A WebGis tool for seismic hazard scenarios and risk analysis     

Vera Pessina  Fabrizio Meroni 《Soil Dynamics and Earthquake Engineering》2009

The WebGis development represents a natural answer to the growing requests for dissemination and use of geographical information data. WebGis originates from a combination of web technology and the Geographical Information System, which is a recognised technology that is mainly composed of data handling tools for storage, recovery, management and analysis of spatial data. Here, we illustrate two examples of seismic hazard and risk analysis through the WebGis system in terms of architecture and content. The first presents ground shaking scenarios associated with the repetition of the earthquake that struck the Lake of Garda area (northern Italy) in 2004. The second shows data and results of a more extensive analysis of seismic risk in the western part of the Liguria region (north-western Italy) for residential buildings, strategic structures and historic architecture. The adoption of a freeware application (ALOV Map) assures easy exportability of the WebGis structures for projects dealing with natural hazard evaluation.  相似文献   

Are fiddler crabs potentially useful ecosystem engineers in mangrove wastewater wetlands?     

Gil Penha-Lopes  Fabrizio Bartolini  Samwel Limbu  Stefano Cannicci  Erik Kristensen  Jos Paula 《Marine pollution bulletin》2009,58(11):1694-1703

The effect of different organic-rich sewage concentration (0%, 20% and 60% diluted in seawater) and absence or presence of mangrove trees on the survival, bioturbation activities and burrow morphology of fiddler crabs species was assessed. After 6 months, males of both species always showed higher survival (80%) when compared to females (20%). Crabs inhabiting pristine conditions achieved higher survival (67–87%) than those living in sewage-exposed mesocosms (40–71%). At 60% sewage loading, fiddler crabs processed less sediment (34–46%) during feeding and excavated slightly more sediment (45–80%) than at pristine conditions. While percent volume of the burrow chambers increased (13–66%) at contaminated mesocosms for both vegetation conditions, burrows were shallower (33%) in bare cells loaded with sewage. The results show that fiddler crabs presented moderate mortality levels in these artificial mangrove wetlands, but mainly in sewage impacted cells. However, they still function as ecosystem engineers through bioturbation activities and burrow construction.  相似文献   

F-phlogopites in the Alban Hills Volcanic District (Central Italy): indications regarding the role of volatiles in magmatic crystallisation     

M. Gaeta  G. Fabrizio  G. Cavarretta 《Journal of Volcanology and Geothermal Research》2000,99(1-4)

A systematic analysis of micas contained in effusive, pyroclastic and hypabyssal rocks of the Alban Hills Volcanic District (AHVD) (Central Italy) was made in order to characterise minerals of pyroclastic units for tephrostratigraphy and to obtain as much information as possible on the activity of volatiles in this magmatic system. The phlogopite shows a large range of F contents (between 0.50 and 7.50 wt%) that make it possible to discriminate different AHVD lithologies; in particular, micas of lava groundmass are characterised by extremely high F (up to 7.50 wt%) and Ba (up to 9.70 wt%) contents, seldom or never found in other magmatic ultrapotassic rocks. Moreover, the micas of pyroclastics, ultramafic cumulates and holocrystalline inclusions made up of leucite, clinopyroxene and phlogopite (hereafter italites) show Mg/(Mg+Fe) values between 0.65 and 0.90 that are not correlated with F contents. The variations in F contents observed in the AHVD micas do not appear to be due to a “temperature” effect or pressure changes, but they may be due to variations in the H₂O and CO₂ activities in the magma chamber. They make it possible to differentiate three crystallisation environments in the AHVD magmatic system. The first one had elevated CO₂ activity and formed the italites near the carbonate contact; these rocks represent, at least those enriched in clinopyroxene without skarn-minerals, the hypabyssal crystallisation of the AHVD magmas at the periphery of magma chamber. The second one, characterised by a higher water activity, is represented by the micas of the ultramafic cumulates and pyroclastic scorias, and is located in the inner part of magma chamber. The third environment, the groundmass of the lavas, it is not related with the previous ones and is characterised by the absence of water and by a high F activity. In general, our results suggest that the compositional variations observed in the micas (Al, Si, Ti, Ba) reflect different H₂O activities (inversely correlated with F activity) in the magma chamber.  相似文献   

Preliminary ranking of alternative scalar and vector intensity measures of ground shaking   总被引：3，自引：3，他引：0  

