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161.
Authors Index
Index to volume 4 相似文献162.
G. De Luca R. Scarpa L. Filippi A. Gorini S. Marcucci P. Marsan G. Milana E. Zambonelli 《Journal of Seismology》2000,4(1):1-21
A three-component digital seismic network has been installed along central Apennines since the end of 1991. Two seismic sequences having main shocks of magnitudes 3.9 and 3.7 were recorded in August 1992 and June 1994, respectively. A detailed analysis of these sequences, including multiplet relocation, fault-plane solutions and source parameter estimation, is performed in the present paper. A correlation analysis allowed us to recognize a number of correlated events in the two sequences which were used for relative locations using a master event technique. This analysis allowed to obtain a better alignment of epicentral data along two almost orthogonal directions, following an Apenninic and an anti-Apenninic trend. For the two sequences, fault-plane solutions were evaluated by using a first arrival technique, resulting in mechanisms with predominant normal faulting for the 1992 and 1994 swarms. S-wave polarization analysis allowed to check the stability of the previous solutions and to reduce their range of uncertainty. The same technique was also applied to derive the composite fault-plane solutions from the aftershocks, resulting in solutions which are in good agreement with those derived from the main shocks of both sequences. Source parameters were then derived from the three-component records of 28 well-recorded events with seismic moment in the range 8.5 × 1010–1.0 × 1014 Nm. Stress drops ranged in the interval 0.3–52.3 bar and source radii were of the order of 100 m. Their scaling relations are in good agreement with other results derived from the analysis of other Italian earthquakes that occurred in regions of predominantly normal faulting tectonics (Apennines and Calabrian arc). 相似文献
163.
Giuseppe Cello Giovanni Deiana Luca Ferelli Leonardo Marchegiani Laura Maschio Stefano Mazzoli Alessandro Michetti Leonello Serva Emanuele Tondi Tiziano Vittori 《Journal of Seismology》2000,4(4):357-364
On September 26, 1997, at 00.33 h(GMT), a Mw 5.7 earthquake occurred in the axial zone of theUmbria-Marche Apennines of central Italy, in the Colfiorito basin area. At09.40 h (GMT), a Mw 6.0 earthquake again struck the area withinthe Colfiorito basin, a major intramontane basin filled with Quaternarycontinental deposits. The two main shocks, and the associated aftershockswere within a roughly NNW-SSE trending zone of largest damage (Imax10), in which ground deformation has been observed. Along this trend,Cello et al. (1997a) had mapped a few capable faults, showingtranstensional to pure extensional kinematics. Field inspection of themapped faults, carried out after the main shocks, revealed that some ofthem were locally reactivated (for lengths of several hundreds metres andsurface slip in the range of 2–8 cm) during the September 26, 1997earthquakes. 相似文献
164.
Antonella Amoruso Luca Crescentini Marco Petitta Sergio Rusi Marco Tallini 《水文研究》2011,25(11):1754-1764
The Mw = 6·3 L'Aquila earthquake on 6 April 2009 produced a mainshock that caused significant changes in the hydrogeology of the Gran Sasso carbonate fractured aquifer: (i) the sudden disappearance at the time of the mainshock of some springs located exactly along the surface trace of the Paganica normal fault (PF); (ii) an immediate increase in the discharge of the Gran Sasso highway tunnel drainages and of other springs and (iii) a progressive increase of the water table elevation at the boundary of the Gran Sasso aquifer during the following months. Using the data collected since the 1990s that include aftershock monitoring as well as data regarding spring discharge, water table elevations, turbidity and rainfall events, a conceptual model of the earthquake's consequences on the Gran Sasso aquifer is proposed herein. In this model that excludes the contribution of seasonal recharge, the short‐term hydrologic effects registered immediately after the mainshock are determined to have been caused by a pore pressure increase related to aquifer deformation. Mid‐term effects observed in the months following the mainshock suggest that there was a change in groundwater hydrodynamics. Supplementary groundwater that flows towards aquifer boundaries and springs in discharge areas reflects a possible increase in hydraulic conductivity in the recharge area, nearby the earthquake fault zone. This increase can be attributed to fracture clearing and/or dilatancy. Simulations by numerical modelling, related to pore pressure and permeability changes with time, show results in accordance with observed field data, supporting the conceptual model and confirming the processes that influenced the answer of the Gran Sasso aquifer to the L'Aquila earthquake. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
165.
