Sensitivity analysis on the input parameters in probabilistic seismic hazard assessment     

A. Rebez  D. Slejko   《Soil Dynamics and Earthquake Engineering》2000,20(5-8):341-351

A project has been implemented in recent years for assessing seismic hazard in the Italian territory on probabilistic bases, to be used as scientific background for the revision of the current seismic zonation. A consolidated approach was considered for the purpose; seismic hazard was estimated in terms of peak ground acceleration and macroseismic intensity. As the computer code employed allows the user to make specific choices on some input data, some rather unorthodox decisions were taken regarding earthquake catalogue completeness, seismicity rates, boundaries of the seismogenic zones, definition of the maximum magnitude, attenuation relation, etc. The overwhelming amount of geological and seismological data for Italy (just consider, for example, that the earthquake catalogue collects events which occurred over the last ten centuries) permits the operator to make different choices, more or less cautiously. It is quite interesting, then, to evaluate the influence of the specific choices on the final hazard results as a comparison to traditional possibilities. The tests performed clearly indicate the critical choices and quantify their contribution. In particular, we consider thorough comprehension of the space geometry of the earthquake source boundaries and the adequacy of the attenuation relation in modelling the radiation pattern very important.  相似文献   

The role of lower continental crust and lithospheric mantle in the genesis of Plio–Pleistocene volcanic rocks from Sardinia (Italy)     

Michele Lustrino  Leone Melluso  Vincenzo Morra 《Earth and Planetary Science Letters》2000,180(3-4):259-270

The first comprehensive chemical and Sr–Nd–Pb isotopic data set of Plio–Pleistocene tholeiitic and alkaline volcanic rocks cropping out in Sardinia (Italy) is presented here. These rocks are alkali basalts, hawaiites, basanites, tholeiitic basalts and basaltic andesites, and were divided into two groups with distinct isotopic compositions. The vast majority of lavas have relatively high ⁸⁷Sr/⁸⁶Sr (0.7043–0.7051), low ¹⁴³Nd/¹⁴⁴Nd (0.5124–0.5126), and are characterised by the least radiogenic Pb isotopic composition so far recorded in Italian (and European) Neogene-to-Recent mafic volcanic rocks (²⁰⁶Pb/²⁰⁴Pb=17.55–18.01) (unradiogenic Pb volcanic rocks, UPV); these rocks crop out in central and northern Sardinia. Lavas of more limited areal extent have chemical and Sr–Nd–Pb isotopic ratios indicative of a markedly different source (⁸⁷Sr/⁸⁶Sr=0.7031–0.7040; ¹⁴³Nd/¹⁴⁴Nd=0.5127–0.5129; ²⁰⁶Pb/²⁰⁴Pb=18.8–19.4) (radiogenic Pb volcanic rocks, RPV), and crop out only in the southern part of the island. The isotopic ratios of these latter rocks match the values found in the roughly coeval anorogenic (i.e. not related to recent subduction events in space and time) mafic volcanic rocks of Italy (i.e. Mt. Etna, Hyblean Mts., Pantelleria, Linosa), and Cenozoic European volcanic rocks. The mafic rocks of the two Sardinian rock groups also show distinct trace element contents and ratios (e.g. Ba/Nb>14, Ce/Pb=8–25 and Nb/U=29–38 for the UPV; Ba/Nb<9, Ce/Pb=24–28 and Nb/U=46–54 for the RPV). The sources of the UPV could have been stabilised in the Precambrian after low amounts of lower crustal input (about 3%), or later, during the Hercynian Orogeny, after input of Precambrian lower crust in the source region, whereas the sources of the RPV could be related to processes that occurred in the late Palaeozoic–early Mesozoic, possibly via recycling of proto-Tethys oceanic lithosphere by subduction.  相似文献   

The Umbria-Marche (central Italy) earthquakes: relation between rupture directivity and sequence evolution for the Mw > 5 shocks     

