Activity Of Vesuvius Research Articles

Helium isotopes in Plinian and inter-Plinian volcanic products of Vesuvius, Italy

We investigated helium isotopes on gas extracted by crushing from melt and fluid inclusions in minerals from Plinian and inter-Plinian tephra and lavas of Vesuvius, Italy. Erupted products of different ages were considered, from Avellino eruption (1995 BCE) to the last eruption of 1944, with special focus on the 79 AD Plinian eruption. He/He 4 3 ratios between 1.5 and 2.7 RA were measured, with the highest values associated with rocks representative of the roof and the walls of the magma chambers (cumulates). Lowest values occurred in sanidines representative of magma-skarn interfaces. Noteworthy, the highest measured values of the 79 AD pumices were comparable with both lavas and tephra emitted from flank vents and under open-conduit conditions during the Medieval Period and Present Period of Vesuvius activity, and present-day fumarolic discharges. He 3/He 4 values are buffered within an extended, deep-seated reservoir at about 10 km filled with magma rising from the mantle. A fact that might potentially limit the accuracy of future eruption forecasting through monitoring of He/He 4 3 changes in Vesuvius fumaroles. Ageing and interaction with crustal rocks emerged as possible mechanisms that lowered the He/He 4 3 ratio of the melt during its intra-crustal magma chambers stay, with highest values associated with more dynamic conditions.

THE ‘MASSERIA ROTA’ IN NAPLES (ITALY). A VERNACULAR HERITAGE TO PRESERVE

Abstract. The ‘Masseria Rota’ in Cercola, near Naples, is one of the best-preserved examples of the important vernacular architectural heritage of the Vesuvian area. Built in the 17th century upon more ancient pre-existences, the farm is an extraordinary example of the construction capabilities typical of the Neapolitan area and the dual vocation, productive and residential of the Vesuvian ‘masserie’. The production area for slaughter and winemaking – located on the basement floor and still in good condition – coexists with the residential part with a sober decorative apparatus, enriched by the nineteenth-century transformations. Its planimetric U-shaped layout denounces a development for subsequent integrations that is also evident from the mensiochronological analysis of the walls. Unfortunately, despite the its indisputable historical, architectural and documentary value, the ‘Masseria Rota’ is in a serious state of abandonment, suffocated by contemporary buildings often devoid of specific values. The contribution to be presented illustrates the results of a teaching experiment that aims to propose methodological guidelines for the drafting of a restoration project aware and respectful of the identity of the aforementioned 'Masseria', and intends to provide a contribution of knowledge for the preservation and enhancement of a vernacular building heritage present on the slopes of Vesuvius, guiltily forgotten and abandoned in recent decades, which, instead, represents one of the most interesting and important of the settlement and construction modes of a territory inhabited since antiquity – despite the cyclical destructions caused by the volcanic activity of Vesuvius – for its environmental and landscape characteristics.

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.

Cultural climate in Naples between the birth and development of volcanology

With the Industrial Revolution the laws of physics were introduced to explain natural phenomena. At that time the Vesuvian Observatory emerged as the first volcanological observatory in the world to monitor the activity of Vesuvius on a permanent basis. Naples became an attractor for scholars, who were to analyze volcanic phenomena by developing relationships between the science of laws and those of processes. After World War I interest in Naples-based volcanology further increases, as attested by the founding in the city of Immanuel Friedlaender's International Institute of Volcanology. Following the twenty-year Fascist period, Italy had two objectives: to reconstruct the network of science laboratories and rebuild the approach to studying Earth Sciences through comparison with more advanced countries. Significant and original contributions were made regarding the new theory of global tectonics and the mitigation of natural risks.

