Somma-Vesuvius Volcano Research Articles

Raw materials and building technologies in the public buildings of Pompeii after the earthquake of 62/63 CE: A diachronic analysis of mortars

The paper deals with the technological aspects of the construction site of Pompeii through the characterization of the mortars, focusing on the identification of raw materials, their supply areas, selection criteria and mixing techniques to evaluate the continuity and changes in the different construction phases. Thanks to a multidisciplinary protocol that integrates archaeological, architectural, minero-petrographic and geochemical analyses, the study reveals that the binders were obtained from burning limestones from Mt. Lattari, while the aggregates are compatible with products from the Somma-Vesuvius volcano. The mortars from the period before 62/63 CE are characterised by a careful selection and preparation of the raw material, while the mortars from the period after 62/63 CE indicate a less precise procedures, probably due to the urgent need for reconstruction after the earthquake. Despite these changes, the essential quality and hydraulic properties of the mortars remained intact, demonstrating the resilience of ancient building practises.

Enricofrancoite, KNaCaSi4O10, a new Ca–K–Na silicate from Somma–Vesuvius volcano, southern Italy

Abstract Enricofrancoite (IMA2023–002), ideally KNaCaSi4O10, is a new litidionite-group member found as the product of high-temperature alteration of hosting silicates with the enrichment by Cu-bearing fluids at the rock–fumaroles interface related to the 1872 eruption of Somma–Vesuvius volcano, southern Italy. It occurs as euhedral and platy crystals or crusts together with litidionite, tridymite, wollastonite and Al- and Fe-bearing diopside, kamenevite, perovskite, rutile, Ti-rich magnetite and colourless Si-glass. Single crystals of enricofrancoite are transparent colourless or light blue with a vitreous lustre. Mohs hardness is 5.5. Dmeas is 2.63(3) g/cm3 and Dcalc is 2.63 g/cm3. The mineral is optically biaxial (−), α = 1.542(5), β = 1.567(5),γ = 1.575(5); 2V(meas) = 60(2)° and 2Vcalc = 58°. The mean chemical composition (wt.%, electron-microprobe data) is: SiO2 64.81, Al2O3 0.03, TiO2 0.08, FeO 0.07, MgO 1.71, CaO 10.64, CuO 2.22, Na2O 8.56, K2O 11.41, total 99.94. The empirical formula based on 10 O apfu is: K0.90Na1.03(Ca0.71Mg0.16Cu0.10)Σ0.97Si4.02O10. The Raman spectrum contains bands at 133, 248, 265, 290, 335, 400, 438, 510, 600, 690 and 1120 cm–1 and the wavenumbers of the IR absorption bands are: 424, 470, 492, 530, 600, 630, 690, 750, 788, 970, 1040 and 1160 cm–1. The eight strongest lines of the powder X-ray diffraction pattern are [d, Å (I, %) hkl]: 6.75 (42) 01 $\bar{1}$ , 3.65 (20) 11 $\bar{2}$ , 3.370 (100) 02 $\bar{2}$ , 3.210 (52) 102, 3.051 (18) 111, 3.033 (25) 2 $\bar{1}\bar{2}$ , 2.834 (22) 02 $\bar{3}$ and 2.411 (72) 03 $\bar{2}$ . Enricofrancoite is triclinic, space group P $\bar{1}$ , unit-cell parameters refined from the single-crystal data are a = 7.0155(4) Å, b = 8.0721(4) Å, c = 10.0275(4) Å, α = 104.420(4)°, β = 99.764(4)°, γ = 115.126(5)° and V = 472.74(5) Å3. The crystal structure has been refined from single-crystal X-ray diffraction data to R1 = 0.035 on the basis of 2078 independent reflections with Fo > 4σ(Fo). Enricofrancoite is an H2O-free analogue of calcinaksite with 5-coordinated Ca2+ at the M site.

