Seismic hazard in southern Calabria (Italy) based on the analysis of a synthetic earthquake catalog     

Rodolfo Console  Massimo Chiappini  Liliana Minelli  Fabio Speranza  Roberto Carluccio  Michele Greco 《Acta Geophysica》2018,66(5):931-943

The application of a newly developed physics-based earthquake simulator to the active faults inferred by aeromagnetism in southern Calabria has produced a synthetic catalog lasting 100 ky including more than 18,000 earthquakes of magnitude ≥?4.0. This catalog exhibits temporal, spatial and magnitude features, which resemble those of the observed seismicity. As an example of the potential use of synthetic catalogs, a map of the peak ground acceleration (PGA) for a given exceedance probability on the territory under investigation has been produced by means of a simple attenuation law applied to all the events reported in the synthetic catalog. This map was compared with the existing hazard map that is presently used in the national seismic building regulations. The comparison supports a strong similarity of our results with the values given in the present Italian seismic building code, despite the latter being based on a different methodology. The same similarity cannot be recognized for the comparison of our present study with the results obtained from a previous study based on our same methodology but with a different geological model.  相似文献   

Meteorites from the Lut Desert (Iran)     

Hamed Pourkhorsandi  Jrme Gattacceca  Pierre Rochette  Massimo D'Orazio  Hojat Kamali  Roberto de Avillez  Sonia Letichevsky  Morteza Djamali  Hassan Mirnejad  Vinciane Debaille  A. J. Timothy Jull 《Meteoritics & planetary science》2019,54(8):1737-1763

We present for the first time a detailed report on the discovery of a new meteorite collection region in the Lut Desert, eastern–southeastern Iran, describing its geological, morphological, and climatic setting. Our search campaigns, alongside with the activity of meteorite hunters, yielded >200 meteorite finds. Here, we report on their classification, spatial distribution, and terrestrial weathering. All the collected meteorites are ordinary chondrites (OCs). The most abundant by far are the highly weathered paired H5 distributed in the northwest of Kalut area (central Lut, Kerman dense collection area). The second are well‐preserved paired L5 also found in Kalut region. A detailed study of the geochemistry and mineralogy of selected meteorites reveals significant effects of terrestrial weathering. Fe,Ni metal (hereafter simply metal) and troilite are transformed into Fe oxyhydroxides. A rather unusual type of troilite weathering to pyrite/marcasite is observed in most of the Lut Desert meteorites. Magnetic measurements and X‐ray diffractometry confirm the occurrence of terrestrial weathering products, with the dominance of maghemite, goethite, and hematite. Mobile elements, such as Li, Sr, Mo, Ba, Tl, Th, and U, are enriched with respect to fresh falls. Meanwhile, a decrease in the V, Cr, Co, Rb (and possibly Fe) due to terrestrial weathering is detectable. The total carbon and CaCO₃ is higher than in samples from other hot deserts. The weathering effects observed in the Lut Desert OCs can be used as distinctive indicators to distinguish them from meteorites from other regions of the Earth. Measurements of terrestrial age (¹⁴C) show a range of 10–30 ka, which is in the range of ages reported for meteorites from other hot deserts except the Atacama Desert (Chile). Considering the high potential of the Lut Desert in meteorite preservation, systematic works should lead to the discovery of more samples giving access to interesting material for future studies.  相似文献   

Laboratory measurements of super-resolving Toraldo pupils for radio astronomical applications     

Luca Olmi  Pietro Bolli  Luca Cresci  Francesco D’Agostino  Massimo Migliozzi  Daniela Mugnai  Enzo Natale  Renzo Nesti  Dario Panella  Lorenzo Stefani 《Experimental Astronomy》2017,43(3):285-309

