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   

Performance of non-structural elements in RC buildings during the L��Aquila, 2009 earthquake     

F. Braga  V. Manfredi  A. Masi  A. Salvatori  M. Vona 《Bulletin of Earthquake Engineering》2011,9(1):307-324

In Italy infills and partitions (non-structural elements) are typically made up of hollow brick masonry, disposed in one or two parallel vertical walls. Many studies have analysed their role on the seismic behaviour of moment resisting framed RC buildings and many seismic codes, all over the world, have provided specific additional measures for them. During the Abruzzo seismic sequence, non-structural damage in RC buildings, both private and public, was extensive, varying from small cracks to collapse, along with minor or no damage to structural elements. This damage involved a number of buildings, both old and recently completed, determining heavy socio-economic consequences, including human casualties, loss of building functionality (particularly important in case of strategic constructions), and unusable buildings. In this paper a review of the most frequent damage patterns is performed, aimed at identifying the main causes of damage and linking them to commonly adopted construction rules. For this purpose, local and global structural configurations frequently exhibiting non-structural damage are described, aside from out-of-plane and in-plane failures. Furthermore, a review of code provisions on non structural elements has been performed in the paper making reference to the most prominent current seismic codes and, finally, some design and construction rules are suggested.  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   

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   

Modelling the transverse behaviour of circular tunnels in structured clayey soils during earthquakes     

Cabangon  Lowell Tan  Elia  Gaetano  Rouainia  Mohamed 《Acta Geotechnica》2019,14(1):163-178

Acta Geotechnica - The paper presents novel results from advanced numerical simulations of the transverse behaviour of shallow circular tunnels in natural clays accounting for soil structure...  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   

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   

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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Volcanic soil formation in Calabria (southern Italy): The Cecita Lake geosol in the late Quaternary geomorphological evolution of the Sila uplands     

Fabio Scarciglia  Rosanna De Rosa  Giuseppe Vecchio  Carmine Apollaro  Gaetano Robustelli  Filippo Terrasi 《Journal of Volcanology and Geothermal Research》2008

This paper focuses on the main morphological, physical, chemical and mineralogical features of an andic-like soil, widely outcropping in the Sila upland plateau of Calabria (southern Italy), and its potential role in tephrostratigraphy. A multidisciplinary and multiscale approach allowed identification of this soil as a “masked” distal archive of volcanic products, developed on granite rocks and sediments with a coeval pyroclastic input during pedogenesis. The study demonstrates that the contribution of volcanic parent materials can be successfully hypothesized and assessed even in the absence, limited extent or poor preservation of primary eruptive products. The soil has an Andisol-like appearance, despite laboratory data that do not match the entire suite of diagnostic criteria for the Andisol taxonomic order. Geomorphological, stratigraphic and pedologic results, coupled with tephrostratigraphic and radiometric data, concur to suggest a Late Pleistocene(?) to Holocene age of the Andisol-like soil. In particular, the rhyolitic chemical composition of small-sized glass fragments (identified by SEM–EDS analyses) indicates soil genesis contributed by volcanic ash, probably sourced from Aeolian Arc explosive activity spanning the last 30 ka. Accordingly, the evidence of limited relict clay illuviation and the specific type of pedogenesis allowing the development of andic properties (in turn related to the neoformation of clay minerals from the weathering of volcanic glass) are consistent with a climatic shift from a seasonally-contrasted to a constantly humid pedoenvironment. This change can be ascribed to the Lateglacial(?) or Early–Middle Holocene to Late Holocene transition. Calibrated AMS ¹⁴C dates performed on charcoal fragments sampled from three representative soil profiles, provide Late Holocene ages (3136 ± 19, 343 ± 16 and 92 ± 24 yr BP), in accord with archaeological finds. On the basis of the consistent stratigraphic position, lateral continuity and wide extent, the soil can be considered a good pedostratigraphic marker in the Sila highlands and is informally defined as the “Cecita Lake geosol”. It supplies valuable time constraints for the underlying (occasionally overlying) deposits and/or soils. Moreover, it allows regional-scale morphostratigraphic correlations and detailed reconstruction of Late Pleistocene–Holocene geomorphic events in Calabria, a very suitable region for distal tephra deposition in the central Mediterranean peri-volcanic area. The effects of high-energy volcanic eruptions are interfingered with or superimposed by other geomorphic processes and climatic or anthropogenic signals.  相似文献