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141.
In this study the damage suffered by churches during the 2012 Emilia seismic sequence in Italy is analysed, based on surveys and inspections carried out in the area. Similarly to what was observed after other Italian earthquakes, the damage to churches was severe. However, the Emilia churches present some characteristic features such as the use of unreinforced clay brick masonry. In order to appropriately address the performance of this class of buildings, typical architectural layouts and construction techniques are described. Such techniques are interpreted also in the light of the local seismic catalogue. Fifty churches are then selected and their damage is studied, with reference to typical local-collapse mechanisms of different macro-elements. The study highlights that the damage is often concentrated at the top section of the façade, in the clerestory walls, in the vaults and in the bell towers. Structural analyses are performed to explain some of the observations. The overturning of the top section of the façade is analytically addressed, modelling the friction interlocking. With reference to the case study of San Francesco in Mirandola, non-linear static and dynamic analyses allow us to correlate the directionality of damage to the higher seismic demand along the NS direction, to point out the negligible role of the large vertical component of ground motion and to emphasise the relevance of the buttresses for the seismic response of the façade.  相似文献   
142.
143.
Between 2001 and 2005, a large debris rock slide occurred on the western slope of the Cordillera de Santa Cruz in the southeast Andean corner of the Province of San Juan (31°40′ S–70°16′ W). The landslide material accumulated in a downstream gorge as a natural dam of the Santa Cruz river, forming a large-volume lake. In November 2005, probably as a result of the increasing pressure of the water volume, this natural dam breached off with a violent and unexpected flash flood. In addition to life-threatening instances lived by some people downstream, this flood caused great economic loss to main localities of the Department of Calingasta, as well as considerable damage to one of the most relevant projects of the Province, the Caracoles Hydropower Project dam on the San Juan river. Considering the high costs of any physical remediation for a natural dam located in this high, remote, and inaccessible mountain area with no reliable road access, the main protective measures left to be pondered are the installation of a flash-flood early-warning system connected to downstream localities, along with a program of hydrological monitoring at the dam-forming area and annual satellital monitoring to verify the evolution of accumulated mass movements.  相似文献   
144.
Use of eddy covariance (EC) techniques to map the spatial distribution of diffuse volcanic CO2 fluxes and quantify CO2 emission rate was tested at the Horseshoe Lake tree-kill area on Mammoth Mountain, California, USA. EC measurements of CO2 flux were made during September–October 2010 and ranged from 85 to 1,766 g m−2 day−1. Comparative maps of soil CO2 flux were simulated and CO2 emission rates estimated from three accumulation chamber (AC) CO2 flux surveys. Least-squares inversion of measured eddy covariance CO2 fluxes and corresponding modeled source weight functions recovered 58–77% of the CO2 emission rates estimated based on simulated AC soil CO2 fluxes. Spatial distributions of modeled surface CO2 fluxes based on EC and AC observations showed moderate to good correspondence (R 2 = 0.36 to 0.70). Results provide a framework for automated monitoring of volcanic CO2 emissions over relatively large areas.  相似文献   
145.
By using BET_VH, we propose a quantitative probabilistic hazard assessment for base surge impact in Auckland, New Zealand. Base surges resulting from phreatomagmatic eruptions are among the most dangerous phenomena likely to be associated with the initial phase of a future eruption in the Auckland Volcanic Field. The assessment is done both in the long-term and in a specific short-term case study, i.e. the simulated pre-eruptive unrest episode during Exercise Ruaumoko, a national civil defence exercise. The most important factors to account for are the uncertainties in the vent location (expected for a volcanic field) and in the run-out distance of base surges. Here, we propose a statistical model of base surge run-out distance based on deposits from past eruptions in Auckland and in analogous volcanoes. We then combine our hazard assessment with an analysis of the costs and benefits of evacuating people (on a 1 × 1-km cell grid). In addition to stressing the practical importance of a cost-benefit analysis in creating a bridge between volcanologists and decision makers, our study highlights some important points. First, in the Exercise Ruaumoko application, the evacuation call seems to be required as soon as the unrest phase is clear; additionally, the evacuation area is much larger than what is recommended in the current contingency plan. Secondly, the evacuation area changes in size with time, due to a reduction in the uncertainty in the vent location and increase in the probability of eruption. It is the tradeoff between these two factors that dictates which cells must be evacuated, and when, thus determining the ultimate size and shape of the area to be evacuated.  相似文献   
146.
From 2009 to 2011, marine spatial planning (MSP) rapidly gained visibility in the United States as a promising ocean management tool. A few small-scale planning efforts were completed in state waters, and the Obama Administration proposed a framework for large-scale regional MSP throughout the U.S. Exclusive Economic Zone. During that same time period, the authors engaged a variety of U.S ocean stakeholders in a series of dialogs with several goals: to share information about what MSP is or could be, to hear stakeholder views and concerns about MSP, and to foster better understanding between those who depend on ocean resources for their livelihood and ocean conservation advocates. The stakeholder meetings were supplemented with several rounds of in-depth interviews and a survey. Despite some predictable areas of conflict, project participants agreed on a number of issues related to stakeholder engagement in MSP: all felt strongly that government planners need to engage outsiders earlier, more often, more meaningfully, and through an open and transparent process. Equally important, the project affirmed the value of bringing unlike parties together at the earliest opportunity to learn, talk, and listen to others with whom they rarely engage.  相似文献   
147.