Hossein Ebrahimian  Fatemeh Jalayer  Andrea Lucchini  Fabrizio Mollaioli  Gaetano Manfredi 《Bulletin of Earthquake Engineering》2015,13(10):2805-2840

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Median floor acceleration spectra of linear structures with uncertain properties          下载免费PDF全文

Andrea Lucchini  Paolo Franchin  Fabrizio Mollaioli 《地震工程与结构动力学》2017,46(12):2055-2060

Response parameters used to estimate nonstructural damage differ depending on whether deformation‐sensitive or acceleration‐sensitive components are considered. In the latter case, seismic demand is usually represented through floor spectra, that is response spectra in terms of pseudo‐acceleration, which are calculated at the floor levels of the structure where the nonstructural components are attached to. Objective of this paper is to present a new spectrum‐to‐spectrum method for calculating floor acceleration spectra, which is able to explicitly account for epistemic uncertainties in the modal properties of the supporting structure. By using this method, effects on the spectra of possible variations from nominal values of the periods of vibration of the structure can be estimated. The method derives from the extension of closed‐form equations recently proposed by the authors to predict uniform hazard floor acceleration spectra. These equations are built to rigorously account for the input ground motion uncertainty, that is the record‐to‐record variability of the nonstructural response. In order to evaluate the proposed method, comparisons with exact spectra obtained from a standard probabilistic seismic demand analysis, as well as spectra calculated using the Eurocode 8 equation, are finally shown. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Monitoring of structural systems by using frequency data     

Danilo Capecchi  Fabrizio Vestroni 《地震工程与结构动力学》1999,28(5):447-461

The present work evaluates the possibility of using dynamic data to assess structural integrity. It addresses the problem of understanding when it is sufficient to measure and use only natural frequencies, thus avoiding the need to measure modal shapes. The classic problem of detecting damage in beams, or beam assemblies, due to concentrated cracks, or damage spread over a structural member is dealt with. Damage is represented as a decrease in stiffness and linear behaviour before and after the event assumed to have caused damage is considered. Damage is restricted to a few unknown sections or elements, so that only the modification of few parameters of the system need to be determined. This study thus rejects assumptions unrelated to the physical aspects of the problem, in contrast to many papers on the subject. The amount of data to locate and quantify damage correctly is discussed; general considerations lead to the conclusion that a unique and reliable estimate of the damage can be obtained using only few additional frequency data with respect to the number of damaged zones. Continuous and discrete (finite element) models are examined. Finally the paper considers the applications to both analytical and experimental data of the procedure developed, which takes account of the peculiar characteristics of damage detection problem. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Formulation of elastic earthquake input energy spectra     

Luis D. Decanini  Fabrizio Mollaioli 《地震工程与结构动力学》1998,27(12):1503-1522

The object of this paper is to introduce a procedure for the determination of elastic design earthquake input energy spectra taking into account the influence of magnitude, soil type and distance from the surface projection of the fault. Firstly, an accurate selection of a large set of representative records has been realized. Secondly, the construction of the design input energy spectra has required determining the spectral shapes and a normalization factor which measures seismic hazard in terms of energy. This factor, denoted as the seismic hazard energy factor, has been defined as the area under the earthquake input energy spectrum in the period interval between 0·05 and 4·0 s. Finally, due to the importance of the source-to-site distance in the evaluation of the input energy, an investigation into the attenuation of the seismic hazard energy factor has been carried out. © 1998 John Wiley & Sons, Ltd.  相似文献   

Northwest Africa 6232: Visible–near infrared reflectance spectra variability of an olivine diogenite     

Cristian Carli  Giovanni Pratesi  Vanni Moggi-Cecchi  Francesca Zambon  Fabrizio Capaccioni  Simone Santoro 《Meteoritics & planetary science》2018,53(10):2228-2242

Visible and near-infrared (VNIR) reflectance is an important spectroscopic technique to identify minerals, and their associations, on planetary body surfaces. Howardites, eucrites, and diogenites (HED) are a class of igneous-like meteorites whose genetic connection with asteroid 4 Vesta has since long been inferred and recently confirmed by Dawn mission results. Pyroxene and olivine are the two major mafic minerals present in HED which can be identified with VNIR reflectance measurements. Thus, studying the compositional variability of those phases and their mixtures by means of laboratory spectroscopic measurements on different diogenitic or eucritic samples is one of the prime methods to better understand the evolution of 4 Vesta's crust. Here, we report the VNIR reflectance spectral analysis of a harzburgitic olivine diogenite, Northwest Africa 6232 (probably paired with Northwest Africa 5480), containing variable amounts of olivine as small grains or aggregates. We found that the olivine diogenite spectral parameters (e.g., band position) of powdered samples and polished slabs are in agreement. Moreover, the olivine diogenite band position shifts from synthetic orthopyroxene in accordance with the presence of olivine and chromite. In particular, the presence of a large olivine clast permits us to determine a linear variation of the band position from synthetic orthopyroxene and olivine, but underestimates the presence of olivine in the olivine diogenite spot.  相似文献   