Subcircular conduits and dikes offshore the Somma‐Vesuvius volcano revealed by magnetic and seismic data

AbstractWe analyzed new magnetic, bathymetric, and seismic data acquired in the offshore sector of Somma‐Vesuvius volcano (Italy). We detected a group of high‐intensity, short wavelength magnetic anomalies corresponding to partly buried volcanic dome‐like structures located by seismic data. The magnetic anomalies are aligned along a NW‐SE strike that is the preferential orientation of an eruptive fracture of the pre‐19 ka activity of Vesuvius. Four cones emplaced after the Last Glacial Maximum (19 ka), whereas a fifth one emplaced more recently suggesting a rejuvenation of the eruptive system offshore the volcano in historical times. We also identified a NE‐SW elongated magnetic anomaly consistent with a dike‐like body associated to an on‐land tectonic structure that was active in recent times at Vesuvius. A delta‐like area with diffuse low‐intensity magnetic anomalies reflects the seaward fronts of lava flows that entered the sea mainly during the Middle Ages.

The 2nd to 4th century explosive activity of Vesuvius: new data on the timing of the upward migration of the post-A.D. 79 magma chamber

<p>We present volcanological data on the deposits of the Santa Maria Member (SMM), the eruption cycle occurred at Vesuvius (Italy) in the period between the A.D. 79 plinian and the A.D. 472 subplinan eruptions. Historical accounts report only sporadic, poorly reliable descriptions of the volcanic activity in this period, during which a stratified sequence of ash and lapilli beds, up to 150 cm thick, with a total volume estimated around 0.15 km<span><sup>3</sup></span>, was widely dispersed on the outer slopes of the volcano. Stratigraphic studies and component analyses suggest that activity was characterized by mixed hydromagmatic and magmatic processes. The eruption style has been interpreted as repeated alternations of continuous and prolonged ash emission activity intercalated with short-lived, violent strombolian phases. Analyses of the bulk rock composition reveal that during the entire eruption cycle, magma maintained an homogeneous phonotephritic composition. In addition, the general trends of major and trace elements depicted by the products of the A.D. 79 and A.D. 472 eruptions converge to the SMM composition, suggesting a common mafic end-member for these eruptions. The volatile content measured in pyroxene-hosted melt inclusions indicates two main values of crystallization pressures, around 220 and 70 MPa, roughly corresponding to the previously estimated depth of the magma reservoirs of the A.D. 79 and A.D. 472 eruptions, respectively. The study of SMM eruption cycle may thus contribute to understand the processes governing the volcano reawakening immediately after a plinian event, and the timing and modalities which govern the migration of the magma reservoir.</p>

The ShakeMap Atlas for the City of Naples, Italy

Online Material: Tables of felt earthquakes in Naples and analysis for historical completeness; overview of geological settings of Naples; ground ShakeMap for the 84 earthquakes in Naples with I s >4 Naples is one of the most vulnerable cities in the world because it is threatened by several natural and man‐made hazards: earthquakes, volcanic eruptions, tsunamis, landslides, hydrogeological disasters, and morphologic alterations due to human interference. In addition, the risk is increased by the high density of population (Naples and the surrounding area are among the most populated in Italy), and by the type and condition of buildings and monuments. In light of this, it is crucial to assess the ground shaking suffered by the city. To create a ShakeMap atlas for the region and to reconstruct the seismic history of the city from historical to recent times, we gather information from the most reliable and complete databases of macroseismic intensity records dating back to the eleventh century. The events felt in Naples cover a time span ranging from 1293 to 1999. The first event ( M w 5.8) was an earthquake in 1293, located in the southern Apennines, at a distance of 100 km from Naples. The most recent event was an earthquake of moderate magnitude in 1999, located beneath Vesuvius (Fig. 1). In the previous release of the macroseismic databases, two additional events associated with the volcanic activity of Vesuvius in 62 and 79 A.D. were included. They are not included in the new release of the databases because they occurred before 1000 A.D., and likewise they have been not included in this atlas because they are too ancient to be incorporated into any time and magnitude window of completeness. For instrumental events (e.g., after 1980), we merge these macroseismic records with strong‐motion data. Basically, we integrate information from …

Analysis of the activity pattern of volcanoes through self-organized crack networks: The effect of density barriers—An application to Vesuvius activity in the period 1631–1944