Confidence interval of real‐time forecast stages provided by the STAFOM‐RCM model: the case study of the Tiber River (Italy) 下载免费PDF全文
Silvia Barbetta Tommaso Moramarco Luca Brocca Marco Franchini Florisa Melone 《水文研究》2014,28(3):729-743
This study proposes a statistically based procedure to quantify the confidence interval (CI) to be associated to the stages forecast by a simple model called STAge FOrecasting Model‐Rating Curve Model (STAFOM‐RCM). This model can be used for single river reaches characterized by different intermediate drainage areas and mean wave travel times when real‐time stage records, cross section surveys and rating curves are available at both ends. The model requires, at each time of forecast, an estimate of the lateral contribution qfor between the two sections delimiting the reach. The CI of the stage is provided by analyzing the statistical properties of model output in terms of lateral flow, and it is derived from the CI of the lateral contribution qfor which, in turn, is set up by associating to each qfor the qopt which allows STAFOM‐RCM to reproduce the exact observed stage. From an operative point of view, the qfor values are ranked in order of magnitude and subdivided in classes where the qopt values can be represented through normal distributions of proper mean and variance from which an interval of selected confidence level for qfor is computed and transferred to the stage. Three river reaches of the Tiber river, in central Italy, are used as case study. A sensitivity analysis is also performed in order to identify the minimum calibration set of flood events. The CIs obtained are consistent with the level of confidence selected and have practical utility. An interesting aspect is that different CI widths can be produced for the same forecast stage since they depend on the estimate of qfor made at the time of forecast. Overall, the proposed procedure for CI estimate is simple and can be conveniently adapted for other forecasting models provided that they have physically based parameters which need to be updated during the forecast. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
166.
Antonio Jesús Espejo‐Pérez Luca Brocca Tommaso Moramarco Juan V. Giráldez John Triantafilis Karl Vanderlinden 《水文研究》2016,30(23):4339-4352
Olive cultivation is a widespread land use in Mediterranean climates. The proper implementation of soil and water conservation practices in groves requires detailed knowledge of the governing hydrological processes. In this work topsoil moisture dynamics under wet and dry conditions and across a small catchment was investigated in the inter row (IR) and directly under the olive tree canopies (UC). We do this using a sensor network (11 stations) and a simple bucket model which was calibrated (June, 2011–2012) and validated (June, 2012–2013). During most of the year the normalized soil moisture contents (s) were greater in the IR than under UC, with an average normalized soil moisture difference of 0.12. The difference between UC and IR normalized soil moisture followed a seasonal pattern, reaching a maximum near 0.30 during spring. An analysis of the normalized soil moisture probability density functions (pdfs) was bimodal, showing characteristic dominant wet and dry soil moisture states, with the highest probability densities for the dry state. Overall the spatial variability of soil moisture was lower UC than in the IR. This was a result of the soil moisture buffering capacity of the canopy with respect to rainfall and evaporation, in addition to observed differences in soil properties. Hourly soil moisture data were successfully modelled (R2 > 0.85), both UC and in the IR, yet with the inclusion of a simple formulation for canopy interception for the former. The results provide insight into how olive trees change hydrological processes in their neighbourhood. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
167.
Antonio Dematteis Luca Soldo 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2015,9(4):250-260
ABSTRACTIn this paper recent improvements of the R-Index method are presented, based on its application on several projects in various geological and geotechnical contexts. The R-Index derives from a probabilistic procedure conceived for estimating the reliability level of the Geological and Geotechnical Design Model used to design underground structures, especially tunnels. The R-Index takes into account the geological complexity of a site and recommended empirical scores (based on expert judgement) for different quality levels of geological surveys and geotechnical and geophysical investigations. 相似文献
168.
