Mechanisms linking active rock glaciers and impounded surface water formation in high‐mountain areas          下载免费PDF全文

Nicola Colombo  Luigi Sambuelli  Cesare Comina  Chiara Colombero  Marco Giardino  Stephan Gruber  Gaetano Viviano  Livia Vittori Antisari  Franco Salerno 《地球表面变化过程与地形》2018,43(2):417-431

Rock glaciers are slowly flowing mixtures of debris and ice occurring in mountains. They can represent a reservoir of water, and melting ice inside them can affect surface water hydrochemistry. Investigating the interactions between rock glaciers and water bodies is therefore necessary to better understand these mechanisms. With this goal, we elucidate the hydrology and structural setting of a rock glacier–marginal pond system, providing new insights into the mechanisms linking active rock glaciers and impounded surface waters. This was achieved through the integration of waterborne geophysical techniques (ground penetrating radar, electrical resistivity tomography and self‐potentials) and heat tracing. Results of these surveys showed that rock glacier advance has progressively filled the valley depression where the pond is located, creating a dam that could have modified the level of impounded water. A sub‐surface hydrological window connecting the rock glacier to the pond was also detected, where an inflow of cold and mineralised underground waters from the rock glacier was observed. Here, greater water contribution from the rock glacier occurred following intense precipitation events during the ice‐free season, with concomitant increasing electrical conductivity values. The outflowing dynamic of the pond is dominated by a sub‐surface seepage where a minor fault zone in bedrock was found, characterised by altered and highly‐fractured rocks. The applied approach is evaluated here as a suitable technique for investigating logistically‐complex hydrological settings which could be possibly transferred to wider scales of investigation. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

2012 Emilia earthquake,Italy: reinforced concrete buildings response   总被引：1，自引：1，他引：0  

Gaetano Manfredi  Andrea Prota  Gerardo Mario Verderame  Flavia De Luca  Paolo Ricci 《Bulletin of Earthquake Engineering》2014,12(5):2275-2298

Data of the Italian National Institute of Statistics are collected aimed at characterizing Reinforced Concrete (RC) building stock of the area struck by the 2012 Emilia earthquake (number of storeys, age of construction, structural typology). Damage observations, collected right after the event in reconnaissance reports, are shown and analyzed emphasizing typical weaknesses of RC buildings in the area. The evolution of seismic classification for Emilia region and RC buildings’ main characteristics represent the input data for the assessment of non-structural damage of infilled RC buildings, through a simplified approach (FAST method), based on EMS-98 damage scale. Peak Ground Acceleration (PGA) capacities for the first three damage states of EMS-98 are compared with registered PGA in the epicentral area. Observed damage and damage states evaluated for the PGA of the event, in the epicentral area, are finally compared. The comparison led to a fair agreement between observed and numerical data.  相似文献   

Hydrogen emissions from Erebus volcano, Antarctica     

Yves Moussallam  Clive Oppenheimer  Alessandro Aiuppa  Gaetano Giudice  Manuel Moussallam  Philip Kyle 《Bulletin of Volcanology》2012,74(9):2109-2120

The continuous measurement of molecular hydrogen (H₂) emissions from passively degassing volcanoes has recently been made possible using a new generation of low-cost electrochemical sensors. We have used such sensors to measure H₂, along with SO₂, H₂O and CO₂, in the gas and aerosol plume emitted from the phonolite lava lake at Erebus volcano, Antarctica. The measurements were made at the crater rim between December 2010 and January 2011. Combined with measurements of the long-term SO₂ emission rate for Erebus, they indicate a characteristic H₂ flux of 0.03?kg s^–1 (2.8?Mg? day^–1). The observed H₂ content in the plume is consistent with previous estimates of redox conditions in the lava lake inferred from mineral compositions and the observed CO₂/CO ratio in the gas plume (～0.9 log units below the quartz–fayalite–magnetite buffer). These measurements suggest that H₂ does not combust at the surface of the lake, and that H₂ is kinetically inert in the gas/aerosol plume, retaining the signature of the high-temperature chemical equilibrium reached in the lava lake. We also observe a cyclical variation in the H₂/SO₂ ratio with a period of ～10?min. These cycles correspond to oscillatory patterns of surface motion of the lava lake that have been interpreted as signs of a pulsatory magma supply at the top of the magmatic conduit.  相似文献   