We simulated the pattern of activity of a strato-volcano by using a cellular automaton model where magma is allowed to ascend to the surface through self-organized crack networks. Magma rises toward the surface by filling connected paths of fractures until the magma's density is less than that of surrounding rocks. If magma enters a region with negative or neutral buoyancy, it cools and solidifies; as a result, the local density profile is modified, and magmatic dikes are formed. We simulated the temporal evolution of high-density pathways of dikes that magma may eventually utilize to reach the surface. We showed that if a shallow neutral–negative buoyancy zone is restored after eruptions, due to, for example, piecemeal or chaotic collapses, a characteristic timescale appears in the inter-event repose time distribution. Such characteristic repose time represents the average time that magma takes to form a high-density pathway through the less dense rock layer, and it may give a hint to predict possible eruptive scenarios. Even if the model includes many simplifying assumptions in the definition of magma–rock interaction, the results obtained from simulations are consistent with the eruptive behavior of the Mt. Somma-Vesuvius volcano for the 1631–1944 period.

Ash fallout scenarios at Vesuvius: Numerical simulations and implications for hazard assessment

Volcanic ash fallout subsequent to a possible renewal of the Vesuvius activity represents a serious threat to the highly urbanized area around the volcano. In order to assess the relative hazard we consider three different possible scenarios such as those following Plinian, Sub-Plinian, and violent Strombolian eruptions. Reference eruptions for each scenario are similar to the 79 AD (Pompeii), the 1631 AD (or 472 AD) and the 1944 AD Vesuvius events, respectively. Fallout deposits for the first two scenarios are modeled using HAZMAP, a model based on a semi-analytical solution of the 2D advection–diffusion–sedimentation equation. In contrast, fallout following a violent Strombolian event is modeled by means of FALL3D, a numerical model based on the solution of the full 3D advection–diffusion–sedimentation equation which is valid also within the atmospheric boundary layer. Inputs for models are total erupted mass, eruption column height, bulk grain-size, bulk component distribution, and a statistical set of wind profiles obtained by the NCEP/NCAR re-analysis. We computed ground load probability maps for different ash loadings. In the case of a Sub-Plinian scenario, the most representative tephra loading maps in 16 cardinal directions were also calculated. The probability maps obtained for the different scenarios are aimed to give support to the risk mitigation strategies.

Fingerprinting ash deposits of small scale eruptions by their physical and textural features

Correlation of distal ash deposits with their proximal counterparts mainly relies on chemical and mineralogical characterization of bulk rock and matrix glasses. However, the study of juvenile fragments often reveals the heterogeneity in terms of clast shape, external surface, groundmass texture and composition. This is particularly evident in small scale eruptions, characterized by a strong variability in texture and relative abundance of juvenile fragments. This heterogeneity introduces an inherent uncertainty, that makes the compositional data alone inadequate to unequivocally characterize the tephra bed. Pyroclast characteristics, if described and quantified, can represent an additional clue for the correct identification of the tephra. The paper presents morphological, textural and compositional data on the products of an ash eruption from Middle Age activity of Vesuvius, to demonstrate the information that can be extracted from the proposed type of analysis. Juvenile fragments from five ash layers throughout the studied products were randomly hand-picked and fully characterized in terms of external morphology, particle outline parameterization, groundmass texture and glass composition. Statistical analysis of shape parameters characterized groups of fragments that can be compared with the other textural and physical parameters. The main result is that the data do not show important cross-correlation so suggesting that all of these parameters, together with accurate field data are needed for the complete fingerprinting of a tephra bed. We suggest that this approach is especially important for characterizing the products of small scale, compositionally undistinguishable, eruptions and represents the necessary step to deal with before going into more detailed compositional analyses.