The Avellino Event. Cultural and Demographic Effects of the Great Bronze Age Eruption of Mount Vesuvius. Overview of main project results, publications and valorisation activities

Between 2015 and 2019, a team of archaeologists, palaeobotanists and geologists from the Universities of Groningen, Amsterdam and Leiden looked into the distal effects of a powerful eruption of the Somma–Vesuvius volcano in Campania on the former wetlands of the Agro Pontino and Fondi coastal plains in Central Tyrrhenian Italy. These wetlands are located c. 60 km south of Rome and between 90 and 140 km north-west of Mount Vesuvius. The ‘Avellino’ eruption took place during an advanced stage of the Early Bronze Age and was radiocarbon dated around 1900 BCE. This article reports on the results of the research programme “The Avellino Event: Cultural and Demographic Effects of the Great Bronze Age Eruption of Mount Vesuvius”, funded by the Dutch Research Council. The team’s main hypothesis, that people living in the surroundings of Mount Vesuvius in the Early Bronze Age who had time to escape the proximal effects of the eruption – pyroclastic flows and heavy ash falls – fled to the relative safety of nearby coastal areas to build a temporary or permanent new existence, was disproved by field evidence early on. No major environmental and archaeological impacts were evident in the archaeological and environmental record of the study area around the date of the eruption. Nonetheless, the research resulted in a significant increase in geological and palaeobotanical data, which has proved extremely useful for the reconstruction of the longue durée of human–landscape interactions. The Avellino tephra was a most reliable chronological horizon in this reconstruction contributing to the overall objectives of the long-running Pontine Region Project of the University of Groningen. This contribution contains an overview of the main results of the Avellino Event Project, including an overview of scientific publications, valorisation output, and a brief discussion of some remarkable spin-off projects.

Hydrological and volcano-related gravity signals at Mt. Somma–Vesuvius from ∼20 yr of time-lapse gravity monitoring: implications for volcano quiescence

SUMMARY We report on about 20 yr of relative gravity measurements, acquired on Mt. Somma–Vesuvius volcano in order to investigate the hydrological and volcano-tectonic processes controlling the present-day activity of the volcano. The retrieved long-term field of time gravity change (2003–2022) shows a pattern essentially related to the subsidence, which have affected the central part of the volcano, as detected by the permanent GNSS network and InSAR data. After reducing the observations for the effect of vertical deformation, no significant residuals are found, indicating no significant mass accumulation or loss within the volcanic system. In the north-western sector of the study area, at the border of the volcano edifice, however, significant residual positive gravity changes are detected which are associated to ground-water rebound after years of intense exploitation of the aquifers. On the seasonal timescale, we find that stations within the caldera rim are affected by the seasonal hydrological effects, while the gravity stations at the base of the Vesuvius show a less clear correlation. Furthermore, within the caldera rim a multiyear gravity transient is detected with an increase phase lasting about 4 yr followed by a slower decrease phase. Analysis of rain data seem to exclude a hydrological origin, hence, we hypothesize a deeper source related to the geothermal activity, which can be present even if the volcano is in a quiescent state. We infer the depth and volume of the source by inverting the spatial pattern of the gravity field at the peak of the transient. A volume of fluids of 9.5 × 107 m3 with density of 1000 kg m−3 at 2.3 km depth is capable to fit reasonably well the observations. To explain the gravity transient, simple synthetic models are produced, that simulate the ascent of fluids from a deep reservoir up to the depth of 2.3 km and a successive diffusion within the carbonate aquifer hosting the geothermal system. The whole process appears to not significantly affect the seismicity rate and the deformation of the volcano. This study demonstrates the importance of a 4-D gravity monitoring of a volcano to understand its complex gravity signals that cover different spatial and temporal scales. Discriminating the different contributions that mix up in the observed gravity changes, in particular those due to hydrologic/anthropogenic activities form those due to the geothermal dynamics, is fundamental for a complete and reliable evaluation of the volcano state.