N.A. Pino  S. Mazza 《Journal of Seismology》2000,4(4):451-461

We derive the relative moment rate function for the shocks with M_w > 5 in the 1997-98 central Italy seismic sequence, started with the M_w = 5.7, 09/26/97 00:33 event, by applying an empirical Green functionmethod. By using three conveniently placed broadband MedNet stations we obtain apparent source time functions indicating clear directivity effects for all of the analysed earthquakes, with rupture propagation generally directed outward from the epicentral area of the09/03/97 foreshock sequence. Taking a simple source model, forward modeling is utilized for determining fault parameters such as length, rupture propagation velocity and direction and, for the three major events,slip distribution. The effects of the break propagation directions onthe sequence evolution is discussed. A possible inconsistencyresults for the shallow 04/03/98 shock, which could be avoided if alink with the deep 03/26/98 event is assumed.Our analysis evidences the importance of a quick determination for the fault parameters in order to image the possible induction of fracturing on nearby structures.  相似文献   

Book Reviews     

《The Professional geographer》2000,52(3):567-590

Books reviewed: John Bale and Chris Philo Body Cultures: Essays on Sport, Space and Identity by Henning Eichberg. William A.V. Clark The California Cauldron: Immigration and the Fortunes of Local Communities. Tom Daniels When City and Country Collide: Managing Growth in the Metropolitan Fringe. David Delaney Race, Place, and the Law, 1836 – 1948. Allan K. Fitzsimmons Defending Illusions: Federal Protection of Ecosystems. Brian Graham Modern Europe: Place, Culture and Identity. William Least Heat‐Moon River Horse: The Logbook of a Boat Across America. George L. Henderson California and the Fictions of Capital. Martha Honey Ecotourism and Sustainable Development: Who Owns Paradise? Peter J. Hugill Global Communications Since 1844: Geopolitics and Technology. Thomas Klak Globalization and Neoliberalism: The Caribbean Context. David Knighton Fluvial Forms and Processes: A New Perspective. Gustavo Leclerc, Raul Villa, and Michael J. Dear Urban Latino Cultures: La Vida Latina en L.A. Daniel Miller, Peter Jackson, Nigel Thrift, Beverly Holbrook, and Michael Rowlands Shopping, Place and Identity. Martin Reuss Designing the Bayous: The Control of Water in the Atchafalaya Basin 1800–1995. Alan R. Townsend Making a Living in Europe: Human Geographies of Economic Change. Jennifer Wolch and Jody Emel Animal Geographies: Place, Politics and Identity in the Nature‐Culture Borderlands.  相似文献   

CN algorithm and long-lasting changes in reported magnitudes: the case of Italy     

A. Peresan  G. F. Panza  & G. Costa 《Geophysical Journal International》2000,141(2):425-437

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A model to simulate recharge processes of karst massifs   总被引：1，自引：0，他引：1       下载免费PDF全文

Francesco Fiorillo  Mauro Pagnozzi  Gerardo Ventafridda 《水文研究》2015,29(10):2301-2314

The recharge processes have been evaluated for two karst massifs of southern Italy, the Mt Terminio and Mt Cervialto, characterized by wide endorheic areas. The annual mean recharge has been estimated by Geographic Information System (GIS) tools, from regression of annual mean values of different ground‐elevated rain gauges and thermometers. The recharge has been distinguished for endorheic areas and the other areas of spring catchment, and the ratio between the output spring and input rainfall has been also estimated (recharge coefficient). The annual recharge has been used to calibrate a daily scale model, which allows to estimate the amount of effective rainfall, which is retained as soil moisture; the amount reaching the water table (recharge s.s.); and the amount of rainfall, which develops the runoff and leaves the catchment. All these amounts vary through the hydrological year, in function of soil moisture deficit and daily rainfall intensity. The model allows estimating the recharge conditions through the hydrological year, and it is a useful tool for water management. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Frontal compression along the Apennines thrust system: The Emilia 2012 example from seismicity to crustal structure     