The concept of super-resolution refers to various methods for improving the angular resolution of an optical imaging system beyond the classical diffraction limit. Although several techniques to narrow the central lobe of the illumination Point Spread Function have been developed in optical microscopy, most of these methods cannot be implemented on astronomical telescopes. A possible exception is represented by the variable transmittance filters, also known as “Toraldo Pupils” (TPs) since they were introduced for the first time by G. Toraldo di Francia in 1952 (Toraldo di Francia, Il Nuovo Cimento (Suppl.) 9, 426, 1952). In the microwave range, the first successful laboratory test of TPs was performed in 2003 (Mugnai et al. Phys. Lett. A 311, 77–81, 2003). These first results suggested that TPs could represent a viable approach to achieve super-resolution in Radio Astronomy. We have therefore started a project devoted to a more exhaustive analysis of TPs, in order to assess their potential usefulness to achieve super-resolution on a radio telescope, as well as to determine their drawbacks. In the present work we report on the results of extensive microwave measurements, using TPs with different geometrical shapes, which confirm the correctness of the first experiments in 2003. We have also extended the original investigation to carry out full-wave electromagnetic numerical simulations and also to perform planar scanning of the near-field and transform the results into the far-field.  相似文献   

Modification of REE distribution of ordinary chondrites from Atacama (Chile) and Lut (Iran) hot deserts: Insights into the chemical weathering of meteorites          下载免费PDF全文

Hamed Pourkhorsandi  Massimo D'Orazio  Pierre Rochette  Millarca Valenzuela  Jérôme Gattacceca  Hassan Mirnejad  Brad Sutter  Aurore Hutzler  Maria Aboulahris 《Meteoritics & planetary science》2017,52(9):1843-1858

The behavior of rare earth elements (REEs) during hot desert weathering of meteorites is investigated. Ordinary chondrites (OCs) from Atacama (Chile) and Lut (Iran) deserts show different variations in REE composition during this process. Inductively coupled plasma–mass spectrometry (ICP‐MS) data reveal that hot desert OCs tend to show elevated light REE concentrations, relative to OC falls. Chondrites from Atacama are by far the most enriched in REEs and this enrichment is not necessarily related to their degree of weathering. Positive Ce anomaly of fresh chondrites from Atacama and the successive formation of a negative Ce anomaly with the addition of trivalent REEs are similar to the process reported from Antarctic eucrites. In addition to REEs, Sr and Ba also show different concentrations when comparing OCs from different hot deserts. The stability of Atacama surfaces and the associated old terrestrial ages of meteorites from this region give the samples the necessary time to interact with the terrestrial environment and to be chemically modified. Higher REE contents and LREE‐enriched composition are evidence of contamination by terrestrial soil. Despite their low degrees of weathering, special care must be taken into account while working on the REE composition of Atacama meteorites for cosmochemistry applications. In contrast, chondrites from the Lut desert show lower degrees of REE modification, despite significant weathering signed by Sr content. This is explained by the relatively rapid weathering rate of the meteorites occurring in the Lut desert, which hampers the penetration of terrestrial material by forming voluminous Fe oxide/oxyhydroxides shortly after the meteorite fall.  相似文献   

Ecotoxicological and human health risk in a petrochemical district of southern Italy   总被引：2，自引：0，他引：2  

Ausili A  Gabellini M  Cammarata G  Fattorini D  Benedetti M  Pisanelli B  Gorbi S  Regoli F 《Marine environmental research》2008,66(1):215-217

An ecotoxicological investigation has been carried in the petrochemical district of Priolo (Sicily, Italy), one of the largest in Europe. Results indicated a severe mercury contamination in sediments sampled near a chloro-alkali plant. A clear bioavailability of this element was demonstrated in mussels Mytilus galloprovincialis (both native and translocated) and the benthic fish Mullus barbatus, which also exhibited marked genotoxic damages. The elevated mercury concentrations in marine organisms are a serious concern for human health; according to the national average fish consumption, the provisional tolerable weekly intake (PTWI) of Hg would be easily exceeded by at least 4 to 12 fold. Such toxicological risk is of particular importance for pregnant women, being possibly involved in the elevated frequency of neonatal malformations.  相似文献   