Continuous Gravity Observations at Mt. Somma-Vesuvius with a gPhoneX Gravimeter: In-Depth Instrumental Response Characterization and Tidal Model

We report on the results of about 9 months of gravimetric recordings acquired at Mt. Somma-Vesuvius (SV) volcano (Southern Italy) with the new generation relative gravimeter gPhoneX#116 (gPh#116), which is a gravimeter specifically designed for continuous gravity recording. We also present the outcomes of an intercomparison experiment of the gPhone#116 conducted at the J9 gravity observatory in Strasbourg (France). In this intercomparison, we were able to check the scale factor of the meter with a high degree of precision by means of an intercomparison with 2 superconducting gravimeters (SGs) and a FG5-type absolute ballistic gravimeter. Multiple calibration approaches allowed us to validate the manufacturer's original calibration constants to a level of 1% accuracy and 0.1% precision. Moreover, we carried out a comparative study of the noise level of the gPh#116 with respect to the SGs and other spring meters routinely used in both prospecting and time-lapse gravimetry. It turns out that gPh#116 exhibits lower levels at hourly time-scales than other compared spring gravimeters (Graviton, gPhone#054, Scintrex-CG5). It was also possible to carry out a detailed study of the instrumental drift, a crucial topic for reliable monitoring of the long-term gravity variations in active volcanic areas. In fact, a challenge in time-lapse gravimetry is the proper separation of the instrumental variations from real gravity changes eventually attributable to recharge or drainage processes of magma or fluids in the feeding systems of active volcanoes. A negative finding coming out from the intercomparison is that, even when applying the tilt correction, the gravimetric residuals obtained with the gPh#116 are an order of magnitude larger and quite inconsistent with those obtained with co-located superconducting gravimeters. We guess this problem could be overcome by installing the gravimeter on an auto-levelling platform. From the analysis of the gravity records, a reliable tidal gravity model was derived, which we believe will help to improve the accuracy of volcano monitoring, as it will allow appropriate correction of tidal effects for both relative and absolute gravity measurements acquired in the area. Two further interesting elements arose from our study: (1) a peculiar cavity effect of the SV underground laboratory that seems to influence the tilt change; (2) the small residual gravity signals are time correlated with the rainfall peaks and are compatible with gravity decreases induced by increases in soil moisture above the gravimeter.

Physical and chemical characterization of the Pomici di Avellino ashes (3.9 ka) from Somma-Vesuvius volcano for future health hazard assessment

Volcanic ashes can threaten the human respiratory system through inhalation. In this study we investigated the physical and chemical characteristics of volcanic ashes from the Pomici di Avellino (PdA) eruption, an Early Bronze Age (ca. 3.9 ka) Plinian event from Somma-Vesuvius volcano, southern Italy, whose wide dispersal affected most of the Italian peninsula. In particular, we analysed particle size, shape, composition, and surface reactivity of samples from both proximal and distal locations. Our results indicate that some tephra layers north of Rome have a phonolitic composition and match that of PdA eruption; they reach grain-sizes <2 μm (∼13.5%), thus having the potential to enter the deep respiratory system. Furthermore, the reactivity in free radical generation makes these products potentially able to cause oxidative stress within cells. While commonly no volcanic hazard assessment is made in areas far from active volcanoes, this study highlights that fine ashes from future similar large eruptions, producing high amount of highly fragmented material, can pose a health hazard even in remote, non-volcanic areas, hundreds of km away from the vent, suggesting that further studies on ash toxicity (e.g., in vitro toxicity studies) are required.

Genetic implications, composition, and structure of trioctahedral micas in xenoliths related to Plinian eruptions from the Somma-Vesuvius volcano (Italy)

