity map for this region, both for the horizontal and vertical component of land motion, with details for Lipari, Vulcano and Panarea Islands, is provided in this paper. The presented GPS velocity field also includes a set of additional discrete stations located in northern Sicily and Calabria together with data from the available CGPS networks active in southern Italy. Here we show the results from eighteen years of repeated GPS surveys performed in this region in the time span 1995-2013 and the open access AINET-GPS data archive, now freely available for the scientific community. Data will support scientific research and hopefully improve the assessment of volcanic and seismic hazard in this region.

Very high resolution bathymetric map obtained through multibeam echo-sounders data are crucial to generate accurate Digital Terrain Models from which the morphological setting of active volcanic areas can be analyzed in detail. Here we show and discuss the main results from the first multibeam bathymetric survey performed in shallow-waters around the island of Lipari, the largest and the most densely populated of the Aeolian Islands (southern Italy). Data have been collected in the depth range of 0.1-150 m and complete the already existent high-resolution multibeam bathymetry realized between 100 and 1300 m water depth. The new ultra-high resolution bathymetric maps at 0.1-0.5 m provide new insights on the shallow seafloor of Lipari, allowing to detail a large spectrum of volcanic, erosive-depositional and anthropic features. Moreover, the presented data allow outlining the recent morphological evolution of the shallow coastal sector of this active volcanic island, indicating the presence of potential geo-hazard factors in shallow waters.

Over the last ~267 ky, the island of Lipari has erupted magmas ranging in compositions from basaltic andesites to rhyolites, with a notable compositional gap in the dacite field. Bulk geochemical and isotopic compositions of the volcanic succession, in conjunction with major and trace elemental compositions of minerals, indicate that the rhyolites were dominantly generated via crystal fractionation processes, with subordinate assimilation. Radiogenic (Sr, Nd, and Pb) and stable (O) isotopes independently suggest ≤30 % of crustal contamination with the majority of it occurring in mafic compositions, likely relatively deep in the system. Within the rhyolites, crystal-rich, K2O-rich enclaves are common. In contrast to previous interpretations, we suggest that these enclaves represent partial melting, remobilization and eruption of cumulate fragments left-over from rhyolite melt extraction. Cumulate melting and remobilization is supported by the presence of (1) resorbed, low-temperature minerals (biotite and sanidine), providing the potassic signature to these clasts, (2) reacted Fo-rich olivine, marking the presence of mafic recharge, (3) An38–21 plagioclase, filling the gap in feldspar composition between the andesites and the rhyolites and (4) strong enrichment in Sr and Ba in plagioclase and sanidine, suggesting crystallization from a locally enriched melt. Based on Sr-melt partitioning, the high-Sr plagioclase would require ~2300 ppm Sr in the melt, a value far in excess of Sr contents in Lipari and Vulcano magmas (50–1532 ppm) but consistent with melting of a feldspar-rich cumulate. Due to the presence of similar crystal-rich enclaves within the rhyolites from Vulcano, we propose that the eruption of remobilized cumulates associated with high-SiO2 rhyolites may be a common process at the Aeolian volcanoes, as already attested for a variety of volcanic systems around the world., Contributions to Mineralogy and Petrology, 170 (5-6), ISSN:0010-7999, ISSN:1432-0967

Effusive eruptions are explained as the mechanism by which volcanoes restore the equilibrium perturbed by magma rising in a chamber deep in the crust. Seismic, ground deformation and topographic measurements are compared with effusion rate during the 2007 Stromboli eruption, drawing an eruptive scenario that shifts our attention from the interior of the crust to the surface. The eruption is modelled as a gravity-driven drainage of magma stored in the volcanic edifice with a minor contribution of magma supplied at a steady rate from a deep reservoir. Here we show that the discharge rate can be predicted by the contraction of the volcano edifice and that the very-long-period seismicity migrates downwards, tracking the residual volume of magma in the shallow reservoir. Gravity-driven magma discharge dynamics explain the initially high discharge rates observed during eruptive crises and greatly influence our ability to predict the evolution of effusive eruptions.