Burial of Emperor Augustus' villa at Somma Vesuviana (Italy) by post-79 AD Vesuvius eruptions and reworked (lahars and stream flow) deposits

A new archaeological site of Roman Age has been recently found engulfed in the products of Vesuvius activity at Somma Vesuviana, on the northern flank of the Somma–Vesuvius, 5 km from the vent. A 9 m deep, 30 by 35 m trench has revealed a monumental edifice tentatively attributed to the Emperor Augustus. Different than Pompeii and Herculaneum sites which were completely buried in the catastrophic eruption of 79 AD, this huge roman villa survived the effects of the 79 AD plinian eruption as suggested by stratigraphic and geochronologic data. It was later completely engulfed in the products of numerous explosive volcanic eruptions ranging from 472 AD to 1631 AD, which were separated by reworked material and paleosols. The exposed burial sequence is comprised of seven stratigraphic units. Four units are composed exclusively of pyroclastic products each emplaced during a unique explosive event. Two units are composed of volcaniclastic material (stream flow and lahars) emplaced during quiescent periods of the volcano. Finally, one unit is composed of both pyroclastic and volcaniclastic deposits. One of the more relevant volcanological results of this study is the detailed reconstruction of the destructive events that buried the Emperor Augustus' villa. Stratigraphic evidence shows the absence of any deposit associated with the 79 AD eruption at this site and that the building was extensively damaged (sacked) before it was engulfed by the products of subsequent volcanic eruptions and lahars. The products of the 472 AD eruption lie directly on the roman structures. They consist of scoria fall layers intercalated with massive and stratified pyroclastic density current deposits that caused limited damage to the structure. The impact on the building of penecontemporaneous lahars was more important; these caused the collapse of some structures. The remaining part of the building was subsequently entombed by the products of explosive eruptions (e.g. 512/536 eruption, 1631 eruption) and mass flows.

Vesuvius before the 1631 eruption

of which a printed transcription will shortly be published [Guidoboni, 2006], provided new data concerning the activity of Vesuvius 60 years prior to its last great eruption, on 16 December 1631. This activity, which had until now been unknown to modern science, calls for a re‐evaluation of the current conditions of the volcano and of possible precursors to the next major eruption.Vesuvius is one of the most dangerous volcanoes in the world: Its activity can affect an area comprising 18 municipalities that are inhabited by more than 700,000 people in an area less than eight kilometers away from the volcano vent. The volcano has been dormant since 1944, but the history of Vesuvius has been punctuated by violent and destructive, albeit infrequent, Plinian‐type explosive eruptions, during which material is continuously ejected at a high velocity and at a great height (up to a few tens of kilometers) from the vent, forming a typical eruptive column with an umbrella cloud. In the past 3500 years, in between one Plinian eruption and the following one, several minor eruptive events have taken place, ranging from subplinian eruptions to more or less violent Strombolian activity and lava flow emissions.

Chronology of Vesuvius? activity from A.D. 79 to 1631 based on archeomagnetism of lavas and historical sources

The activity of Vesuvius between A.D. 79 and 1631 has been investigated by means of precise archaeomagnetic dating of primary volcanic deposits and taking into account the stratigraphy of lavas and tephra, historical written accounts, archaeological evidence related to the developing urbanisation, and radiocarbon ages. We found that the historical records are highly useful in constraining the timing of the main events, even if the data are often too scarce and imprecise for ascertaining the details of all phases of activity, especially their magnitude and emplacement of all the deposit types. In addition, some eruptions that took place in the 9th and 10th centuries appear to be unnoticed by historians. The archaeomagnetic study involved 26 sites of different lavas and 2 pyroclastic deposits. It shows that within the 15 centuries which elapsed between A.D. 79 and 1631, the effusive activity of Vesuvius clustered in the relatively short period of time between A.D. 787 and 1139 and was followed by a 5-century-long repose period. During this time Vesuvius prepared itself for the violent explosive eruption of 1631. The huge lavas shaping the morphology of the coast occurred largely through parasitic vents located outside the Mount Somma caldera. One of these parasitic vents is located at low elevation, very close to the densely inhabited town of Torre Annunziata. Among the various investigated lavas, a number of which were previously attributed to the 1631 eruption, none is actually younger than the 12th century. Therefore it is definitively concluded that the destructive 1631 event was exclusively explosive.