Comparing Beerkan infiltration tests with rainfall simulation experiments for hydraulic characterization of a sandy‐loam soil          下载免费PDF全文

Simone Di Prima  Vincenzo Bagarello  Laurent Lassabatere  Rafael Angulo‐Jaramillo  Inmaculada Bautista  Maria Burguet  Artemi Cerdà  Massimo Iovino  Massimo Prosdocimi 《水文研究》2017,31(20):3520-3532

Saturated soil hydraulic conductivity, K _s , data collected by ponding infiltrometer methods and usual experimental procedures could be unusable for interpreting field hydrological processes and particularly rainfall infiltration. The K _s values determined by an infiltrometer experiment carried out by applying water at a relatively large distance from the soil surface could however be more appropriate to explain surface runoff generation phenomena during intense rainfall events. In this study, a link between rainfall simulation and ponding infiltrometer experiments was established for a sandy‐loam soil. The height of water pouring for the infiltrometer run was chosen, establishing a similarity between the gravitational potential energy of the applied water, E _p , and the rainfall kinetic energy, E _k . To test the soundness of this procedure, the soil was sampled with the Beerkan estimation of soil transfer parameters procedure of soil hydraulic characterization and two heights of water pouring (0.03 m, i.e., usual procedure, and 0.34 m, yielding E _p  = E _k ). Then, a comparison between experimental steady‐state infiltration rates, i _sR , measured with rainfall simulation experiments determining runoff production and K _s values for the two water pouring heights was carried out in order to discriminate between theoretically possible (i _sR  ≥ K _s ) and impossible (i _sR  < K _s ) situations. Physically possible K _s values were only obtained by applying water at a relatively large distance from the soil surface, because i _sR was equal to 20.0 mm h^?1 and K _s values were 146.2–163.9 and 15.2–18.7 mm h^?1 for a height of water pouring of 0.03 and 0.34 m, respectively. This result suggested the consistency between Beerkan runs with a high height of water pouring and rainfall simulator experiments. Soil compaction and mechanical aggregate breakdown were the most plausible physical mechanisms determining reduction of K _s with height. This study demonstrated that the height from which water is poured onto the soil surface is a key parameter in infiltrometer experiments and can be adapted to mimic the effect of high intensity rain on soil hydraulic properties.  相似文献   

Evidence of a shallow magma intrusion beneath the NE Rift system of Mt. Etna during 2013          下载免费PDF全文

Valentina Bruno  Carmelo Ferlito  Mario Mattia  Carmelo Monaco  Massimo Rossi  Danila Scandura 《地学学报》2016,28(5):356-363

Continuous GPS (CGPS) data, collected at Mt. Etna between April 2012 and October 2013, clearly define inflation/deflation processes typically observed before/after an eruption onset. During the inflationary process from May to October 2013, a particular deformation pattern localised in the upper North Eastern sector of the volcano suggests that a magma intrusion had occurred a few km away from the axis of the summit craters, beneath the NE Rift system. This is the first time that this pattern has been recorded by CGPS data at Mt. Etna. We believe that this inflation process might have taken place periodically at Mt. Etna and might be associated with the intrusion of batches of magma that are separate from the main feeding system. We provide a model to explain this unusual behaviour and the eruptive regime of this rift zone, which is characterised by long periods of quiescence followed by often dangerous eruptions in which vents can open at low elevation and thus threaten the villages in this sector of the volcano.  相似文献   

‘Isolated base-of-slope aprons’: An oxymoron for shallow-marine fan-shaped,temperate-water,carbonate bodies along the south-east Salento escarpment (Pleistocene,Apulia, southern Italy)     

Marcello Tropeano  Luigi Spalluto  Demetrio Meloni  Massimo Moretti  Luisa Sabato 《Sedimentology》2022,69(1):345-371