Abstract The present work is part of a systematic mineralogical and petrographic characterization of mica-bearing xenoliths from Somma-Vesuvius volcano (Roman Magmatic Province, southern Italy). Skarns, composite skarns-marbles and cumulates from Pompeii Plinian eruption (AD 79), and skarns and syenite from Avellino eruption (3945 ± 10 cal yr BP) were investigated to define the crystal chemistry of the Somma-Vesuvius trioctahedral micas and to draw inferences on petrogenetic processes to which they were subjected. Xenoliths were characterized by means of polarized optical microscopy, scanning electron microscopy (SEM-EDS), X-ray powder diffraction (XRPD), and bulk-rock geochemical analyses. Mica crystals were studied using electron microprobe analysis (EMPA) and single-crystal X-ray diffraction (SCXRD). Micas from skarns are variably associated with Mg ± Ca silicates (clinopyroxene, vesuvianite, humite, clinohumite, chondrodite, forsterite, and garnet), other sporadic silicates (anorthite, sodalite, titanite, and britholite), apatite, calcite, various types of oxides, as well as rare sulfides and halides. In composite skarn-marble rocks, the mineral assemblages show some differences compared to skarns, as a lack of clinopyroxene and the presence of dolomite. Cumulate samples consist of mica and clinopyroxene, whereas syenite is mainly composed of mica, K-feldspar, feldspathoids, and clinopyroxene. Together with mica, apatite occurs in all the lithotypes. Trace element arrays are scattered for skarn and composite skarn-marble samples. The REE patterns have a general enrichment in light (La, Ce, Pr, Nd) and medium (Sm, Eu, Gd, Tb, Dy) rare earth elements, in some cases with slight positive Gd anomaly. Cumulate samples generally have low amounts of Ba, Sr, Zr, and Th, while syenite exhibits low concentrations of trace elements, except for Rb, Cs, and Tl. Mica crystals occurring in the studied xenoliths are phlogopite with different Al and Mg contents at the octahedral site, a negligible tetraferriphlogopite component and variable dehydrogenation degree. All samples belong to the 1M polytype (C2/m and C2 space group) and have a wide range of unit-cell parameters, especially of the c axis [5.3055(1) ≤ a ≤ 5.3218(1) Å, 9.1893(1) ≤ b ≤ 9.2188(4) Å, 10.1803(2) ≤ c ≤ 10.2951(2) Å]. The shortest c-cell parameter pertains to de-hydrogenated phlogopite from Avellino skarn, whereas OH-rich phlogopite from Pompeii composite skarns-marbles has a c-cell parameter that approximates that of the end-member phlogopite. Overall, it is observed that the crystal chemistry of the micas studied here extends the known range of the other Vesuvian micas from the literature. The Ti-depletion and the wide degree of dehydrogenation of phlogopites from skarns and composite skarns-marbles suggest that the studied samples originated under variable pressure conditions. In addition, the presence of humite in the mineral assemblage seems to indicate the occurrence of devolatilization reactions. The scarce mica occurrence in cumulate and mainly in syenite, instead, may depend on pressure conditions in the magma storage system exceeding the mica stability.

The complex mechanism of Ti4+ incorporation into litidionite from the Somma–Vesuvius volcano, Italy

AbstractFor this study, the rare Cu-bearing silicate fumarolic assemblages from the Somma–Vesuvius volcano, Italy, characterised by the rare mineral litidionite, CuKNaSi4O10, were investigated. We report new data about Cu- and Ti-bearing phases found in these mineralisations, in which Ti-bearing litidionite occurs together with kamenevite, perovskite and rutile. Ti-bearing litidionite appears on the latest stages of partial crystallisation of Ti-bearing silica glass. Incorporation of Ti4+ into the litidionite crystal structure was investigated in detail. The Raman spectra of Ti-bearing litidionite contains an intense band at 597 cm−1 related to anti-symmetric bending vibrations of Si‒O bonds or overlapping stretching vibrations of Ti‒O bonds. The bands in the range 350‒500 cm−1 correspond to symmetric bending vibrations of O‒Si‒O bonds and overlapping stretching vibrations of Ti‒O bonds. The crystal structure of Ti-litidionite has been refined in the P$\bar{1}$ space group, a = 6.9699(7), b = 7.9953(10), c = 9.8227(10) Å, α = 105.186(9), β = 99.458(8) and γ = 114.489(10) to R1 = 0.064 for 1726 unique observed reflections. The refinement of the site-occupation factors confirmed the presence of Ti at a five-coordinated M site. The mean bond distance of 2.125 Å for the M site agrees with its refined occupancy (Ti0.32Cu0.30Ca0.29Fe0.09)1.00. The incorporation of Ti into the litidionite structure is accompanied by the complex heteropolyhedral substitution according to the scheme VTi4+ + VII–VIII□ + IVAl3+ ↔ VCu2+ + VII-VIII(Na,K)+ + IVSi4+. Two possible configurations for the phase with maximal TiO2 content (12.06 wt.% or 0.56 Ti apfu) CuTiK□Na2Si7AlO20 (Z = 1) or CuTiK2Na□Si7AlO20 (Z = 1) have been proposed.