La Fossa Caldera (LFC) on Vulcano island, in the Aeolian archipelago (Italy), is a multi-collapse caldera whose north-eastern part lies underwater. Through the integration of marine geophysical surveys and sampling carried out in the last decade, its submarine extension and offshore areas have been reconstructed in unprecedented detail. Strong erosive processes breached the submarine portion of LFC and gradually dismantled the caldera rims and infill, leading to the emplacement of a wide volcaniclastic fan from the base of LFC down to over 1000 m. The bathy-morphologic setting, seismoacoustic facies and analyses of sediment samples from the fan, together with volumetric considerations, suggest that this feature is the pathway/deposit of submarine unconfined gravity flows and turbidity currents deriving from the gradual dismantling of LFC. Submarine erosive processes are still active and the progressive erosion of the northern caldera sector threatens the stability of the active La Fossa Cone and the nearby coastal settlements. (C) 2012 Elsevier B.V. All rights reserved.

Submarine portions of Stromboli volcano account for about 98% of the whole extent of the volcanic edifice and are mostly covered by volcaniclastic sediments that made up a modern volcaniclastic apron. The architecture and main sedimentary processes acting within the apron are depicted through the integration of geophysical evidence (multibeam, long-range side scan sonar and seismic data) and seafloor sampling. The apron shows, on the whole, a large variability both across and along slope of morphologies and deposits related to mass-wasting and reworking processes, passing into areas covered by hemipelagic sedimentation. A large spectrum of erosive-depositional features was recognized on the surface of the apron. On shallower areas (i.e. submerged shelves, shore platforms and depositional terraces), submarine features related to wave action and sea-level fluctuations are present; they mainly act as temporary storing and reworking areas for volcaniclastic material derived from subaerial portions. Unconfined cohesionless inertial flows commonly dominate the upper slope, where gradients are very high (up to 35°) and grain-to-grain and grain-to-bed collisions are favoured within the flows. These flows tend to evolve into turbidity currents on the lower slope, in response to a marked decrease of slope gradients below ~ 8°, generating various erosive-depositional features, such as erosive furrows, troughs, channel-levee features and coarse-grained sediment waves. The most active area of the apron lies offshore Sciara del Fuoco (on the NW flank), where a large amount of coarse-grained volcaniclastic material, derived by the persistent Strombolian activity, is collected and deposited by means of high- and low-density turbidity currents on the lower slope down to 2600 m bsl, more than 20 km far from the island. Conversely, other areas are mostly dominated by deposition via settling of suspended sediments, related both to hemipelagic sedimentation and to the dispersion of fine tephras by the prevailing wind and marine currents. Such processes interfinger and overlie in space and time, giving rise to a very complex morpho-sedimentary facies distribution. However, the structural bilateral symmetry of Stromboli volcano allows defining distinct morpho-sedimentary zones, where one (or more) type of processes dominates, and related different stratal architecture of the apron. The unbuttressed portions of the island (NW and SE) are characterized by the emplacement of wide and thick debris avalanche deposits (volume in the order of 1-2 km3 for each event) related to large-scale sector collapses, representing the most important and efficient mass-wasting processes making up the apron. Such deposits are embedded within different volcaniclastic sequences and can be eroded or exhumed by successive gravity flows. The result is a highly complex (both spatially and vertically) succession of facies, where it is often difficult to depict an arranged series of processes. Conversely, on buttressed flanks (SW and NE) a more ordered evolution of processes and deposits making up the apron is observed, giving rise to a less complex apron architecture. © 2010 Elsevier B.V. All rights reserved.

