Effect of degassing on sulfur contents and δ34S values in Somma-Vesuvius magmas

Sulfur contents and δ³⁴S values of Somma-Vesuvius magmas are consistent with syneruptive, open-system degassing at temperatures of 800–850°C for Plinian pumices and 1100–1200°C for lavas. The extent of degassing appears to be greater in lavas than in pumices. The key parameter controlling the ³⁴S/³²S ratio of Somma-Vesuvius volcanics is the average magma oxidation state, which generally varies from 0.85 to 1.20 Δ NNO units for lavas and from 1.20 to 1.40 Δ NNO units for pumices. Consequently, S contents and δ³⁴S values of magmas constitute a potentially valuable tool in estimating their average redox conditions. The results of this study may help in risk mitigation when the Vesuvius magmatic system evolves toward eruptive conditions. Received: 20 January 1998 / Accepted: 5 May 1998     

High frequency strong ground motion modelling in the Catania area associated with the Ibleo-Maltese fault system

A hybrid statistical-deterministic approach has been applied to estimate strong ground motion parameters (PGA, spectral ordinates) in South-Eastern Sicily for a M = 7 earthquake. A number of 100 different rupture processes have been simulated along a composite fault system representing two segments of the Ibleo-Maltese fault scarp. Map at regional scale of mean PGA in the 0.5–20 Hz frequency band shows highest values (0.4–0.5 g) nearby and North of Catania, due to a dominant directivity effect. The COV parameter, which expresses the variability of PGA values as a function of source complexity, is higher in the region nearby and South of the town of Augusta, where, depending on the rupture history, rather large PGA values can be observed (>0.4 g). PGA attenuation curves suggest that an azimuthal variation could be related to the source extent and directivity. The response and pseudo acceleration spectra are computed for different sites in the town of Catania including an approximate 1D site response. Ground motion amplification effects at high frequency (5–20 Hz) are produced by thin shallow layer of soft clay, loose pyroclastites and fill. We observe small amplification effects, in the frequency ranges 2–3 Hz and 5–10 Hz, in sites where recent alluvia reach a thickness of some tens of meters. Otherwise, sites located on outcrops of massive lavas show moderate attenuation.     

Oblique rifting in Salina, Lipari and Vulcano islands (Aeolian islands, southern Italy)

A structural analysis carried out on the volcanic products of the islands of Salina, Lipari and Vulcano (Aeolian archipelago) points out that the large-scale tectonic setting is dominated by NW-SE trending right-lateral extensional strike-slip faults and by N-S to NE-SW trending normal faults and fractures. This fault pattern generates pull-apart type structures, developing between different right-hand overlapping fault segments and a characteristic extensional imbricate fan geometry at the tip of the major strike-slip faults. All the structures, representing the surface expression of an active crustal discontinuity which controls the evolutionary history of the magmatism of the three islands, are kinematically compatible with a N100°E extension related to a rifting process affecting southern Italy.     

Analisi di una serie pluviometrica

Riassunto Applicando l'analisi periodale alle precipitazioni atmosferiche raccolte a Firenze dal 1813 al 1918 si sono trovate onde componenti di anni 35; 30; 28–14; 16; 11; 8; 5,3; 4; 3; 2. Si è stabilito un confronto tra queste componenti e quelle corrispondenti di Trieste, Padova e Mantova. Per mezzo del criterio diSchuster, modificato daStumpff, si sono riscontrate reali le onde di periodo inferiore a 14 anni e superiore a 35 anni.

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Summary By applying the periodal analysis to the rainfall gathered in Florence from the year 1913 to 1918, the component waves of the years 35; 30; 28–14; 16; 11; 8; 5,3; 4; 3; 2 have been found. A comparison between these components and those corresponding of Trieste, Padua and Mantua has been ascertained. ThroughSchuster's Criterion, modified byStumpff, the waves of a period inferior to 14 years and superior to 35 years have proved evident.

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Zummenfassung Bei Anwendung der Periodogrammanalyse an die in den Jahren 1813 bis 1918 in Florenz aufgesammelten atmosphärischen Niederschläge, sind Wellen aus den folgenden Jahren bestehend: 35; 30; 28–14; 16; 11; 8; 5,3; 4; 3; 2 gefunden worden. Es wurde ein Verhältnis zwischen diesen Beständen und den entsprechenden von Triest, Padua und Mantova festgestellt. Auf Grund desSchuster-ischen und vonK. Stumpff berichtigten Kriteriums, wurden die Wellenperioden von unter 14 Jahren und von über 35 Jahren als reellen befunden.