The Ground Deformation History of the Neapolitan Volcanic Area (Campi Flegrei Caldera, Somma–Vesuvius Volcano, and Ischia Island) from 20 Years of Continuous GPS Observations (2000–2019)

The Neapolitan volcanic area includes three active and high-risk volcanoes: Campi Flegrei caldera, Somma–Vesuvius, and Ischia island. The Campi Flegrei volcanic area is a typical example of a resurgent caldera, characterized by intense uplift periods followed by subsidence phases (bradyseism). After about 21 years of subsidence following the 1982–1984 unrest, a new inflation period started in 2005 and, with increasing rates over time, is ongoing. The overall uplift from 2005 to December 2019 is about 65 cm. This paper provides the history of the recent Campi Flegrei caldera unrest and an overview of the ground deformation patterns of the Somma–Vesuvius and Ischia volcanoes from continuous GPS observations. In the 2000–2019 time span, the GPS time series allowed the continuous and accurate tracking of ground and seafloor deformation of the whole volcanic area. With the aim of improving the research on volcano dynamics and hazard assessment, the full dataset of the GPS time series from the Neapolitan volcanic area from January 2000 to December 2019 is presented and made available to the scientific community.

Capillary Barriers during Rainfall Events in Pyroclastic Deposits of the Vesuvian Area

In the present paper, the capillary barrier formation at the interface between soil layers, which is characterized by textural discontinuities, has been analyzed. This mechanism has been investigated by means of a finite element model of a two-layer soil stratification. The two considered formations, belonging to the pyroclastic succession of the “Pomici di Base” Plinian eruption (22 ka, Santacroce et al., 2008) of the Somma–Vesuvius volcano, are affected by shallow instability phenomena likely caused by progressive saturation during the rainfall events. This mechanism could be compatible with the formation of capillary barriers at the interface between layers of different grain size distributions during infiltration. One-dimensional infiltration into the stratified soil was parametrically simulated considering rainfall events of increasing intensity and duration. The variations in the suction and degree of saturation over time allowed for the evaluation of stability variations in the layers, which were assumed as part of stratified unsaturated infinite slopes.

Topography and structural heterogeneities in surface ground deformation: a simulation test for Somma-Vesuvius volcano

Abstract. We simulate the deformation of Somma-Vesuvius volcano due to some overpressure sources by means of a finite element 3D code. The main goal of these simulations is to investigate the influence of topography and structural heterogeneity on ground deformation. In our model the sources of deformation are embedded in an elastic linear isotropic medium and located at various depths. Geometry (shape and lateral extension) of the sources is mainly constrained by the results coming from recent seismic tomography studies. The structural heterogeneity has been modelled in terms of dynamic elastic parameters (Young's modulus) retrieved from previous seismic tomography and gravity studies. A high-resolution digital terrain model is used for the topography of the volcano subaerial edifice. Evidences from our results suggest that real topography and structural heterogeneities are key factors governing the ground deformation, which often turns being one of the most relevant problems in volcano monitoring. A large deviation from the axially symmetrical model of the displacement field is the main result of our modelling. Such an asymmetry is routinely unaccounted for when Mogi's simplistic modelling in a homogeneous medium with simplified topography is used. Our study clearly demonstrate that a better knowledge of deformation patterns can significantly help in the location of monitoring sensors as well as in the design of an efficient geodetic network.

The use of historical cartography and ALS technology to map the geomorphological changes of volcanic areas: A case study from Gran Cono of Somma-Vesuvius volcano

