Evaluation of local amplification in the seismic microzonation: comparison between punctual multidisciplinary integrated studies and macroseismic methods in Fivizzano's area (Toscana, Italy)

In the seismic microzonation the evaluation of the local amplification issue may be solved using different methodological approaches. Taking the hint from the studies made within VEL project framework, sponsored by Tuscany Region on Fivizzano's area we are herewith comparing the results of geotechnical and geophysical integrated multidisciplinary studies with the existing data available from previous studies, mainly using a macroseismic approach, on the same area. This qualitative method does not seem to be able to make any forecasting on the scale whereas generally microzoning is performed. On the contrary, the knowledge of the geological-technical model of the investigated area, obtained by punctual multidisciplinary integrated studies, allows a direct collection of the data to insert in input step of numerical modelling, aimed to local effects evaluation. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Hyblean xenolith suite (Sicily): an unexpected legacy of the Ionian–Tethys realm

The extensive study of a great number of deep-seated xenoliths from Tortonian tuff-breccia pipes in the Hyblean area (Sicily) revealed the following fundamental evidence: (1) typical continental crust rocks are completely absent in the entire xenolith suite; (2) mantle ultramafics are more abundant than gabbroids; (3) sheared oxide–gabbros, closely resembling those from oceanic fracture zones, are relatively common; (4) secondary mineral assemblages, compatible with alteration processes in serpentinite-hosted hydrothermal systems, occur both in peridotites and gabbros. Among the products of this hydrothermal activity, organic compounds, having abiotic origin via Fischer–Tropsch synthesis, occur in some hydrothermally altered gabbro and ultramafic xenoliths, as well as in hydrothermal clays. Moreover, the U–Pb dating of hydrothermal zircon grains, hosted in a xenolith of metasomatized tectonic breccia, indicated an Early–Middle Triassic age of the fossil hydrothermal system. Another line of evidence for the oceanic nature of the Hyblean–Pelagian basement is the complete absence of continental crust lithologies (granites, felsic metaigneous, and metasedimentary rocks) in outcrops and in boreholes, and the oceanic affinity of the Tertiary volcanic rocks from the Hyblean Plateau and the Sicily Channel (Pantelleria and Linosa Islands), which lack of any geochemical signature for continental crust contamination. A reappraisal of existing geophysical data pointed out that serpentinites form the dominant lithologies in the lithospheric basement of the Hyblean–Pelagian area down to a mean depth of 19 km, which represents the regional Moho considered as the serpentinization front, marking the transition from serpentinites to unaltered peridotites. On these grounds, we confirm that Hyblean xenoliths contain mineralogical, compositional, and textural evidence for tectonic, magmatic, and hydrothermal processes indicating the existence of fossil oceanic core complexes, in the geotectonic framework of the Paleo–Mesozoic, ultra-slow spreading, Ionian–Tethys Ocean forming the present Ionian–Hyblean–Pelagian domain.     

The European Atlas of the Seas: Relating Natural and Socio-Economic Elements of Coastal and Marine Environments in the European Union

The European Atlas of the Seas is a web-based information system aimed at the general public, but it is also capable of supporting selected nonspecialist professionals in addressing environmental issues, human activities, and policies related to the coast and sea. It includes a collection of maps and associated fact sheets based on data originating primarily from the European Commission and its agencies, which present a snapshot of key natural and socio-economic elements of the coastal and marine regions of the European Union. It provides a suite of basic instruments for map analysis and data combination to derive ad hoc maritime indicators.     

Interferometric millimeter observations of water vapor on Mars and comparison with Mars Express measurements

We present interferometric mapping of the 225.9-GHz HDO and 203.4-GHz lines on Mars obtained with the IRAM Plateau de Bure facility (PdBI). The observations were performed during martian year 28 (MY28), at L_s=320.3° for the HDO line, and at L_s=324.3° for the line. The HDO line is detected at the eastern (morning) and western (evening) limbs of the northern hemisphere, corresponding to a water column density in the range 3-6 pr.-μm. The line is not detected, which is compatible with the column densities derived from the HDO line. Quasi-simultaneous far infrared measurements obtained by the Planetary Fourier Spectrometer (PFS) onboard the Mars Express spacecraft confirm our PdBI results, yielding a 5±1 pr.-μm meridionally constant water column abundance.Such a low water abundance during the southern mid-autumn of MY28 does not correspond to the standard martian climatology as observed during the previous years. It was however already retrieved from near-infrared observations performed by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard the Mars Reconnaissance Orbiter spacecraft [Smith, M.D., Wolff, M.J., Clancy, R.T., Murchie, S.L. 2009. CRISM observations of water vapor and carbon monoxide. J. Geophys. Res. 114, doi: 10.1029/2008JE003288]. Our observations thus confirm that the planet-encircling dust storm that occurred during MY28 significantly affected the martian water cycle. Our observations also demonstrate the usefulness of interferometric submillimeter observations to survey the martian water cycle from ground-based facilities.     