226Ra-excess during the 1631-1944 activity period of Vesuvius (Italy) : A model of alpha-recoil enrichment in a metasomatized mantle and implications on the current state of the magmatic system

The origin of the 226Ra-excess during the last cycle of Vesuvius activity was investigated by high-resolution γ-spectrometry, TIMS and EDXRF. Lavas display high initial 226Ra-excess (500–1000%), similar ( 230Th/ 232Th ) activity ratios (0.87–0.91) and most samples show significant 238U-excess. During the period 1631–1944 the initial absolute 226Ra-excess reached the highest values (19–44 dpm g −1) recorded for earth volcanoes. Crystal fractionation and particularly leucite floating did not cause the 226Ra-excess in spite of the high 226Ra activity (21–85 dpm g −1) in leucite. The presence of phlogopite in the mantle source, documented by field and petrological evidences on local mantle-derived xenoliths, rules out that equilibrium partial melting can be responsible for the 226Ra-excess. This primary feature may be explained by a multistage process involving metasomatic mantle fluids (MMFs) flowing through a mantle wedge where U is concentrated as U-accessory minerals deposited along microfractures. Fluids, passing through the mantle wedge, are supplied of 226Ra, 230Th and 234U by α-decay recoil of parent nuclides from U-enriched microfractures. This model calculates that the ascent time of fluids through the mantle wedge was ≤ 12 ka. Successively MMFs mixed with mantle-derived melts, giving rise to 226Ra-enriched magmas, which entered the Vesuvius plumbing system less than 7 ka. Crystal fractionation did not affect extensively the initial 226Ra/Ba ratio, which varied in the 1631–1944 period according to a pattern reflecting periodic inputs of 226Ra-enriched magma, variable reservoir volumes and residence times in magmatic chamber(s). The temporal trend of the reservoir volumes, extrapolated to the present time, indicates a volume of magma of ∼ 0.021 km 3, stored most probably in a shallow chamber.

On the time-scale invariance of the eruptive activity of Vesuvius

At Vesuvius, the intervals between final effusive eruptions since 1631 AD and those between successive plinian eruptions since 25 000 yr BP follow the same power law, when separately ranked in decreasing order. So, shifts from small to large scales are possible and this might be very helpful for the assessment of hazards of future strong volcanic activity.

Contrasting styles of Mount Vesuvius activity in the period between the Avellino and Pompeii Plinian eruptions, and some implications for assessment of future hazards

Gruppo Nazionale di Vulcanologia (GNV) of the Consiglio Nazionale delle Ricerche (CNR) of Italy

The eruptive activity of Vesuvius and its neural architecture

The Vesuvius volcano is a complex system that shows fractal and turbulent behaviours on short time-scales. To capture the intrinsic non-linear dynamic processes of the volcano on longer time-scales, a hybrid system consisting of an Artificial Neural Network and an Evolutionary Algorithm was applied to the well-documented eruptive activity occurring from 1631 onward. An important result of such an investigation is that the next volcanic activity is very unlikely to occur before 2020.

Violent strombolian and subplinian eruptions at Vesuvius during post-1631 activity

On the basis of historical chronicles and field investigations the tephrostratigraphic sequence of post-1631 activity of Vesuvius is reconstructed. It has been established that, during this period, in addition to numerous totally effusive eruptions and/or normal strombolian activity, 16 explosive events produced well-traceable tephra deposits in the area outside the Mount Somma caldera. Ages of tephra beds were established on the basis of stratigraphic relationships with historical lava flows and comparison with chroniclers information. The dispersal and lithological characteristics of tephra deposits combined with description of explosive activity lead to the identification of three styles: (a) periods of violent strombolian activity; (b) violent strombolian eruptions; and (c) subplinian eruptions. Violent strombolian eruptions and periods of discrete activity are characterized by the formation of lapilli falls from eruptive columns only some kilometers high. Subplinian eruptions are defined on the basis of their lapilli fall volumes which is of the order of 107 m3, on eruptive column heights of approximately 10 km, bt higher than 1.5, and mass discharged rate values not lower than 106 kg/s. During the first century of activity after the 1631 eruption, two periods of violent strombolian activity occurred at Vesuvius (1682–1707 and 1707–1719) preceded, and followed, by a series of violent strombolian eruptions (1660, 1682, 1707, 1723, 1730, 1790, 1872). Between 1730 and 1779 a relevant change in the eruptive style of Vesuvius occurred by an increase in the explosivity of the eruptions. During the past two centuries of activity, only a few eruptions reached subplinian magnitude and only five eruptions had a phreatomagmatic phase (1779, 1794, 1822, 1906, 1944). Therefore, the previously accepted model of cyclic activity, in which each cycle is closed by an important explosive eruption with phreatomagmatic characteristics, is unfounded. The tephrostratigraphy of the 1906 eruption proposed in this work differs substantially from some previous reconstructions, on which the basis for the modeling of Vesuvius’ behavior in this time span was formed.