Chi Ma Jinping Hu Martin D. Suttle Yunbin Guan Thomas G. Sharp Paul D. Asimow Paul J. Steinhardt Luca Bindi 《Meteoritics & planetary science》2023,58(11):1642-1653
A recently described micrometeorite from the Nubian desert (Sudan) contains an exotic Al-Cu-Fe assemblage closely resembling that observed in the Khatyrka chondrite (Suttle et al., 2019; Science Reports 9:12426). We here extend previous investigations of the geochemical, mineralogical, and petrographic characteristics of the Sudan spherule by measuring oxygen isotope ratios in the silicate components and by nano-scale transmission electron microscopy study of a focused ion beam foil that samples the contact between Al-Cu alloys and silicates. O-isotope work indicates an affinity to either OC or CR chondrites, while ruling out a CO or CM precursor. When combined with petrographic evidence we conclude that a CR chondrite parentage is the most likely origin for this micrometeorite. SEM and TEM studies reveal that the Al-Cu alloys mainly consist of Al metal, stolperite (CuAl), and khatyrkite (CuAl2) together with inclusions in stolperite of a new nanometric, still unknown Al-Cu phase with a likely nominal Cu3Al2 stoichiometry. At the interface between the alloy assemblage and the surrounding silicate, there is a thin layer (200 nm) of almost pure MgAl2O4 spinel along with well-defined and almost perfectly spherical metallic droplets, predominantly iron in composition. The study yields additional evidence that Al-Cu alloys, the likely precursors to quasicrystals in Khatyrka, occur naturally. Moreover, it implies the existence of multiple pathways leading to the association in reduced form of these two elements, one highly lithophile and the other strongly chalcophile. 相似文献
169.
Lorenzo Picco Luca Mao Riccardo Rainato Mario A. Lenzi 《Geografiska Annaler: Series A, Physical Geography》2014,96(1):83-97
River islands are defined as discrete areas of woodland vegetation surrounded by either water‐filled channels or exposed gravel. They exhibit some stability and are not submerged during bank‐full flows. The aim of the study is to analyze the dynamics of established, building, and pioneer islands in a 30‐km‐long reach of the gravel‐bed Piave River, which has suffered from intense and multiple human impacts. Plan‐form changes of river features since 1960 were analyzed using aerial photographs, and a LiDAR was used to derive the maximum, minimum and mean elevation of island surfaces, and maximum and mean height of their vegetation. The results suggest that established islands lie at a higher elevation than building and pioneer islands, and have a thicker layer of fine sediments deposited on their surface after big floods. After the exceptional flood in 1966 (RI > 200 years) there was a moderate increase in island numbers and extension, followed by a further increase from 1991, due to a succession of flood events in 1993 and 2002 with RI > 10 years, as well as a change in the human management relating to the control of gravel‐mining activities. The narrowing trend (1960–1999) of the morphological plan form certainly enhanced the chance of islands becoming established and this explains the reduction of the active channel, the increase in established islands and reduction of pioneer islands. 相似文献
170.
Luca Caricchi Anne Pommier Mattia Pistone Jonathan Castro Alain Burgisser Diego Perugini 《Bulletin of Volcanology》2011,73(9):1245-1257
Experiments have been performed to determine the effect of deformation on degassing of bubble-bearing melts. Cylindrical specimens
of phonolitic composition, initial water content of 1.5 wt.% and 2 vol.% bubbles, have been deformed in simple-shear (torsional
configuration) in an internally heated Paterson-type pressure vessel at temperatures of 798–848 K, 100–180 MPa confining pressure
and different final strains. Micro-structural analyses of the samples before and after deformation have been performed in
two and three dimensions using optical microscopy, a nanotomography machine and synchrotron tomography. The water content
of the glasses before and after deformation has been measured using Fourier Transform Infrared Spectroscopy (FTIR). In samples
strained up to a total of γ ∼ 2 the bubbles record accurately the total strain, whereas at higher strains (γ ∼ 10) the bubbles
become very flattened and elongate in the direction of shear. The residual water content of the glasses remains constant up
to a strain of γ ∼ 2 and then decreases to about 0.2 wt.% at γ ∼ 10. Results show that strain enhances bubble coalescence
and degassing even at low bubble volume-fractions. Noticeably, deformation produced a strongly water under-saturated melt.
This suggests that degassing may occur at great depths in the volcanic conduit and may force the magma to become super-cooled
early during ascent to the Earth’s surface potentially contributing to the genesis of obsidian. 相似文献