Seismic behaviour of girder bridges for horizontally propagating waves

The results obtained from a parametric study on the influence of horizontally propagating waves for the earthquake behaviour of continuous girder bridges are presented. The investigation is performed for floating-supported bridges excited by an earthquake acting in their vertical planes. The shallow foundations are assumed to be supported on the surface of either a visco-elastic halfspace or a visco-elastic layer resting on an elastic halfspace. Steady-state response for harmonic excitation and transient response for an artificial time history are investigated. Approximate equations describing the influence of horizontally propagating waves are presented and criteria are derived indicating when an increase of the internal forces and of the relative motion between the girder and the abutments can be expected.     

Heuristic considerations pertaining to hailstone size distributions in the plain of Friuli-Venezia Giulia

In this work, the hailstone size distributions at the ground in the plain of Friuli-Venezia Giulia are presented, as revealed through a network of polystyrene pads (hailpads), managed by volunteers, which has been active since 1988. The aim of this work is to highlight possible differences in the diurnal and seasonal behavior of hail at the ground, both from Friuli-Venezia Giulia and other countries, in order to improve the knowledge of this meteorological phenomenon.In the comparison between different countries, differences are found between the yearly size distributions of Friuli-Venezia Giulia and those of North-East Colorado, measured during the National Hail Research Experiment (NHRE). The size distributions obtained in South West France and in Friuli-Venezia Giulia are quite similar and they are slightly different from those of the Grossversuch experiment.In the comparison between different periods of the year, relevant differences are found between April and May and the other months. In particular, thunderstorms are less efficient in producing big hailstones during the former months. The most prolific month in producing hailstones is June, followed by September. This feature is interpreted as due to a form of synergy between the frequency of the synoptic forcing of storms and the amount of available energy at the ground.Analyzing the size distributions at different times of the day, the greatest differences are found in the intervals [00–06] and [06–12] in local time (respectively, [22–04] and [04–10] in UTC). These differences cannot be ascribed to the melting of the hailstones during their fall.     

Fluid geochemistry of the Mondragone hydrothermal systems (southern Italy): water and gas compositions vs. geostructural setting

International Journal of Earth Sciences - The geochemistry of natural thermal fluids discharging in the Mondragone Plain has been investigated. Thermal spring emergences are located along the...     

Two-mica and tourmaline leucogranites from the Everest–Makalu region (Nepal–Tibet). Himalayan leucogranite genesis by isobaric heating?

In the Higher Himalaya of the region from Cho Oyu to the Arun valley northeast of Makalu, the Miocene leucogranites are not hosted only in the upper High Himalayan Crystallines (HHC); a network of dykes also cuts the lower HHC and the Lesser Himalayan Crystallines (LHC).

The plutons and dykes are mainly composed of two-mica (muscovite+biotite±tourmaline±cordierite±andalusite±sillimanite) leucogranite, with tourmaline≤2.6% and biotite>1.5% modal, and tourmaline (muscovite+tourmaline±biotite±sillimanite ±garnet±kyanite±andalusite±spinel±corundum) leucogranite, with tourmaline>2.2% and biotite<1.5% modal.

Both leucogranite types were produced by partial melting in the andalusite–sillimanite facies series, under LP/HT conditions constrained by the occurrence of peritectic andalusite and cordierite. The geochemical features of the leucogranites suggest that tourmaline leucogranite was produced by muscovite dehydration melting in muscovite-rich metapelites at P350 MPa and T≥640°C, whereas two-mica leucogranite was produced by biotite dehydration melting in biotite-rich metapelites at P300 MPa and T≥660–710 °C.

Melting in fertile muscovite-rich metapelites of the top of both the HHC and LHC produced magmas which were emplaced at the same structural level in which they had been generated. Melting in the biotite-rich gneiss of both the HHC and LHC produced hotter magmas which were transported upwards by dyking and eventually coalesced in the plutons of the upper HHC. A similar process also produced a network of two-mica granite at the top of the LHC in the Ama Drime–Nyönno Ri Range northeast of Makalu.