Multidisciplinary inferences on a newly recognized active east‐dipping extensional system in Central Italy          下载免费PDF全文

Giusy Lavecchia  Guido Maria Adinolfi  Rita de Nardis  Federica Ferrarini  Daniele Cirillo  Francesco Brozzetti  Raffaella De Matteis  Gaetano Festa  Aldo Zollo 《地学学报》2017,29(1):77-89

We use a multidisciplinary approach to gather preliminary evidence for a Quaternary east‐dipping extensional detachment in Central Italy. This structure crops out in the Sabini‐Eastern Simbruini (SES) and would be hidden at mid‐crustal depths beneath the L'Aquila 2009 (M_w6.3) epicentral area. The SES geometry is reconstructed through geological mapping, structural analysis and seismic line interpretation. The geometry of the mid‐crustal segment, referred to as the Ocre Segment (OS), is interpreted through seismological analyses of the largest aftershock (M_w5.4) of the L'Aquila 2009 sequence. The kinematic compatibility between the SES and the OS under a common SW–NE tensional field is tested through stress inversion of both geological and seismological data. The reliability of OS activation is tested through slip tendency analysis. Like other Italian cases, the SES and the OS are preliminarily interpreted as expressions at different depths of the same unknown east‐dipping extensional detachment, characterized by a ramp–flat–ramp geometry.  相似文献   

Disaggregation-based response weighting scheme for seismic risk assessment of structures     

Ludovica Elefante  Fatemeh JalayerIunio Iervolino  Gaetano Manfredi 《Soil Dynamics and Earthquake Engineering》2010

The results of seismic hazard disaggregation can be used to assign relative weights to a given ground motion record based on its corresponding magnitude, distance and deviation from the ground motion prediction model (epsilon) in order to make probability-based seismic assessments using non-linear dynamic analysis. In this paper, the implications of using the weighted ground motion records are investigated in terms of the mean annual frequency of exceedance of the critical component-based demand to capacity ratio in an existing reinforced concrete structure using both the peak ground acceleration and the first-mode spectral acceleration as intensity measures. It is demonstrated how site-specific seismic hazard disaggregation can be used in order to obtain the conditional probability distribution for a relevant ground motion characteristic given the chosen intensity measure. Distinguished by the amount of structural analysis required, two alternative non-linear dynamic analysis procedures, namely the cloud and the stripes method are implemented. The weighted cloud and the weighted stripes methods are then introduced as analysis procedures which modify the structural response to the selected ground motion records by employing the information provided from the seismic hazard analysis. It is demonstrated that the resulting annual frequencies based on weighted records are comparable to those obtained by using vector-valued intensity measures, while requiring less computational effort.  相似文献   

Ultimate chord rotation of RC columns with smooth bars: some considerations about EC8 prescriptions   总被引：2，自引：2，他引：0  

Gerardo M. Verderame  Paolo Ricci  Gaetano Manfredi  Edoardo Cosenza 《Bulletin of Earthquake Engineering》2010,8(6):1351-1373

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Procedures for calibration of linear models for damage limitation in design of masonry‐infilled RC frames          下载免费PDF全文

Paolo Ricci  Maria Teresa De Risi  Gerardo Mario Verderame  Gaetano Manfredi 《地震工程与结构动力学》2016,45(8):1315-1335

Recent earthquakes have confirmed the role played by infills in the seismic response of reinforced concrete buildings. The control and limitation of damage to such nonstructural elements is a key issue in performance‐based earthquake engineering. The present work is focused on modeling and analysis of damage to infill panels, and, in particular, it is aimed towards linear analysis procedures for assessing the damage limitation limit state of infilled reinforced concrete frames. First, code provisions on infill modeling and acceptance criteria at the damage limitation limit state are reviewed. Literature contributions on damage to unreinforced masonry infill panels and corresponding displacement capacity are reported and discussed. Two procedures are then proposed aiming at a twofold goal: (i) the determination of ‘equivalent’ interstory drift ratio limits for a bare frame model and (ii) the estimation of the stiffness of equivalent struts representing infill walls in a linear model. These two quantities are determined such that a linear model ensures a reliable estimation of seismic capacity at the damage limitation limit state, providing the same intensity level as that obtained from nonlinear analyses carried out on structural models with infills. Finally, the proposed procedures are applied to four‐story and eight‐story case study‐infilled frames, designed for seismic loads according to current technical codes. The results of these application examples are presented and discussed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Hysteretic cyclic response of concrete columns reinforced with smooth bars   总被引：1，自引：1，他引：0  