Geological mapping of the island of Lipari at a 1:10,000 scale is performed by adopting a stratigraphic approach based on the integrated use of lithostratigraphic units, lithosomes, and unconformity-bounded units (UBU). This approach allows the geological peculiarity of this volcanic area to be reproduced through documenting and interpreting the different rock types (using lithostratigraphic units), and defining the geometry of rock bodies (using lithosomes), or highlighting unconformities in the volcano-sedimentary architecture (using UBUs). In particular, by concentrating on accurate tephrostratigraphy and deposits formed during periods of prolonged volcanic quiescence (e.g. marine deposits and epiclastic products), UBUs provide the main stratigraphic constraints at regional level. Two first-order unconformities (UI and UII), represented by surfaces of erosion bounding marine deposits emplaced during marine oxygen-isotope stage (MIS) 5, can be correlated across most of the Aeolian archipelago. Furthermore, four second-order and seven third-order unconformities represented by erosion and non-deposition surfaces formed during main periods of dormancy 2 or minor sea-level fluctuations of MIS 5 are introduced. The reconstructed unconformitybounded stratigraphy, together with other rock-stratigraphic units, provides an effective reconstruction of the geological evolution of Lipari, ranging between ca. 220 ka and the present time, as the result of the interplay between volcanic activity of local and external provenance, sea-level fluctuations, and regional fault systems. In this framework, Lipari’s eruptive history encompasses five successive eruptive epochs characterized by distinctive centres of eruption (eastwards shifting), eruption type (from mainly strombolian to hydromagmatic), and chemical composition (from calcalkaline basalt-andesite to high-K calcalkaline rhyolite).

Quartz-rich xenoliths in lavas (basalts to andesites; 90-30 ka) from Alicudi contain abundant melt and fluid inclusions. Two generations of CO2-rich fluid inclusions are present in quartz-rich xenolith grains: early (Type I) inclusions related to partial melting of the host xenoliths, and late Type II inclusions related to the fluid trapping during xenolith ascent. Homogenisation temperatures of fluid inclusions correspond to two density intervals: 0.93-0.68 g/cm3 (Type I) and 0.47-0.26 g/cm3 (Type II). Early Type I fluid inclusions indicate trapping pressures around 6 kbar, which are representative for the levels of partial melting of crustal rocks and xenolith formation. Late Type II fluid inclusions show lower trapping pressures, between 1.7 kbar and 0.2 kbar, indicative for shallow magma rest and accumulation during ascent to the surface. Data suggest the presence of two magma reservoirs: the first is located at lower crustal depths (about 24 km), site of fractional crystallization, mixing with source derived magma, and various degrees of crustal assimilation. The second magma reservoir is located at shallow crustal depths (about 6 km), the site where magma rested for a short time before erupting.

The first high-resolution bathymetric and backscatter maps of offshore Stromboli Island are presented, together with an interpretation of its volcanic, structural and sedimentary features. The volcanic edifice is characterized by a sub-conical shape with a quasi-bilateral symmetry with respect to a NE-SW axis. The dimensions of the Strombolicchio volcanic centre, to the NE of Stromboli, have been restored by redrawing its morphology before wave action that eroded it in Late Quaternary time. On the NE submarine flank of Strombolicchio, a N64°E structural trend controls the shape of Strombolicchio Canyon. On the southern side of Stromboli, the submarine flank has a radial structural trend, possibly reflecting a volcanic stress regime. Landslide scars at various scales are ubiquitous on the submarine slopes of Stromboli. Repeated large-scale lateral collapses have affected both the northwestern and southeastern unbuttressed flanks of the volcano, producing large debris avalanche deposits.