     

On the uniformity of anthropogenic Venice uplift

A programme of Venice uplift because of seawater injection into a 600–800 m deep brackish aquifer underlying the lagoon has recently been advanced. As the actual spatial variability of the hydro‐geological parameters is to a large extent unknown, a controversial issue concerns the 25–30 cm heave prediction with the possible generation of differential displacements that might jeopardize the integrity of the architectural patrimony. It is shown that significant differential displacements have occurred in Venice in the past and are still presently occurring as evidenced by SAR interferometry. The results of a stochastic analysis addressing the variability of the hydraulic conductivity of the injected formation indicate that even a highly uneven aquifer expansion does not migrate to ground surface because of the smoothing effect exerted by the overburden. The predicted differential displacements are well below the values Venice is experiencing. Any a priori alarmism appears to be unfounded and unjustified.     

NGC 3741: the dark halo profile from the most extended rotation curve

We present new H  i observations of the nearby dwarf galaxy NGC 3741. This galaxy has an extremely extended H  i disc, which allows us to trace the rotation curve out to unprecedented distances in terms of the optical disc: we reach 42 B -band exponential scalelengths or about 7 kpc. The H  i disc is strongly warped, but the warp is very symmetric. The distribution and kinematics are accurately derived by building model data cubes, which closely reproduce the observations. In order to account for the observed features in the data cube, radial motions of the order of 5–13 km s⁻¹ are needed. They are consistent with an inner bar of several hundreds of pc and accretion of material in the outer regions.
The observed rotation curve was decomposed into its stellar, gaseous and dark components. The Burkert dark halo (with a central constant density core) provides very good fits. The dark halo density distribution predicted by the Λ cold dark matter (CDM) theory fails to fit the data, unless NGC 3741 is a 2.5σ exception to the predicted relation between concentration parameter and virial mass and at the same time a high value of the virial mass (though poorly constrained) of  10¹¹ M_⊙  . Noticeably, modified Newtonian dynamics (MOND) seems to be consistent with the observed rotation curve. Scaling up the contribution of the gaseous disc also gives a good fit.     

Shallow magma transport for the 2002–3 Mt. Etna eruption inferred from thermal infrared surveys

The 26 October 2002–28 January 2003 eruption of Mt. Etna volcano was characterised by lava effusion and by an uncommon explosivity along a 1 km-long-eruptive fissure on the southern, upper flank of the volcano. The intense activity promoted rapid growth of cinder cones and several effusive vents. Analysis of thermal images, recorded throughout the eruption, allowed investigation of the distribution of vents along the eruptive fissure, and of the nature of explosive activity. The spatial and temporal distribution of active vents revealed phases of dike intrusion, expansion, geometric stabilization and drainage. These phases were characterised by different styles of explosive activity, with a gradual transition from fire fountaining through transitional phases to mild strombolian activity, and ending with non-explosive lava effusion. Here we interpret the mechanisms of the dike emplacement and the eruptive dynamics, according to changes in the eruptive style, vent morphology and apparent temperature variations at vents, detected through thermal imaging. This is the first time that dike emplacement and eruptive activity have been tracked using a handheld thermal camera and we believe that its use was crucial to gain a detailed understanding of the eruptive event.     

Out‐of‐plane seismic behaviour of rocking masonry walls

The evaluation of the out‐of‐plane behaviour of unreinforced walls is one of the most debated topics in the seismic assessment of existing masonry buildings. The discontinuous nature of masonry and its interaction with the remainder of the building make the dynamic modelling of out‐of‐plane response troublesome. In this paper, the results of a shaking table laboratory campaign on a tuff masonry, natural scale, U‐shaped assemblage (façade adjacent to transverse walls) are presented. The tests, excited by scaled natural accelerograms, replicate the behaviour of external walls in existing masonry buildings, from the beginning of rocking motion to overturning. Two approaches have been developed for modelling the out‐of‐plane seismic behaviour: the discrete element method and an SDOF analytic model. Both approaches are shown to be capable of reproducing the experimental behaviour in terms of maximum rotation and time history dynamic response. Finally, test results and numerical time history simulations have been compared with the Italian seismic code assessment procedures. Copyright © 2011 John Wiley & Sons, Ltd.     

The Meteoritical Bulletin,No. 93, 2008 March

Abstract— In this edition of the Meteoritical Bulletin, 1443 approved meteorite names with their relevant data are reported, one from a specific location within Africa, 211 from Northwest Africa, 5 from KOREAMET, 598 from the Chinese Antarctic Expedition, 23 from the Americas, 151 from Asia, three from Australia, two from Europe, two from NOVA, and 447 from ANSMET that were not reported in the Meteoritical Bulletin no. 87. Also reported are 4 falls from the Americas. Some highlights of approved meteorites are 10 lunar (including NWA 5000, an 11.528 kg sample), 3 Martian, 4 irons (one from Indonesia), 2 ureilites, 5 mesosiderites, 1 pallasite, 6 brachinites, 3 CV3s, 4 CO3s, 8 CMs, 12 CK3s, and many more. Finally, the Committee on Nomenclature of the Meteoritical Society announces two new names series in North America.