Space–time correlation of earthquakes     

Patrizia Tosi  Valerio De Rubeis  Vittorio Loreto  Luciano Pietronero 《Geophysical Journal International》2008,173(3):932-941

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Sardinia Coastal Uplift and Volcanism     

Patrizia Mariani  Carla Braitenberg  Fabrizio Antonioli 《Pure and Applied Geophysics》2009,166(8-9):1369-1402

The low variability of MIS 5.5 sea level (M.I.S = Marine Isotopic Stage) with respect to the present day sea level, allows the Sardinian coast to be used as an eustatic reference for the entire Mediterranean region. This level is generally at 7 ± 2 m above current sea level along the Sardinian coast. One sector along the Orosei Gulf (eastern Sardinia) includes a characteristic and well conserved tidal notch that changes in elevation from 7.6 to 11.5 m over only 30 km, tilting upwards towards the north. Generally, height deviations of such a tidal notch would be due to tectonic or volcanic activity. The Sardinia coast however, is considered to have too little tectonic activity, and also too small post-glacial rebound in order to explain the anomaly. The remaining possibility is Neogene-Quaternary continental and/or submarine volcanic activity, which we investigate as a possible cause for the observed anomalies. In this paper, our goal is to explain the anomaly by modelling recent volcanic loading or updoming related to magmatic intrusion emplacement. We review the literature on the recent volcanic deposits, both on-shore and off-shore, and investigate to what extent volcanic loads can influence the coastline from a theoretical standpoint, using the isostatic flexure model and a range of loads. We find that the observed notch height anomaly cannot be explained by volcanic loading, but must be produced by an upward welling due to the emplacement of volcanic material, as produced for instance by a laccolith or batholith. The upward movement could be related to the submarine volcano only recently detected, or to a source located on the eastern Sardinia coast near Orosei.  相似文献   

Organochlorine compounds in tissues of swordfish (Xiphias gladius) from Mediterranean Sea and Azores islands     

Stefanelli P  Ausili A  Di Muccio A  Fossi C  Di Muccio S  Rossi S  Colasanti A 《Marine pollution bulletin》2004,49(11-12):938-950

Polychlorobiphenyls (PCB) and organochlorine (OC) pesticides are endocrine-disrupting chemicals (EDCs). The Italian Ministry of Environment has undertaken a program (1999-2001) to measure levels of contaminants in top marine predators and to develop sensitive biomarkers for the evaluation of toxicological risk in these species. In 1999, 15 swordfishes (Xiphias gladius) taken from the Mediterranean Sea along the Sicilian coast (Strait of Messina, Italy) and in the Atlantic Ocean along the Azores Islands, and analysed for 34 congeners of PCBs and 27 organochlorine (OC) pesticides in gonad, muscle, liver and blubber tissues. In the tissues of Mediterranean swordfishes the sum of the determined PCBs congeners ranged from 4.61 to 4651.17 ng g(-1) on fresh tissue basis. Among organochlorine pesticides DDE, DDT and DDD (TDE) predominated with an overall range of 2.37-4734.56 ng(-1) w.w. In particular p,p'-DDE had concentrations appearing up to 3900 ng(-1), with the highest values found in fatty tissues, such as blubber. In the liver of Azores Island swordfishes lower levels of summation PCBs (8.43-294.17 ng/g w.w.) and summation DDTs (<0.01-217.44 ng/g w.w.) were determined.  相似文献   

An attempt to evaluate seismic hazard in Central-Southern Italy     

A. Basili  P. Favali  G. Scalera  G. Smriglio 《Natural Hazards》1984,3(1):31-47

A method for the evaluation of seismic hazard in a given zone, taking into account both the spreading of macroseismic effects and seismic catalogue information, is applied. A data-bank of some 500 digitized isoseisms of earthquakes having occurred in Italy between 1542 and 1986 is used. The isoseismical maps are digitized considering for each degree of intensity the length of 24 spreading rays starting from the macroseismic epicenter or barycentre of the megaseismic area. These rays are separated from each other by the same angle, i.e. every isoseism is divided into 24 equal circular sectors. The year 1542 is taken as the beginning of the time span, since this is when the first seismic event occurred for which reliable isoseismal maps are available. The epicentral intensities considered lie between theVI andXI degrees of the Mercalli-Cancani-Sieberg scale (MCS). This digitized data-bank is analyzed to achieve, for each homogeneous seismogenetic zone that has been recognized, the mean azimuthal spreadings of effects for each degree of intensity as a function of the epicentral intensity. Once a mean propagation model is obtained for each zone, this is applied to seismic events of the same zone, the isoseismal maps of which are not available. A geographic grid is defined to cover the analyzed area, and for each cell of this grid it is then possible to count the number of felt events and their degree. These effects have been evaluated either on the basis of the isoseismal maps (when available) or on the basis of the mean propagations of the zone in which the single event occurred. Moreover, an index summarizing the seismic information was computed for each cell of the previous grid. All the events producing effects and their provenance are stored on files, allowing the main seismogenic zones influencing this cell to be identified. This methodology has been applied to central and southern Italy in an area between the latitudes 40.6 and 43.3 N. In particular, attention is focussed on the sample areas of Rome (given the historical and political importance of the city) and of the Sannio-Matese and Irpinia zone (in which some of the strongest earthquakes of the Apennine chain have occurred). Finally, in order to evaluate the maximum expected magnitude, extreme value statistics (Gumbel III-type) are applied to the Colli Albani area, which represents the seismogenic zone nearest to Rome. For the Sannio-Matese and Irpinia area, considering the more dangerous zone as a unicum, theWeibull distribution has been hypothesized to determine the mean return time for events with an intensity greater than or equal to IX.  相似文献   

An ordered probit model for seismic intensity data     

Michela?CamelettiEmail author  Valerio?De Rubeis  Clarissa?Ferrari  Paola?Sbarra  Patrizia?Tosi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(7):1593-1602

Seismic intensity, measured through the Mercalli–Cancani–Sieberg (MCS) scale, provides an assessment of ground shaking level deduced from building damages, any natural environment changes and from any observed effects or feelings. Generally, moving away from the earthquake epicentre, the effects are lower but intensities may vary in space, as there could be areas that amplify or reduce the shaking depending on the earthquake source geometry, geological features and local factors. Currently, the Istituto Nazionale di Geofisica e Vulcanologia analyzes, for each seismic event, intensity data collected through the online macroseismic questionnaire available at the web-page www.haisentitoilterremoto.it. Questionnaire responses are aggregated at the municipality level and analyzed to obtain an intensity defined on an ordinal categorical scale. The main aim of this work is to model macroseismic attenuation and obtain an intensity prediction equation which describes the decay of macroseismic intensity as a function of the magnitude and distance from the hypocentre. To do this we employ an ordered probit model, assuming that the intensity response variable is related through the link probit function to some predictors. Differently from what it is commonly done in the macroseismic literature, this approach takes properly into account the qualitative and ordinal nature of the macroseismic intensity as defined on the MCS scale. Using Markov chain Monte Carlo methods, we estimate the posterior probability of the intensity at each site. Moreover, by comparing observed and estimated intensities we are able to detect anomalous areas in terms of residuals. This kind of information can be useful for a better assessment of seismic risk and for promoting effective policies to reduce major damages.  相似文献