New detailed swath bathymetry and long-range side scan sonar data on the submerged flanks of Stromboli, integrated with seismic data and seabed sampling, indicate that repeated lateral instability processes occurred on the eastern flank of the volcano, although no debris avalanche deposits were known before the high-resolution exploration of the seabed. This flank of the island is opposite to the northwestern side, more evidently affected by repeated flank collapses, and this setting is evidence for a structurally-controlled, bilateral flank instability of the volcanic edifice. Evidence of at least two large-scale lateral collapses is represented by a superficial hummocky megablock field, partially outcropping on the middle-lower eastern submerged slope, and by a chaotic unit (estimated volume is 1-2 km3) actually embedded within the volcaniclastic sequence at the foot of the submerged flank. A main submarine scar open towards the SE is carved in the upper slope on the eastern flank of the island, being partially filled with gravity flow deposits owing to the present-day depositional setting of the volcano's submerged flank. A morphological continuity can be envisaged between this submerged scar and an inferred subaerial one, likely encompassing the Rina Grande depression and several minor nested landslide scars recognized on the eastern Stromboli flank. A spatial and temporal reconstruction of possible events is proposed. The chaotic debris avalanche unit, buried within the volcaniclastic apron at the slope base and partially reworked in its distal part within the Stromboli Canyon floor, is thought to be the result of a lateral collapse event (called Paleostromboli Lateral Collapse, PLC, as it likely occurred in the earlier stages of the subaerial development of the island) affecting a wide sector of the eastern Stromboli flank. The megablock field might instead result from a more superficial debris avalanche deposit, partially eroded by gravity flows currently acting on the seabed. It is tentatively related to the recent subaerial scar morphologies affecting the Vancori units (and for this reason named Vancori Lateral Collapse, VLC). Displaced materials have lower volume and mobility than the PLC. © 2009 Elsevier B.V. All rights reserved.

Brown Tuffs (BT) are volcaniclastic ash deposits prominently represented in the stratigraphic profiles of all the Aeolian Islands (and Capo Milazzo on the northern coast of Sicily). Detailed stratigraphy and tephrochronology together with available radiometric ages suggest that they were emplaced over a long time interval spanning from the end of the last interglacial period (ca. 80 ka BP) up to 4–5 ka BP (age of the overlying Punte Nere pyroclastic products on Vulcano). The most complete BT succession is documented on Lipari where 14 distinct and successive units are subdivided by the interbedding of widespread tephra layers, local volcanic products, paleosols and epiclastic deposits and the occurrence of local erosive surfaces. Inter-island occurrence of Ischia-Tephra (a widely known tephra layer in the Aeolian archipelago dated at 56 ka BP) and Monte Guardia pyroclastics from Lipari (dated at 22–20 ka BP) subdivides the BT succession in Upper (UBT), Intermediate (IBT) and Lower BT units (LBT), which can be correlated at regional level: the LBT was emplaced between 80 and 56 ka BP, the IBT between 56 and 22 ka BP and the UBT between 20 and 4–5 ka BP. On the basis of stratigraphy, similarity in lithology and textural features, morphology of glass fragments, composition and consistency of thickness and grain-size variations, UBT units correlate with Piano Grotte dei Rossi tuffs on Vulcano island. They were generated by pulsating hydromagmatic explosive activity giving rise to pyroclastic density currents spreading laterally from a source located inside the La Fossa caldera on Vulcano island. Composition is in agreement with this hypothesis since UBT compositional features match those of Vulcano magmas erupted in that period. The effect of co-ignimbrite ash clouds (or associated fallout processes from sustained eruptive columns) is seen to explain the presence of UBT in areas further away from the suggested source (e.g. Salina and Lipari islands and Capo Milazzo). The origin of UBT exposed on Panarea island is still a matter of debate, due to contrasting compositional data. Due to large uniformity of lithological, textural and componentry characters with respect to the UBT, the lower portions of the BT succession (LBT-IBT) are considered to be the result of recurrent, large scale hydromagmatic eruptions of similar type. Moreover, for the IBT units, the correlation with Monte Molineddo 3 pyroclastics of Vulcano island (on the basis of lithological, compositional and stratigraphic matching) again suggests source(s) related to the Vulcano plumbing system and located within the La Fossa Caldera.

Using reconstructed unconformity-bounded stratigraphy, the geological evolution of Panarea and surrounding islets can be described in terms of the interaction between the growing volcano and sea-level fluctuations. From the recognition of marine deposits corresponding to marine oxygen isotope stage (MIS) 5 and of widespread Brown Tuff-type pyroclastic deposits on Panarea, two first-order unconformities (U I and U II ) of regional stratigraphic significance can be correlated with the island of Lipari and adopted as a means of correlation on an inter-island scale in the Aeolian Volcanic District. Then, two second-order and three third-order unconfomities, consisting of erosional surfaces related to minor sea-level fluctuations or to subaerial reworking operating during the phases of volcanic inactivity, are introduced. The construction of the volcanic edifice occurred during seven successive eruptive epochs of local volcanic activity, between 150 and 10 ka, with intervening dormant periods characterized by the activation of reworking processes in subaerial and marine environments, and by the emplacement of widespread pyroclastic deposits of external provenance.