Effects of urban wastewater on crab and mollusc assemblages in equatorial and subtropical mangroves of East Africa     

Stefano Cannicci  Fabrizio Bartolini  Farid Dahdouh-Guebas  Sara Fratini  Carlos Litulo  Adriano Macia  Elisha J. Mrabu  Gil Penha-Lopes  Jos Paula 《Estuarine, Coastal and Shelf Science》2009,84(3):305

Mangrove forests are known to accomplish crucial ecosystem functions and services. They are nursery areas for fish, prawns and crabs, which provide coastal communities with a variety of food, timber and chemicals, and protect coasts from catastrophic events, such as tsunamis. Recently, a novel ecological service has been proposed for mangrove systems, namely natural wastewater treatment wetlands. This hypothesis was based on experimental data collected mainly in Chinese mangrove systems, which proved that mangrove soils were efficient in absorbing nutrients. Moreover, sewage loading seemed harmless to both plants and benthic communities in these systems. However, before promoting the use of natural mangroves as pollution buffers, or constructed mangrove wetlands as sewage treatment facilities, more data are needed on their overall tolerance to organic loading. Differences in macrobenthos patterns were thus investigated between peri-urban mangroves and sites not affected by sewage disposal in East Africa. We assessed differences in epifaunal assemblages, comprising crabs and molluscs, employing multivariate ACI unbalanced analyses to compare peri-urban mangrove swamps with those characteristic of non-urban mangroves with similar ecological traits. The sampling design was spatially nested, replicates being assessed at equatorial (southern Kenya) and subtropical (southern Mozambique) sites. The results manifested a consistent increase in crab biomass at the peri-urban sites in both Kenya and Mozambique. Moreover, the peri-urban systems were richer than the non-urban mangroves, both in terms of fiddler crabs (Uca spp.) which feed on benthic microalgae and bacteria, and sesarmids, such as Perisesarma guttatum and Neosarmatium meinerti, which feed on both substratum and leaf litter. The abundance of gastropods, in contrast, decreased significantly, especially in Kenya, mainly due to the disappearance of the mud whelk Terebralia palustris. The results thus indicate that, in East African mangrove systems, domestic wastewater has detectable effects on crabs and molluscs, suggesting their usefulness as bioindicators of its effects in mangroves. Transformed benthic patterns at the peri-urban sites indicated the need for further study of the actual potential of natural mangrove forests to absorb pollution in sewage treatment.  相似文献   

Changes in biomass structure and trophic status of the plankton communities in a highly dynamic ecosystem (Gulf of Venice,Northern Adriatic Sea)     

Alessandra Pugnetti  Anna Maria Bazzoni  Alfred Beran  Fabrizio Bernardi Aubry  Elisa Camatti  Mauro Celussi  Joan Coppola  Erica Crevatin  Paola Del Negro  Alessandro Paoli 《Marine Ecology》2008,29(3):367-374

The changes in the plankton biomass structure in relation to nutrient inputs were studied in the Gulf of Venice (Northern Adriatic Sea), an area characterized by a very marked trophic state variability. The investigation was carried out at two stations, in March, May and July 2005 and 2006, considering the whole water column. The size structure (from picoplankton to mesozooplankton) of both autotrophs and heterotrophs was analysed. Signals of diluted waters and nutrient inputs were more marked in 2005 than in 2006. In 2005, the total plankton biomass was almost double (87 ± 37 μg·C·l^?1) that in 2006 (44 ± 26 μg·C·l^?1). The variations were determined mainly by phytoplankton, with a 70% decrease, and a shift from a community dominated by microphytoplankton (49 ± 12%) in 2005 to one dominated by bacteria (43 ± 11%) in 2006 was observed. The relationship between the heterotrophic (H) and autotrophic (A) biomass indicated a rapid decline of the H/A ratio with increasing phytoplankton biomass. This study, although temporally limited, is consistent with the results reported for other marine environments and it seems to confirm the importance of nutrient inputs in structuring the biomass of plankton community.  相似文献