The eruptive activity of a volcano modifies its surface topography through morphological changes generated by the deposition of emitted volcanic material and resulting gravity-driven processes, which can form accumulation of material in addition to the most common erosional phenomena. Mapping and quantifying such morphological changes allow to derive new data useful to better describe and understand the eruptive history of the volcano itself. Nowadays, one of the mostly used method to identify such morphological changes consists of comparing Digital Elevation Models (DEM) of the volcanic area before and after an eruptive event. If the eruptive event is referred to periods prior to 1980's, the only method to reproduce DEMs consists of elaborating the historical cartography that is often available only in paper format. In this work we aim to prove the reliability of this approach, presenting a study on the morphological changes (from 1876 to 1944) of the summit caldera of the Somma–Vesuvio volcano (Italy). For the first time, we compare DEMs derived from historical maps (1876, 1906 and 1929) and a DEM dated 2012 obtained by remote sensing. The four models of the caldera, digitally reproduced at the same spatial resolution, are morphologically investigated through specific maps derived from the DEMs and a set of height profiles. In addition, further morphometric analyses and accurate quantifications in volume and surface are presented and discussed for a portion of the Somma-Vesuvio summit caldera, represented by the Gran Cono edifice. Considering the different typology of the source data used in this study, it is also provided a discussion on the respective accuracies that, especially for the historical maps, represent a crucial point for obtaining DEMs able to reproduce topographies more realistic as possible. For this reason, despite data source were processed following rigours criteria, the calculations of volume, surface and distance related to the morphological changes of the volcano are associated to an accurate quantification of the error. Following this, the main results obtained in this study are: i) the identification of several past volcanic deposits and the estimation of the related thicknesses, both in good agreement with published literature; ii) the quantification of the morphological changes of the Gran Cono from 1876 to 1944 resulting in a volume and surface growth of 133 × 106 m3 (±5%) and ~0.14 km2, respectively; iii) the identification of a possible migration path of the centroid of the Gran Cono crater along the SW-NE preferential direction during the investigated period.

Reproducing pyroclastic density current deposits of the 79 CE eruption of the Somma–Vesuvius volcano using the box-model approach

Abstract. We use PyBox, a new numerical implementation of the box-model approach, to reproduce pyroclastic density current (PDC) deposits from the Somma–Vesuvius volcano (Italy). Our simplified model assumes inertial flow front dynamics and mass deposition equations and axisymmetric conditions inside circular sectors. Tephra volume and density and total grain size distribution of EU3pf and EU4b/c, two well-studied PDC units from different phases of the 79 CE Pompeii eruption, are used as input parameters. Such units correspond to the deposits from variably dilute, turbulent PDCs. We perform a quantitative comparison and uncertainty quantification of numerical model outputs with respect to the observed data of unit thickness, inundation areas and grain size distribution as a function of the radial distance to the source. The simulations consider (i) polydisperse conditions, given by the total grain size distribution of the deposit, or monodisperse conditions, given by the mean Sauter diameter of the deposit; (ii) axisymmetric collapses either covering the whole 360∘ (round angle) or divided into two circular sectors. We obtain a range of plausible initial volume concentrations of solid particles from 2.5 % to 6 %, depending on the unit and the circular sector. Optimal modelling results of flow extent and deposit thickness are reached on the EU4b/c unit in a polydisperse and sectorialized situation, indicating that using total grain size distribution and particle densities as close as possible to the real conditions significantly improves the performance of the PyBox code. The study findings suggest that the simplified box-model approach has promise for applications in constraining the plausible range of the input parameters of more computationally expensive models. This could be done due to the relatively fast computational time of the PyBox code, which allows the exploration of the physical space of the input parameters.

Risk and Vulnerability on the Campanian Plain: The Vesuvius Eruption of A.D. 472

The projects of social history, disaster studies, and archaeology deliberately tend to eschew consideration of events, focusing instead on processes and structures that unfold gradually over time. The eruption of the Somma-Vesuvius volcano in Campania, Italy, in 472 presents tangible markers of a specific moment, although the absence of local textual evidence and the strong hints of rapid re-exploitation of the rich and fertile soils of the region suggest that the scale of the disaster that it precipitated was limited. A perspective on the eruption informed by the concepts of risk and vulnerability demonstrates that the population of the Campanian Plain had different experiences of the eruption according to factors such as their location, the nature and robustness of their social and economic resources, and their mechanisms for accessing and exploiting power relationships.

