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In this paper earthquake damage scenarios for residential buildings (about 4200 units) in Potenza (Southern Italy) have been estimated adopting a novel probabilistic approach that involves complex source models, site effects, building vulnerability assessment and damage estimation through Damage Probability Matrices. Several causative faults of single seismic events, with magnitude up to 7, are known to be close to the town. A seismic hazard approach based on finite faults ground motion simulation techniques has been used to identify the sources producing the maximum expected ground motion at Potenza and to generate a set of ground motion time histories to be adopted for building damage scenarios. Additionally, site effects, evaluated in a previous work through amplification factors of Housner intensity, have been combined with the bedrock values provided by hazard assessment. Furthermore, a new relationship between Housner and EMS-98 macroseismic intensity has been developed. This relationship has been used to convert the probability mass functions of Housner intensity obtained from synthetic seismograms amplified by the site effects coefficients into probability mass function of EMS-98 intensity. Finally, the Damage Probability Matrices have been applied to estimate the damage levels of the residential buildings located in the urban area of Potenza. The proposed methodology returns the full probabilistic distribution of expected damage, thus avoiding average damage index or uncertainties expressed in term of dispersion indexes.  相似文献   
184.
A tornado with severe intensity hit the municipalities of Pianiga, Dolo and Mira close to Venice, northeast Italy, causing damages on a wide number of residential and industrial buildings and destroying some historical villas. In this study, the authors show the results of the damage assessment survey performed in the first days after the occurrence of the extreme event. Limited literature deals with damage assessment of European building types due to wind actions, and the available one does not consider building vulnerability as key factor in the structural response of existing structures subject to tornado hazard. In this paper, structural damages surveyed in reinforced concrete frame structures and masonry buildings, representative of common Italian building types, are critically discussed. Additionally, this work provides a database of past tornado events in northeast Italy, evidencing how the analyzed area has been found to be quite prone to tornado hazard.  相似文献   
185.
This paper presents the application of the multi-stage first-order centered scheme GMUSTA to solve a two-phase flow model with four equations for simulating dam-break floods without and with sediment transport.Computation of generalized Riemann invariants can be particularly complex and costly in simulating dam-break floods with sediment transport.GMUSTA numerical scheme,which does not require complete knowledge of the eigenstructure of the hyperbolic mathematical model,offers a suitable and attractive option.The quality of the dam-break flood simulations with GMUSTA scheme is verified by comparing the results against laboratory tests and some experimental data available in the literature,on fixed and mobile bed conditions,with different bed materials and flush or stepped bottoms.The numerical results reproduce quite well the experimental evidence,proving that the model is capable of predicting the temporal evolution of the free-surface and the bed.The GMUSTA scheme,which is not only simple to implement but also both accurate and computationally efficient,is proposed as an appropriate tool for integrating non-equilibrium sediment-transport models.  相似文献   
186.
The town of Orvieto, located on the Rock of the same name, is an example of “vulnerable town”; problems of slope instability connected with the lithological and morphological characteristics of the Rock have been thoroughly examined and discussed during previous research studies. Hydrogeochemical data about groundwater recharging the springs present in the area were never taken into account. Pollution of the springs is well known but still occurs for unclear reasons. The aim of this work is therefore to present the results of a hydrogeological and geochemical investigation of all the springs along the slopes of Orvieto hill and at the foot of the tuffaceous Rock, to characterize the groundwater flow paths and to suggest a possible source of contamination. The research study was carried out during three hydrogeochemical surveys in the years 1998–1999, 2003–2004, and 2007–2008.  相似文献   
187.
The Planalto da Serra igneous rocks form plugs, necks and dykes of carbonate-rich ultramafic lamprophyres (aillikites and glimmerites with kamafugitic affinity) and carbonatites (alvikites and beforsites). Phlogopite and/or tetraphlogopite, diopside and melanitic garnet are restricted to aillikitic rock-types, whereas pyroclore occurs only in carbonatites. Aillikites and carbonatites are altered to hydrotermalites, having chlorite and serpentine as dominant minerals. Planalto da Serra igneous rock association has kamafugitic affinity (i.e. effusive, ultrapotassic. High LREE/HREE fractionation, incompatible elements data and Sr-Nd isotopes, suggest that the K-ultramafic alkaline and carbonatite rocks originated from a variably metasomatized mantle source enriched in radiogenic Sr. Crustal contamination is negligible or absent. Age values of 600 Ma rule out the geochronological relationship between the investigated intrusions and the Mesozoic alkaline bodies from the Azimuth 125° lineament. The TDM model ages allow to conclude that Planalto da Serra magma is derived from the partial melting of a mantle source metasomatised by K-rich carbonatated melt during the Early to Late Neoproterozoic. On the basis of alkaline magmatism repetitions at 600 Ma and 90–80 Ma we question the subsistence of a stationary mantle plume for so long time.  相似文献   
188.
Most impacts occur at an angle with respect to the horizontal plane. This is primarily reflected in the ejecta distribution, but at very low angle structural asymmetries such as elongation of the crater and nonradial development of the central peak become apparent. Unfortunately, impact craters with pristine ejecta layers are rare on Earth and also in areas with strong past or ongoing surface erosion on other planetary bodies, and the structural analysis of central peaks requires good exposures or even on‐site access to outcrop. However, target properties are known to greatly influence the shape of the crater, especially the relatively common target configuration of a weaker layer covering a more rigid basement. One such effect is the formation of concentric craters, i.e., a nested, deeper, inner crater surrounded by a shallow, outer crater. Here, we show that with decreasing impact angle there is a downrange shift of the outer crater with respect to the nested crater. We use a combination of (1) field observation and published 3‐D numerical simulation of one of the best examples of a terrestrial, concentric impact crater formed in a layered target with preserved ejecta layer: the Lockne crater, Sweden; (2) remote sensing data for three pristine, concentric impact craters on Mars with preserved ejecta layers further constraining the direction of impact; as well as (3) laboratory impact experiments, to develop the offset in crater concentricity into a complementary method to determine the direction of impact for layered‐target craters with poorly preserved ejecta layers.  相似文献   
189.
Featuring 3 000-km-long large and hot orogen, the Mantiqueira Province provides a rare opportunity to study the process of gravitational collapse at mid to deep crustal levels. Distinct but contemporary (~500 Ma) post-collisional intrusions show structures and anisotropy of magnetic susceptibility (AMS) fabrics related to their emplacements, recording different flow patterns. In southern deep-seated intrusions, ellipsoidal-shaped roots with gabbroic-to-hybrid cores surrounded by granitic rocks show concentric patterns of AMS fabrics that cut across the NE-trending regional foliation. In contrast, northern intrusions, exposed as the upper sections of batholith-size bodies of coarse-grained granite emplaced at the shallow to mid-crust, show general NS-trending magnetic fabrics roughly parallel to strike of the orogen and the regional foliation of host rocks. These contrasting magnetic patterns from shallow to deeper crust suggest vertical magma migration from the overthickened orogenic core to be emplaced across its thinner stretched flanks during the gravitational collapse of the orogenic edifice.  相似文献   
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