《Journal of Geodynamics》2014

The evolution of the Apennines thrust-and-fold belt is related to heterogeneous process of subduction and continental delamination that generates extension within the mountain range and compression on the outer front of the Adria lithosphere. While normal faulting earthquakes diffusely occur along the mountain chain, the sparse and poor seismicity in the compressional front does not permit to resolve the ambiguity that still exists about which structure accommodates the few mm/yr of convergence observed by geodetic data. In this study, we illustrate the 2012 Emilia seismic sequence that is the most significant series of moderate-to-large earthquakes developed during the past decades on the compressional front of the Apennines. Accurately located aftershocks, along with P-wave and Vp/Vs tomographic models, clearly reveal the geometry of the thrust system, buried beneath the Quaternary sediments of the Po Valley. The seismic sequence ruptured two distinct adjacent thrust faults, whose different dip, steep or flat, accounts for the development of the arc-like shape of the compressional front. The first shock of May 20 (Mw 6.0) developed on the middle Ferrara thrust that has a southward dip of about 30°. The second shock of May 29 (Mw 5.8) ruptured the Mirandola thrust that we define as a steep dipping (50–60°) pre-existing (Permo-Triassic) basement normal fault inverted during compression. The overall geometry of the fault system is controlled by heterogeneity of the basement inherited from the older extension. We also observe that the rupture directivity during the two main-shocks and the aftershocks concentration correlate with low Poisson ratio volumes, probably indicating that portions of the fault have experienced intense micro-damage.  相似文献   

Seismic moment tensors and regional stress in the area of the December 2013–January 2014, Matese earthquake sequence (Italy)     

《Journal of Geodynamics》2014

The main goal of this study is to provide moment tensor solutions for small and moderate earthquakes of the Matese seismic sequence in southern Italy for the period of December 2013–January 2014. We estimate the focal mechanisms of 31 earthquakes with local magnitudes related to the Matese earthquake seismic sequence (December 2013–January 2014) in Southern-Central Italy which are recorded by the broadband stations of the Italian National Seismic Network and the Mediterranean Very Broadband Seismographic Network (MedNet) run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The solutions show that normal faulting is the prevailing style of seismic deformation in agreement with the local faults mapped out in the area. Comparisons with already published solutions and with seismological and geological information available allowed us to properly interpret the moment tensor solutions in the frame of the seismic sequence evolution and also to furnish additional information about less energetic seismic phases. Focal data were inverted to obtain the seismogenic stress in the study area. The results are compatible with the major tectonic domain of the area.  相似文献   

Environinformatics in ecological risk assessment of agroecosystems pollutant leaching     

Nazzareno Diodato  Michele Ceccarelli 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(4):292-300

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Tornadoes in Southern Apulia (Italy)     

F.?GianfredaEmail author  M.?M.?Miglietta  P.?Sansò 《Natural Hazards》2005,34(1):71-89

Numerous tornadoes have traversed southern Apulia in the course of the last five centuries, causing severe damage and a significant loss of life. Historical chronicles and newspaper articles allowed more than 30 tornadic events to be identified; in particular, 26 of these have occurred during the last two centuries. In all, 24 small towns and villages of southern Apulia suffered on at least one occasion the disastrous effects of being hit by a tornado.Collated data reveals that tornadoes generally form from May to December, with the most powerful events taking place in the month of September, followed by October and November. Tornadoes generally cluster in the southernmost area of the region and typically follow a path leading from the south-west to the north-east. Path length were observed to vary from 8 to 73km, and widths ranging from 60 to 850m.The metereological analysis carried out for the events occurred after 1950, even if based on a limited data set, reveals a few typical meteorological scenarios associated with the development of tornadoes over Salento.In southern Apulia tornadoes can be classified from levels A2 to A4 in accordance with the Damage Area Scale.  相似文献