Volcanic evolution of the Somma-Vesuvius Complex (Italy)

ABSTRACT A volcanological map of the active Somma-Vesuvius volcano is presented at the 1:20,000 scale. The map is based on 1:5000 field mapping carried out during the Italian CARG project. Geological data are represented on a digital terrain model of the volcano. This allows a better visualisation of the main morphological, volcanic, and geological features. The legend is organised in four different panels, which depict the activity of the volcano and caldera development. The geological survey is based on recognition and description of lithostratigraphic units. The geological map highlights the volcanic evolution of the Somma-Vesuvius volcano, and it is propaedeutic for further studies aimed at improving the scientific knowledge and the volcanic hazard assessment of this world-famous volcano.

Copper Minerals at Vesuvius Volcano (Southern Italy): A Mineralogical Review

This work is part of a project focused on the Somma–Vesuvius volcano and aimed at identifying Cu minerals related to mineralizing processes associated with magmatic activity in an active magmatic-hydrothermal system. A mineralogical survey was carried out on a set of samples represented by sublimates and fumarolic products from the collection of the Mineralogical Museum of the University of Naples Federico II (Italy). These samples are mainly related to most recent eruptive episodes of Vesuvius activity, from 1631 onward. Copper-bearing minerals were characterized, as well as associated minerals, by X-ray diffraction (XRD) scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). An investigation on the structural complexity of Cu-mineral assemblages with different temperature formations was also carried out using the TOPOS software package. The main copper phases are sulfates, followed by vanadates, hydroxyhalides, oxides, carbonates, silicates and finally, phosphates. New mineral occurrences for Vesuvius, both Cu-bearing and Cu-free, are described. Nevertheless, the fumarolic/alteration minerals at Vesuvius cannot be considered of economic relevance as a copper reservoir, this type of mineralizations are significant for copper crystal chemistry and for the knowledge of the mineralogical variants. The obtained datasets can be of interest for the knowledge of volcanic byproducts of copper ore deposits (i.e., porphyry copper systems) and of (base) metal segregation processes.

Characterizing magma fragmentation and its relationship with eruptive styles of Somma-Vesuvius volcano (Naples, Italy)

Among the active volcanoes worldwide, Somma-Vesuvius is one with the highest volcanic risk as the surrounding areas are highly populated. Somma-Vesuvius is quiescent since 1944, but geological and historical records reveal a frequent violent explosive activity in the last 4000 years, representing a severe risk for the ∼700,000 inhabitants currently living in the area having a high probability for being impacted by pyroclastic density currents (“red zone”) and more than one million people who can be potentially affected by tephra fallout. This study aims to analyze the distribution and grain-size of tephra fallout deposits from several Somma-Vesuvius eruptions of different styles, ranging from Violent Strombolian to sub-Plinian and Plinian, for characterizing the associated magmatic fragmentation through the assessment of their total grain-size distribution (TGSD). Chronologically, we focus on the Avellino (4365 BP) and Pompeii (A.D. 79) Plinian eruptions, the Pollena (A.D. 472) sub-Plinian eruption, and the 1906 and 1944 Violent Strombolian eruptions. The related TGSDs were estimated by means of the Voronoi tessellation method, which requires a suitable number of local grain-size distributions and estimation of the area of minimum tephra loading (zero-line contour). However, field-derived TGSDs can be biased towards the coarse and fine grain-size populations due to the typical paucity of available field outcrops of fallout deposits. To encompass this issue, we performed a sensitivity study on the assumption behind TGSD reconstructions and described TGSDs through analytical grain-size distributions that best fit the field TGSDs. Our main objective is a more robust estimation of the TGSDs associated with the different eruptive styles, which is crucial, together with the other eruption source parameters, for robustly predicting tephra loading and airborne ash dispersal of future eruptions at Somma-Vesuvius.