Experimental determination of aluminous clinopyroxene–melt partition coefficients for potassic liquids, with application to the evolution of the Roman province potassic magmas

We have experimentally determined the partition coefficients of rare earth elements (REE), HFSE (Ti, Zr, Hf, Nb, Ta) and other trace elements between clinopyroxene and potassic silicate melts at 0.1–200 MPa and 1042–1140°C. The major and trace element contents of clinopyroxene and liquid were determined by electron probe and ion microprobe, respectively. The liquidus clinopyroxenes are extremely rich in Al 2O 3 (up to 12%) and Fe 2O 3, which enables us to test suggestions that partition coefficients of HFSE and REE depend on the Al content of the clinopyroxene (e.g., Lundstrom, C.C., Shaw, H.F., Ryerson, F.J., Williams, Q., Gill, J., 1998. Crystal chemical control of clinopyroxene–melt partitioning in the Di–Ab–An system: implications for elemental fractionations in the depleted mantle. Geochim. Cosmochim. Acta 62, 2849–2862.). When compared with previous data for low-alumina clinopyroxene crystallised under similar P– T conditions, the increase in weight partition coefficient D i (=[ I] xtl/[ I] liq) for all the HFSE and REE is dramatic. For Ti and the REE, partition coefficients increase by about one order of magnitude as Al iv concentration of clinopyroxene increases from 0.02 to 0.5. For Nb, Ta and Zr, the effect is even more pronounced, a two order of magnitude increase being found to correspond to this increase in Al iv. We applied the data to model the fractionation of historic lavas from Vesuvius. Previous work using the major elements (Belkin, H.E., Kilburn, C.R.J., DeVivo, B., 1993. Sampling and major element chemistry of the recent (AD 1631–1944) Vesuvius activity. J. Volcanol. Geotherm. Res. 58, 273–290.) indicates a liquid line of descent from trachybasalt to leucite tephrite dominated by clinopyroxene crystallisation. The REE and HFSE concentrations in the lavas are consistent with 40–50% fractional crystallisation of clinopyroxene (accompanied by minor leucite) between the two magmatic endmembers, with partition coefficients for the REE appropriate for clinopyroxenes containing ≤7.5 wt.% Al 2O 3. Pyroxenes of the latter composition are frequent phenocrysts in the lavas and previous experimental work (Dolfi, D., Trigila, R., 1988. Chemical relations between clinopyroxenes and coexisting glasses obtained from melting experiments on alkaline basic lavas. Rend. Soc. Ital. Mineral. Petrol. 43, 1101–1110; Trigila, R., De Benedetti, A.A., 1993. Petrogenesis of Vesuvius historical lavas constrained by Pearce element ratio analysis and experimental phase equilibria. J. Volcanol. Geotherm. Res. 58, 315–343.) implies that they precipitate under very low pressure low water activity conditions, i.e. within the magma chamber at <200 MPa.

The activity of Vesuvius in the next millennium

The time distribution of the historical eruptions of Vesuvius allows the forecasting of the activity of the volcano for the next millennium according to three independent models. The next event with volcanic explosivity index (VEI)=4 is likely to occur during the next few decades followed by a decreasing number of smaller eruptions in the successive few centuries and by a very long period of quiescence up to the beginning of the following fourth millennium when the next Plinian event (VEI=5) might occur.