Seismic response of L��Aquila downtown from comparison between 2D synthetics spectral ratios of SH, P-SV and Rayleigh waves and observations of the 2009 earthquake sequence

This is the first part of a study on the seismic response of the L’Aquila city using 2D simulation and experimental data. We have studied two velocity-depth models with the aim of outlining the behavior of a velocity reversal in the top layer, which is associated with the stiff Brecce de L’Aquila unit (BrA). In this setting, the SMTH model is topped by a layer with about 2:1 impedance contrast with the underlying layer while the NORV model has no velocity reversal. We have simulated the propagation of SH and P-SV wavefields in the range 0–10 Hz for incidence 0°–90°. Earthquake spectral ratios of the horizontal and vertical components at six sites in L’Aquila downtown are compared to corresponding synthetics spectral ratios. The vertical component of P-SV synthetics enables us to investigate a remarkable amplification effect seen in the vertical component of the recorded strong motion. Sites AQ04 and AQ05 are best matched by synthetics from the NORV model while FAQ5 and AQ06 have a better match with synthetics spectral ratios from the SMTH model. All simulations show this behavior systematically, with horizontal and near-horizontal incident waves predicting the overall pattern of matches more clearly than vertical and near-vertical incidence. The model inferences are in agreement with new geological data reporting lateral passages in the top layer from the stiff BrA to softer sediments. Matches are good in terms of frequency of the first amplification peak and of spectral amplitude: the horizontal components have spectral ratio peaks predominantly at 0.5 Hz in the simulations and at 0.7 Hz in the data, both with amplitudes of 4, while the vertical component spectral ratios reach values of 6 at frequencies of about 1 Hz in both data and simulations. The vertical component spectral ratios are very well matched using Rayleigh waves with incidence at 90°. The NORV model without the velocity reversal predicts spectral ratio peaks for the horizontal components at frequencies up to 6 Hz. The reversal of velocity acts as a low-pass frequency filter on the horizontal components reducing the amplification effect of the sediment filled valley.     

For a Europe of flexible regions and not of region-states divided by ethnicity

Discussion of the future of Europe continues to be a marginal political issue, partly because of the resistance of states, on both the practical (bureaucratic) and conceptual levels, created by the government leaders and heads of state. In turn, the nation-states are challenged from within by independent and separatist movements that have laid bare the fundamental hypocrisy of rhetorical discussions of the principle regarding the self-determination of peoples; interfering with states (and their borders) has proven to be a taboo for Europe. The growing flexibility of the globalised economy should be paralleled by a growing flexibility in the conception of the division and political organisation of territory, but this is not the case. Further inflexibility stems from the socio-economic inequity that we accept in our daily lives as normal, in particular as regards inequality in the use and division of territory. Equality, or better egaliberté (equality and liberty), is a sufficiently dynamic and flexible concept to be taken as a point of reference in envisaging the society, Europe, and world of tomorrow. It is only through the concept of egaliberté that we can imagine a Europe based on relations between regions that are conceived and organised on multiple scales and not as region-nations conceived on the basis of ethnicity or in the name of supposed cultural homogeneity.     

The Calabrian Stage redefined

The name Calabrian was introduced in the geological literature by the French stratigrapher Maurice Gignoux in 1910, and later described in his important monograph （633 pages） ＂Les formations marines pliocknes et quaternaires de l＇ltalie du sud et de la Sicile ＂published in 1913. Detailed data were provided on several sections （Santa Maria di Catanzaro, Caraffa, Monasterace, Palermo） and on their fossil content. The Calabrian Stage has commonly been used for over fifty years as the oldest subdivision of the Qua- ternary, notably in the time scales of Berggren ＆ van Cou- vering （1974） and Haq ＆ Eysinga （1987）. However, after the GSSP for the Pliocene/Pleistocene boundary （P/P） was approved by INQUA in 1982 and ratified by lUGS in 1984 at the Vrica section of Calabria, there was a decline in the usage of the stage name, and an increasing tendency by many Quaternary workers to question the boundary stratotype. This was because there was increasing evidence that it did not correspond to the beginning of the ＂ice age＂. In doing so, they were not complying with the recommendations presented at the 18th International Geological Congress （IGC） in London, 1948 （Oakley, 1950）.     