This paper regards the lower Pleistocene temperate-water carbonate deposits disconformably overlying an escarpment made up of faulted Cretaceous to Miocene limestones of the Apulia Foreland (southern Italy). Study deposits discontinuously crop out along the present-day eastern Salento sea cliff, and form isolated fan-shaped bodies, up to 1 km wide and up to 40 to 50 m thick, each of them covering an area of a few square kilometres. The internal arrangement of beds is represented by up to 25° to 30° lobate, seaward dipping clinobeds thinning and onlapping onto a rocky foreslope in the proximal sector and passing to gently inclined to sub-horizontal strata in the distal sector. Seven facies were distinguished, mainly composed of coarse-grained skeletal carbonates made up of a heterozoan association including coralline algae, large and small benthic foraminifera, echinoids, molluscs, bryozoans and serpulids. Since clinobeds were formed thanks to hyperconcentrated density flows (grain flows) bypassing the upper part of the inherited escarpment, these skeletal grains represent ex situ deposits whose shallow-marine factory was located upward (landward) with respect to the bypassed zone, likely in the almost flat area on top of the Salento Peninsula. Clinobeds are often affected by tens of metres wide and long channel-like structures interpreted as landslide scars. Inside these gullies, contorted beds (slumps) or matrix-supported intra-bioclastic floatstone/rudstone (massive deposits) are present. The occurrence of supercritical-flow structures (for example, backset-bedded beds) indicates the development of hydraulic jumps along the steep slope of gullies. Since these clinostratified, fan-shaped carbonate bodies represent carbonate slopes, and that the latter are known as aprons, normally related to linear sourced sediments, an acceptable oxymoron for studied fan-shaped carbonate bodies is suggested: ‘isolated base-of-slope aprons’.  相似文献   

High crustal diversity preserved in the lunar meteorite Mount DeWitt 12007 (Victoria Land,Antarctica)          下载免费PDF全文

Alberto Collareta  Massimo D'Orazio  Maurizio Gemelli  Andreas Pack  Luigi Folco 《Meteoritics & planetary science》2016,51(2):351-371

The meteorite Mount DeWitt (DEW) 12007 is a polymict regolith breccia mainly consisting of glassy impact‐melt breccia particles, gabbroic clasts, feldspathic clasts, impact and volcanic glass beads, basaltic clasts, and mingled breccia clasts embedded in a matrix dominated by fine‐grained crystals; vesicular glassy veins and rare agglutinates are also present. Main minerals are plagioclase (typically An_>85) and clinopyroxene (pigeonites and augites, sometimes interspersed). The presence of tranquillityite, coupled with the petrophysical data, the O‐isotope data (Δ¹⁷O = ?0.075), and the FeO_tot/MnO ratios in olivine (91), pyroxene (65), and bulk rock (77) indicate a lunar origin for DEW 12007. Impactites consist of Al‐rich impact‐melt splashes and plagioclase‐rich meta‐melt clasts. The volcanic products belong to the very low titanium (VLT) or low titanium (LT) suites; an unusual subophitic fragment could be cryptomare‐related. Gabbroic clasts could represent part of a shallow intrusion within a volcanic complex with prevailing VLT affinity. DEW 12007 has a mingled bulk composition with relatively high incompatible element abundances and shows a high crustal diversity comprising clasts from the Moon's major terranes and rare lithologies. First‐order petrographic and chemical features suggest that DEW 12007 could be launch‐paired with other meteorites including Y 793274/981031, QUE 94281, EET 87521/96008, and NWA 4884.  相似文献   

Geochronological study of zircons from continental crust rocks in the Frido Unit (southern Apennines)     

Salvatore Laurita  Giacomo Prosser  Giovanna Rizzo  Antonio Langone  Massimo Tiepolo  Alessandro Laurita 《International Journal of Earth Sciences》2015,104(1):179-203

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