The prograde character of leucogranite melt-producing reactions in the Everest–Makalu area suggests that, here, the generation of Miocene leucogranites took place in a regime of nearly isobaric heating following nearly adiabatic decompression.     

Typology of detrital zircon as a key to unravelling provenance in rift siliciclastic sequences (Permo-Carboniferous of Spiti,N India)

Abstract

Detrital zircon populations from Carboniferous to Permian sandstones from the Lozar Section of Spiti, northern India, were analyzed with the typology method in order to obtain complementary information on the source areas of the sediments. Zircon grains were subdivided into several groups and subgroups, according to degree of abrasion and morphological features.

First appearance of detrital zircons with distinct typologic signature within successive stratigraphic intervals provided useful data about the tectono-magmatic evolution of the northern Indian margin during Late Paleozoic rifting of Gondwana and initial opening of Neotethys. The base of the studied sequence (Lower Carboniferous Thabo Fm.) is characterized by a largely cratonic provenance, seemingly from the Indian Shield to the South. In the Upper Carboniferous Chichong Fm., first occurrence of typical zircons from anatectic granites and increasing abundance of granitoid detritus suggest rapid uplift and unroofing of anatectic rocks of probable Cambro-Ordovician age. In the lowermost Permian (Asselian) glaciomarine Ganmachidam Diamictite, euhedral detrital zircons with peculiar features, associated with Cr-rich chromian spinels and mafic to felsic volcanic rock fragments, hint at emplacement of bimodal alkaline magmatic suites. The same sources, possibly including subvolcanic bodies, continued to be eroded until final break-up, documented by the Permian Kuling Group.     

3D geoelectric tomography and archaeological applications1

Following a previous paper in which the principles of a 3D ground-surface tomographic processing of self-potential data were established, we extend the method to active source geoelectric surveying. The main purpose of the new tomographic approach is to obtain a physical image reconstruction of the induced electric charges distributed over buried resistivity discontinuities. The information is produced in a probabilistic sense, as the mathematical formulation underlying the method treats only the intrinsic physical nature of the generated electric field underground and the method of its ground-surface detection, independently of the geometry of the unknown structures. In practice, a 3D tomography is realized by cross-correlating a set of distributed electric-field ground-surface data with a scanning function, representing a unit positive point charge located anywhere in the lower half-space. The resolution of the method is tested on the synthetic response of a 3D structural simulation of an archaeological target, consisting of an infinitely resistive prismatic body immersed in a half-space, including surface inhomogeneities and layering. Finally, the field response of a 3D structure consisting of a hypogeal dromos-chamber tomb inside the Sabine Necropolis at Colle del Forno, close to Rome, is presented and discussed.     

The Role of Data Processing and Uncertainty Management in Seismic Hazard Evaluations: Insights from Estimates in the Garfagnana–Lunigiana Area (Northern Italy)

Significantly different estimates of seismic hazard may result for the same site as aneffect of different methodological choices underlying the adopted procedures. In orderto explore this aspect, two approaches devoted to probabilistic seismic hazard assessment are considered for the evaluation of hazard in a seismic area in Northern Italy. In particular, results of a standard procedure are compared with those obtained by an innovative approach. Fundamental features of this last methodology are the extensive use of intensity data relative to seismic effects observed at the site of interest during past earthquakes and the basic role attributed to the parameterisation of uncertainty which affects the considered pieces ofinformation. The analysis indicates that the new approach supplies results significantlydifferent from those obtained from standard methodology and that these differences strongly depend on strategies adopted for data processing and for the management of uncertainties which affect input parameters.     