High-pressure behaviour along the jadeite NaAlSi2O6–aegirine NaFeSi2O6 solid solution up to 10 GPa

The volume variation as a function of pressure along the jadeite–aegirine solid solution was determined at room temperature up to pressures between 6.5 and 9.7 GPa by single-crystal X-ray diffraction. The unit-cell volumes collected at room pressure for the different compositions indicate a slight deviation from linearity along the join. The pressure–volume data have been fitted using a third-order Birch-Murnaghan equation of state (BM3-EoS). The bulk modulus, K _T0, varies from 134.0(7) GPa for pure jadeite to 116.1(5) GPa for pure aegirine. Its evolution with composition along the join is not linear and can be described by the following second order polynomial:

Seismic fragility of reinforced concrete girder bridges using Bayesian belief network

Infrastructure owners and operators, or governmental agencies, need rapid screening tools to prioritize detailed risk assessment and retrofit resources allocation. This paper provides one such tool, for use by highway administrations, based on Bayesian belief network (BBN) and aimed at replacing so‐called generic or typological seismic fragility functions for reinforced concrete girder bridges. Resources for detailed assessments should be allocated to bridges with highest consequence of damage, for which site hazard, bridge fragility, and traffic data are needed. The proposed BBN based model is used to quantify seismic fragility of bridges based on data that can be obtained by visual inspection and engineering drawings. Results show that the predicted fragilities are of sufficient accuracy for establishing relative ranking and prioritizing. While the actual data and seismic hazard employed to train the network (establishing conditional probability tables) refer to the Italian bridge stock, the network structure and engineering judgment can easily be adopted for bridges in different geographical locations. Copyright © 2015 John Wiley & Sons, Ltd.     

An ESA NEOCC Effort to Eliminate High Palermo Scale Virtual Impactors

In this work we summarize the initial results of a targeted effort of the ESA NEO Coordination Centre to obtain additional observational data in order to eliminate or reduce the impact probability estimate of a subset of the known near-Earth objects representing the highest fraction of the total known impact risk, as measured by the Palermo Scale.     

δ 11B as tracer of slab dehydration and mantle evolution in Western Anatolia Cenozoic Magmatism

Boron isotope data are presented for Cenozoic Western Anatolia rocks, which define two main associations: (i) calc-alkaline, shoshonitic and ultra-potassic rocks (Early to Middle Miocene); and (ii) Late Miocene–Quaternary intraplate alkali basalts. Boron data, together with Sr–Nd isotope and other trace elements, are consistent with a progressive dehydration of the slab, producing fluid phases gradually depleted in B (and ¹¹B). These fluids were added to the supraslab mantle, triggering a partial melting that gave rise to orogenic magmatism. The stretching and tearing of the slab caused by the faster convergence of Greece over Africa with respect to Anatolia facilitated an interaction of the upwelling subslab asthenosphere with residual slab-fluids during the Late Miocene followed by production of typical intraplate magmas during the Pleistocene–Holocene, whose relatively high δ¹¹B (approximately −2‰) is considered representative of the local asthenosphere not affected by subduction contamination.     

Estimation procedures for exchangeable Marshall copulas with hydrological application

Complex phenomena in environmental sciences can be conveniently represented by several inter-dependent random variables. In order to describe such situations, copula-based models have been studied during the last year. In this paper, we consider a novel family of bivariate copulas, called exchangeable Marshall copulas. Such copulas describe both positive and (upper) tail association between random variables. Specifically, inference procedures for the family of exchangeable Marshall copulas are introduced, based on the estimation of their (univariate) generator. Moreover, the performance of the proposed methodologies is shown in a simulation study. Finally, an illustration describes how the proposed procedures can be useful in a hydrological application.