On 28 December 2002, the persistent Strombolian activity at Stromboli was interrupted by the sudden onset of lava emission onto the Sciara del Fuoco slope, a horseshoe-shaped depression on the NW flank of the volcano. The effusive episode went on until 22 July 2003 and produced a cumulative volume of lavas of 11 × 106 m3 ranking the event as the largest occurred in the past 30 years. The eruptive vents were mainly located in the NE sector of the Sciara del Fuoco depression, at an elevation of 550–600 m a.s.l. On 30 December, the eastern portion of the Sciara del Fuoco collapsed producing a tsunamigenic landslide. On 5 April 2003, a paroxysmal eruption occurred at the summit craters during which crystal-poor pumiceous products were emitted. The paroxysm did not interrupt the lava emission. The Strombolian activity at the summit craters gradually resumed starting from March 2003 and fully recovered by the end of July. Periodic sampling of the lava at the active vents was carried out during the entire effusive event. All the analysed samples are shoshonitic basalts (SiO2 48.5–50.4 wt.%; K2O 2.1–2.4 wt.%) in the range of composition observed in the products erupted during the past 20 years. They bear about 50 vol.% zoned crystals of plagioclase An90–60, diopside–augite and olivine Fo70–73 in a compositionally homogeneous shoshonitic groundmass. Bulk rock major and trace element contents measured with different methodologies at different laboratories show only minor variations. Sr and Nd isotope ratios are close to those of the crystal-rich scoriae erupted in the previous years. Despite of small compositional variations related to the emptying of the zoned topmost portion of the conduit, the data show that the switch from Strombolian explosive to effusive activity is not associated with changes of the textures and composition of the erupted products. Slight but somehow systematic variation of trace elements and isotope ratios between products erupted before and after the 5 April eruption are likely accounted by limited mixing between the fresh, volatile-rich, crystal-poor, magma erupted as pumice during the paroxysm, and the volatile-poor, crystal-rich magma feeding the lava flow. The uniform composition of the erupted lava indicates the presence of a large volume of well-mixed, crystal-rich, homogeneous magma residing in the shallow plumbing system of the volcano. Two possible trigger mechanism of the effusive event are here proposed: (i) a discrete input of fresh magma into the lower part of the shallow magmatic system occurred some months before the eruption and was followed by crystallisation, degassing and mixing with the crystal-rich shallow magma which re-homogenised the system. These processes eventually led to the rise of the magma at a higher level and failure of the conduit walls. (ii) The onset of the effusion may represent the consequence of a gradual rise of the magma level in the conduits occurred in the past two decades. The process of progressive refilling, initiated after the 1985 effusive eruption, ultimately culminated on 28 December 2002 with the failure of the conduit wall and the opening of vents 100–150 m below the summit craters.

Rapid shoreline changes at Stromboli Island have been documented from maps and aerial photographs dating from 1938 to 2003. Shorelines digitized from aerial photographs, taken at decadal intervals on average, show that while cliffed tracts were relatively stable, beaches on the N and NE side of the island experienced alternating accretion and erosional stages linked, respectively, with the contemporary eruptions and with sediment redistribution and/or the washing out and loss of sediment to deeper waters. Sciara del Fuoco, on the central-western side of the island, is where most of the volcanic products have accumulated during the practically continuous activity of the last two thousands years; from there, sands and gravel drift alongshore and are added to beaches on the N and NE side of the island. A simple model of clockwise longshore drift along the W, N, and NE coasts of the island is presented, taking into account the influences of manmade structures on shoreline changes.