Zero-population stars

The expected characteristics of stars with zero metal content are investigated for a large range of masses and in varying the original helium-content. It is shown that, in such an extreme case (Z=0), the Main Sequence locus is much less sensitive than expected to the He-content;Y=0 models are found to ignite 3α reactions in the Zero-Age Main Sequence at masses larger by ～ 5M _⊙ than in theY=0.2 case. A comparison with previous results discloses the M.S. slope to be a sensitive function of the metal content only. Evolutionary computations confirm that possible survivors of the zero population can develop a giant branch, akin to that of the well-known Population II stars.     

Assessment of a 2016 mission concept: The search for trace gases in the atmosphere of Mars

The reported detection of methane in the atmosphere of Mars as well as its potentially large seasonal spatial variations challenge our understanding of both the sources and sinks of atmospheric trace gases. The presence of methane suggests ongoing exchange between the subsurface and the atmosphere of potentially biogenic trace gases, while the spatial and temporal variations cannot be accounted for with current knowledge of martian photochemistry. A Joint Instrument Definition Team (JIDT) was asked to assess concepts for a mission that might follow up on these discoveries within the framework of a series of joint missions being considered by ESA and NASA for possible future exploration of Mars. The following is based on the report of the JIDT to the space agencies (Zurek et al., 2009); a synopsis of the report was presented at the Workshop on Mars Methane held in Frascati, Italy, in November 2009. To summarize, the JIDT believed that a scientifically exciting and credible mission could be conducted within the evolving capabilities of the science/telecommunications orbiter being considered by ESA and NASA for possible launch in the 2016 opportunity for Mars.     

Primordial non-Gaussianity: local curvature method and statistical significance of constraints on fNL from WMAP data

We test the consistency of estimates of the non-linear coupling constant f _NL using non-Gaussian cosmic microwave background (CMB) maps generated by the method described in the work of Liguori, Matarrese & Moscardini. This procedure to obtain non-Gaussian maps differs significantly from the method used in previous works on the estimation of f _NL. Nevertheless, using spherical wavelets, we find results in very good agreement with Mukherjee & Wang, showing that the two ways of generating primordial non-Gaussian maps give equivalent results. Moreover, we introduce a new method for estimating the non-linear coupling constant from CMB observations by using the local curvature of the temperature fluctuation field. We present both Bayesian credible regions (assuming a flat prior) and proper (frequentist) confidence intervals on f _NL, and discuss the relation between the two approaches. The Bayesian approach tends to yield lower error bars than the frequentist approach, suggesting that a careful analysis of the different interpretations is needed. Using this method, we estimate   f _NL=−10⁺²⁷⁰₋₂₆₀  at the 2σ level (Bayesian) and   f _NL=−10⁺³¹⁰₋₂₇₀  (frequentist). Moreover, we find that the wavelet and the local curvature approaches, which provide similar error bars, yield approximately uncorrelated estimates of f _NL and therefore, as advocated in the work of Cabella et al., the estimates may be combined to reduce the error bars. In this way, we obtain   f _NL=−5 ± 85  and   f _NL=−5 ± 175  at the 1σ and 2σ level respectively using the frequentist approach.     

On the evolutionary stage of stars in the Draco dwarf Galaxy

An analysis of the colour-magnitude diagram of stars in Draco dwarf Galaxy is performed on the basis of Baade and Swope observational results. Some evidence is found for the occurrence of a clump in the luminosity distribution of Red Giants stars. By combining this characteristic with the morphology of Horizontal Branch one obtains — in the frame of present knowledge of star-evolution —a suggestion for accepting high helium content (Y-0.30) with a relatively small age (1–2×10⁹ yr) for the evolving stars.Some correlations among lifetimes of evolutionaries stages are derived.

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Sommario Sulla base dei risultati osservativi di Baade e Swope viene eseguita un'analisi del diagramma colore-magnitudine delle stelle della Galassia Nana in Draco. Viene così evidenziata la possibile esistenza di un picco nella distribuzione in luminosità delle Giganti Rosse. Combinando questa caratteristica con l'osservato andamento del Ramo Orizzontale si mostra come — nell'ambito delle attuali conoscenze sull'evoluzione stellare — un simile comportamento conduca a postulare un alto contenuto di elio (Y-0.30) e una età relativamente bassa (1–2×10⁹ anni) per le stelle del sistema.Sono infine ricavate alcune correlazioni, tra le vite medie delle principali fasi evolutive.

     

L'anticlinale gravimetrica di Fontevivo: Un confronto fra i risultati di due diversi metodi di gravimetria

Riassunto Sono posti a confronto i risultati del rilevamento gravimetrico della zona di Fontevivo (Parma) eseguiti prima con bilancia di torsione e successivamente con gravimetro (tipc Humble-Truman); ottenendosi un buon accordo fra i due metodi.

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Zusammenfassung Vergleich der Ergebnisse der gravimetrischen Aufnahme von der Umgebung von Fontevivo (Parma), zuerst mit der Drehwaage durchgeführt, nachher mit einem Gravimeter nach Humble-Truman; die Übereinstimmung der Ergebnisse ist befriedigend.

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Résumé Comparaison des résultats du levé gravimétrique de la zone de Fontevivo (Parme) effectué d'abord avec la balance de torsion, ensuite avec un gravimètre type Humble-Truman; bonne concordance entre les deux méthodes.