History of the Long Series of Daily Air Temperature in Padova (1725–1998)

The history of the origin of the study of meteorology in Padova and its connection to the major developments of this science in Italy and the international context are presented. Special topics are: the scientific legacy of Galileo Galilei and the Accademia del Cimento,the birth of the first meteorological networks, i.e., Ferdinand II and Leopold de' Medici who created the Rete Medicea, J. Jurin and the network of the RoyalSociety, London, L. Cotte and the Société Royale de Médicine, Paris, J. J. Hemmerand the Societas Meteorologica Palatina, Mannheim. After outliningthe cultural background that favoured the development of meteorology, emphasis is given to the plurisecular time series of meteorological observations, taken in Padova since 1725, in its national and international context. This long series includes barometric pressure, air temperature, wind direction and speed; state of the sky and occurrence of meteorological events and precipitation. Special reference is made to indoor and outdoor temperature observations. Solar radiation falling on each exposure has been modelled in order to know when data were fully reliable and when they were less so. A vertical profile of air temperature has allowed corrections of the change of instrument level, when necessary. In terms of homogeneity, the series can be divided into several periods, during which instruments and operational methods, position, general criteria were unchanged: origins in homes of the first observers (1725–1767); the First Period at the Specola(1768–1812); the Second Period at the Specola (1813–1864); the Third and Fourth Periodsat the Specola (1865–1937); the Last Measurements at theSpecola (1938–1962); the Giovanni Magrini Observatoryof the Water Magistrate (1920–today); the Gino Allegri Airport(1926–1990), the Botanical Gardens (1980–today), the CNR (1984–1986; 1993–today). The latestperiod with the birth of new weather stations, is the most affected byanthropic effect. The simultaneous presence of an urban and a rural weather station pointed out local effects which dominate the urban heat island.     

EXOTIME: searching for planets around pulsating subdwarf B stars

In 2007, a companion with planetary mass was found around the pulsating subdwarf B star V391 Pegasi with the timing method, indicating that a previously undiscovered population of substellar companions to apparently single subdwarf B stars might exist. Following this serendipitous discovery, the EXOTIME (http://www.na.astro.it/~silvotti/exotime/) monitoring program has been set up to follow the pulsations of a number of selected rapidly pulsating subdwarf B stars on time scales of several years with two immediate observational goals:

1. determine $\dot{P}$ of the pulsational periods P
2. search for signatures of substellar companions in O–C residuals due to periodic light travel time variations, which would be tracking the central star’s companion-induced wobble around the centre of mass

These sets of data should therefore, at the same time, on the one hand be useful to provide extra constraints for classical asteroseismological exercises from the $\dot{P}$ (comparison with “local” evolutionary models), and on the other hand allow one to investigate the preceding evolution of a target in terms of possible “binary” evolution by extending the otherwise unsuccessful search for companions to potentially very low masses. While timing pulsations may be an observationally expensive method to search for companions, it samples a different range of orbital parameters, inaccessible through orbital photometric effects or the radial velocity method: the latter favours massive close-in companions, whereas the timing method becomes increasingly more sensitive toward wider separations. In this paper we report on the status of the on-going observations and coherence analysis for two of the currently five targets, revealing very well-behaved pulsational characteristics in HS?0444+0458, while showing HS?0702+6043 to be more complex than previously thought.     

ISO-LWS Observations of the NGC7129 Star Forming Region

We present far-infrared observations of the surroundings of the Herbig Be star LkHα234 in NGC7129, obtained with the Long Wavelength Spectrometer on board of the Infrared Space Observatory. [CII]158μm, [OI]63μm and [OI]146μm lines are detected everywhere in the mapped region and their intensity ratios are consistent with the model predictions of a photodissociation region. The spatial distribution of the emission features indicates the presence of a peak which does not coincide with the position of LkHα234, but is more likely associated with another nearby Herbig star, namely BD+65°1637; the far-ultraviolet field intensity and the density derived from our observations are fully consistent with this hypothesis. This revised version was published online in July 2006 with corrections to the Cover Date.