On 3rd November 2002, at about 3 km off-shore of Panarea Island (Aeolian Islands, Southern Italy), a series of gas vents suddenly and violently opened from the seafloor at the depth of 10-15 m, with an unusually high gas flux and superimposing on the already existing submarine fumarolic field. Starting from the 12th November 2002 a discontinuous geochemical monitoring program was carried out. The emissions consisted in an emulsion whose liquid phase derived from condensation of an uprising vapor phase occurring close to the fluid outlets without significant contamination by seawater. The whole composition of the fluids was basically H2O- and CO2-dominated, with minor amounts of typical «hydrothermal» components (such as H2S, H2, CO and light hydrocarbons), atmospheric-related compounds, and characterized by the occurrence of a significant magmatic gas fraction (mostly represented by SO2, HCl and HF). According to the observed temporal variability of the fluid compositions, between November and December 2002 the hydrothermal feeding system was controlled by oxidizing conditions due to the input of magmatic gases. The magmatic degassing phenomena showed a transient nature, as testified by the almost complete disappearance of the magmatic markers in a couple of months and by the restoration, since January 2003, of the chemical features of the existing hydrothermal system. The most striking feature of the evolution of the «Panarea degassing event» was the relatively rapid restoration of the typical reducing conditions of a stationary hydrothermal system, in which the FeO/Fe1.5O redox pair of the rock mineral phases has turned to be the dominating redox controlling system.

Results of thermophysical investigations into the lavas of the island of Lipari (Southern Tyrrhenian Sea) are presented. Samples selected for laboratory measurements belong to four main magmatic cycles, which produced basaltic-andesitic, andesitic and rhyolitic lavas. The wet-bulk density and the thermal conductivity measured on 69 specimens range from 1900 to 2760 kg m-3 and from 1.02 to 2.88 W m-1 K-1, respectively. Porosity is never negligible and its influence on density is maximum in rhyolites of the third cycle. The thermal conductivity is also influenced by the amount of glass. Rhyolitic obsidians show values lower than other rhyolites, although the latter rocks have a larger average porosity. The radioactive heat production determined on 36 specimens varies with the rock type, depending on the amount of U, Th and K. In basic lavas of the first cycle its value is 0.95°± 0.30 mW m-3, while in rhyolites of the fourth cycle it attains 6.68°±0.61 mW m-3. A comparison between results of g-ray spectrometry and X-ray fluorescence points out that the assumption of equilibrium in the decay series of the isotopic elements seems fulfilled. The information obtained is useful not only for the interpretation of geophysical surveys but also for the understanding of the geochemical characteristics of lavas.

The problem of large location uncertainties for seismicity occurring in the Southern Tyrrhenian Sea have been partially exceeded during the implementation of the long-term scientific mission of the TYrrhenian Deep sea Experiment (TYDE), which allowed the installation of 14 wide-band Ocean Bottom Seismometers (OBS) and Hydrophones (OBH) in the period December 2000 – May 2001 on the sea-bottom floor around the Aeolian and Ustica Islands. Local events recorded at landstations have been observed also on the seismograms of the Ocean Bottom Seismic Network (OBSN). Moreover, some hundreds of low magnitude events, undetected from the land networks, have been recorded. We combined the readings of body wave arrival times from OBS-OBH with those from landstations to localise seismic events. We focused our study on three clusters of events representative of the seismic activity of the area: (i) “deep” events, (ii) Ustica (iii) NE-Sicily. The analysis of the integrated data set of the seismicity off-shore and on-shore, obtained from the combined land-OBS seismic network (Ustica sequence and Deep events), has improved locations in terms of RMS residuals, azimuthal gap, epicentral and hypocentral errors. Moreover, further classes of events have been analysed: the first one includes some local events that could be located only by integrating single trigger readings from the few available land-stations with the OBSN-data; the second one comprises local events that have been detected only by the OBS-OBH stations. In particular, the last cluster underlines the importance of an OBSN in the Tyrrhenian deep basin to reveal its unknown intense micro-seismicity, permitting to better understand both the tectonic and geodynamic picture of the area.