Kamyar Karbasi Arani  Mohammad S. Marefat  Marco Di Ludovico  Andrea Prota  Gaetano Manfredi 《Bulletin of Earthquake Engineering》2013,11(6):2033-2053

The application of smooth (plain) bars in reinforced concrete (RC) construction has been abandoned since the 1970s; however, there are many old reinforced concrete buildings in the world whose construction is based on this old style that are now in need of structural seismic rehabilitation according to the requirements of present day seismic rehabilitation codes. The focus of this study concerns the investigation of the hysteretic cyclic response of RC columns with smooth bars. The results of six column specimens having a variety of details for overlapping splices of longitudinal bars while experiencing two different levels of axial loads under cyclic loading reversals are presented. Through analysis of test observations and the obtained experimental results, it is attempted to clarify major aspects of hysteretic response for RC columns with smooth bars, from a seismic assessment point of view. The hysteretic force–drift responses of columns are deeply investigated and a new concept explaining the flag shape form of the hysteretic response is presented. Furthermore, the rocking response of columns is predicted with a new formulation that assumes an internal compression strut inside the column body as a consequence of rocking that originated from high base rotations. Finally, a simple hysteresis rule is proposed which is the result of considering the combination of two springs in parallel to provide the total hysteretic response as the summation of rocking hysteretic and bottom anchor (smooth bar) hysteretic responses.  相似文献   

GIS-based subsurface databases and 3-D geological modeling as a tool for the set up of hydrogeological framework: Nabeul–Hammamet coastal aquifer case study (Northeast Tunisia)     

Fatma Trabelsi  Jamila Tarhouni  Abdallah Ben Mammou  Gaetano Ranieri 《Environmental Earth Sciences》2013,70(5):2087-2105

The subsurface data are a basic requirement for the set up of hydrogeological framework. Geographic information systems (GIS) tools have proved their usefulness in hydrogeology over the years which allow for management, synthesis, and analysis of a great variety of subsurface data. However, standard multi-layered systems are quite limited for modeling, visualizing, and editing subsurface data and geologic objects and their attributes. This paper presents a methodology to support the implementation of hydrogeological framework of the multi-layered aquifer system in Nabeul–Hammamet (NH) coastal region (NE, Tunisia). The methodology consists of (1) the development of a complete and generally accepted hydrogeological classification system for NH aquifer system (2) the development of relational databases and subsequent GIS-based on geological, geophysical and hydrogeological data, and (3) the development of meaningful three-dimensional geological and aquifer models, using GIS subsurface software, RockWorks 2002. The generated 3-D geological models define the lithostratigraphy and the geometry of each depositional formation of the region and delineate major aquifers and aquitards. Where results of the lithologic model revealed that there is a wide range of hydraulic conductivities in the modeled area, which vary spatially and control the groundwater flow regime. As well, 17 texturally distinct stratigraphic units were identified and visualized in the stratigraphic model, while the developed aquifer model indicates that the NH aquifer system is composed of multi-reservoir aquifers subdivided in aquifers units and separated by sandy clay aquitards. Finally, this study provides information on the storing, management and modeling of subsurface spatial database. GIS has become a useful tool for hydrogeological conceptualization and groundwater management purposes and will provide necessary input databases within different groundwater numerical models.  相似文献   

Microstructural Investigation of Naturally Deformed Leucogneiss from an Alpine Shear Zone (Southern Calabria – Italy)     

Rosolino Cirrincione  Eugenio Fazio  Patrizia Fiannacca  Gaetano Ortolano  Rosalda Punturo 《Pure and Applied Geophysics》2009,166(5-7):995-1010

In order to reveal any correlation between the preferred orientation of quartz and progressive intensity of strain, a suite of deformed leucogneiss collected within a ductile shear zone outcropping in Calabria (southern Italy) was investigated. Based on the microstructural approach and matrix-clast relationships, the method applied here may be useful for appraising the connection between deformation mechanisms of constituent minerals and bulk textural properties of naturally sheared rocks. Accordingly, quartz c-axis orientation patterns were determined by image-assisted analysis. Results revealed a correlation between finite strain and textural features: As strain increases, the matrix develops at the expense of the clast counterpart, which is instead progressively reduced in both size and amount.  相似文献