The city of the sun and Parthenope: classical astronomy and the planning of Neapolis, Magna Graecia

This paper investigates what may have been the cosmological and religious inspirations for the plan of the city of Parthenope-Neapolis (the historic centre of Naples, Italy), which was founded in the early fifth century BC by Greek colonists. Neapolis anticipated the strict orthogonal Hippodamian street grid plan. We argue that its geometry and geographical orientation was chosen so that Neapolis could be recognized as the city of Helios/Apollo (the sun-god of the Greeks) and Parthenope, the deified royal ancestor and/or the siren after whom the city was named. In fact, Neapolis's streets were cosmologically oriented using a sixteen-rayed hexadecagram geometry to emphasize Apollonian/solar cults. The city was also planned using a Pythagorean decagram/pentagram design with golden section proportions and inscribed geometries to symbolize the Harmony of the Spheres. These geometries were apparently inspired by the specific paths of the sun seen from the city on the solstices. Moreover, a sort of celestial light show on the spring and autumn equinoxes connected the sun, the Somma-Vesuvius volcano complex, Sant’ Elmo hill, the constellations of Taurus, Virgo/Parthenos and Aquila with the cult of Sebethos and Parthenope, the parent gods of Neapolis. Finally, Vitruvius's ideal city design appears to indicate that the novel and advanced planning of Neapolis served as a prototype for subsequent Greek and Roman cities.

Quantitative interpretation of multiple self-potential anomaly sources by a global optimization approach

Multiple self-potential (SP) anomalies are analyzed by using a Genetic-Price Algorithm (GPA), which has been recently introduced for the inversion of SP data. The proposed approach is tested on multiple synthetic anomalies, which are modeled by horizontal cylinders. First, a forward modeling is used to analyze the resolution of such anomalies by varying all model parameters. Then, GPA is applied to invert synthetic multiple SP anomalies. The numerical analyses show that the proposed approach is able to fully characterize the anomaly sources by providing the correct values of the model parameters as well as the number of sources, even if Gaussian random noise is added to the synthetic data. Furthermore, to show the computational efficiency of GPA, the results of a comparative analysis with the Very Fast Simulated Annealing algorithm are given. The validity of the GPA approach is confirmed by its application to three examples of self-potential field data from mineral exploration and groundwater investigations, which are presented and discussed in relation to other inversion approaches. Finally, the quantitative interpretation of multiple anomalies along a SP profile crossing the Mt. Somma-Vesuvius volcano caldera (southern Italy) is provided.

Trachy-phonolite lava pebbles used in the ancient settlement of Oplontis (Torre Annunziata, Naples): petrochimical data supporting the origin from an old effusive activity of the Somma-Vesuvius volcano

In the southern and south-eastern sectors of Somma-Vesuvius volcano (Campania region, southern Italy), archaeological sites covered by the deposits of A.D. 79 Vesuvius eruption, and dating back to Protohistoric and Roman periods are characterized by the presence of numerous lava pebbles used in the human settlements. In this work we present the new case study of the lava samples found with other materials used in building foundations of the Roman site of Oplontis (the “ Villa of Poppea” or “Villa A” or Oplontis A ; and the ancient commercial structure of Oplontis B ). This new data set of lava pebbles of different lithologies was also compared with that of the archaeological site of Longola, in order to unravel the source provenance from distinct evolutionary phase of the Somma-Vesuvius volcano. According to major and trace elements composition, lava pebbles are all compatible with the Somma-Vesuvius magmas erupted before 8 ka BP and are represented, according to modal mineralogy and whole-rock geochemistry, by two groups belonging to the slightly silica undersaturated series: several basic-intermediate lithotypes (mainly phonolitic tephrites to basaltic trachyandesites) and trachy-phonolites . Despite the obvious abundance of volcanic rock pebbles, as the settlements were built on the Somma-Vesuvius volcano, the trachy-phonolite lava pebbles do not match with any lithostratigraphic units mapped in the up-to-now available literature data. Nevertheless, the trachy-phonolite lava pebbles show (i) a comagmatic relationships with the products erupted by Somma-Vesuvius before 8 ka BP as pyroclastic products (i.e. pumices) and (ii) a good petrological affinity with lava trachyte ejecta included within the Plinian eruptions preceding the A.D. 79 event. The basic-intermediate and the trachy-phonolite lava pebbles from both the sites of Oplontis and Longola, have to be interpreted as an old effusive activity of the Somma-Vesuvius. In order to form lava pebbles, reworking could have taken place both on the original lava flows/autoclastic breccias or the lithic lava fragments of pyroclastic/breccia deposits produced by the explosive events preceding the A.D. 79 eruption.