Turbidity currents and their deposits can be investigated using several methods, i.e. direct monitoring, physical and numerical modelling, sediment cores and outcrops. The present study focused on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in eleven clusters of closely spaced thin beds. Depositional processes and sources for three of those eleven clusters are studied at three coring sites. Bathymetrical data and seismic reflection profiles are used to understand the specific geomorphology of each site. X‐ray, thin sections and CT scan imagery combined with grain‐size, geochemical and mineralogical measurements on the cores allow characterization of the turbidites. Turbidites included in each cluster were produced by remobilization of surficial slope sediment, a process identified in very few studies worldwide. Three types of turbidites are distinguished and compared with deposits obtained in flume studies published in the literature. Type 1 is made of an ungraded clayey silt layer issued from a cohesive flow. Type 2 is composed of a partially graded clayey sand layer overlain by a mud cap, attributed to a transitional flow. Type 3 corresponds to a graded clayey sand layer overlain by a mud cap issued from a turbulence‐dominated flow. While the published experimental studies show that turbulence is damped by cohesion for low clay content, type 3 deposits of this study show evidence for a turbulence‐dominated mechanism despite their high clay content. This divergence may in part relate to input variables, such as water chemistry and clay mineralogy, that are not routinely considered in experimental studies. Furthermore, the large sedimentological variety observed in the turbidites from one coring site to another is related to the evolution of a sediment flow within a field‐scale basin made of a complex physiography that cannot be tackled by flume experiments.  相似文献   
148.
For the Quaternary and Neogene, aragonitic biogenic and abiogenic carbonates are frequently exploited as archives of their environment. Conversely, pre‐Neogene aragonite is often diagenetically altered and calcite archives are studied instead. Nevertheless, the exact sequence of diagenetic processes and products is difficult to disclose from naturally altered material. Here, experiments were performed to understand biogenic aragonite alteration processes and products. Shell subsamples of the bivalve Arctica islandica were exposed to hydrothermal alteration. Thermal boundary conditions were set at 100°C, 175°C and 200°C. These comparably high temperatures were chosen to shorten experimental durations. Subsamples were exposed to different 18O‐depleted fluids for durations between two and twenty weeks. Alteration was documented using X‐ray diffraction, cathodoluminescence, fluorescence and scanning electron microscopy, as well as conventional and clumped isotope analyses. Experiments performed at 100°C show redistribution and darkening of organic matter, but lack evidence for diagenetic alteration, except in Δ47 which show the effects of annealing processes. At 175°C, valves undergo significant aragonite to calcite transformation and neomorphism. The δ18O signature supports transformation via dissolution and reprecipitation, but isotopic exchange is limited by fluid migration through the subsamples. Individual growth increments in these subsamples exhibit bright orange luminescence. At 200°C, valves are fully transformed to calcite and exhibit purple‐blue luminescence with orange bands. The δ18O and Δ47 signatures reveal exchange with the aqueous fluid, whereas δ13C remains unaltered in all experiments, indicating a carbonate‐buffered system. Clumped isotope temperatures in high‐temperature experiments show compositions in broad agreement with the measured temperature. Experimentally induced alteration patterns are comparable with individual features present in Pleistocene shells. This study represents a significant step towards sequential analysis of diagenetic features in biogenic aragonites and sheds light on reaction times and threshold limits. The limitations of a study restricted to a single test organism are acknowledged and call for refined follow‐up experiments.  相似文献   
149.
In the Garhwal of Uttarakhand, India, the Bhotiya, an ethnically and culturally distinct tribal group, were historically engaged in seasonal migration (i.e. transhumance) to take advantage of scarce mountain resources and trade relations with Tibet. This livelihood practice has all but disappeared. Households are adapting to these changing circumstances by engaging in the collection and sale of the valuable alpine medicinal fungus Ophiocordyceps sinensis, widely known as Cordyceps. The collection of this fungus has exploded, emerging as a lucrative yet high-risk livelihood strategy for many Bhotiya communities. The Bhotiyas’ historic herding and trade-based interactions and knowledge of these alpine environments where Cordyceps are found uniquely positions them to access this valuable biological resource. Elsewhere in the Himalayan region, some households are earning as much as two-thirds of their income from the collection of Cordyceps; in China Cordyceps is now listed as an endangered species due to intense over-exploitation in the Tibetan Plateau. This paper seeks to fill the void in the scientific literature on the social, ecological and economic aspects of the emerging Cordyceps trade in the Garhwal. Our study investigates the socio-spatial dimensions of Cordyceps collection in the high alpine meadows. We document how a fusion of local knowledge and practice with alpine mountain systems has served to reinvigorate the economic integrity of mountain communities at a time of rapid socio-economic change and to reimagine a new relationship between alpine resources and community well-being. The article offers suggestions to address the sustainability of both Cordyceps collection and livelihood activities which hinge on this fungus population. We find a need for (1) community-based conservation measures that are rooted in (2) secure resource access rights for local communities to continue sustainable collection and sale of Cordyceps and (3) participatory-and science-based processes for determining appropriate local collection numbers.  相似文献   
150.
In this paper, we explore the effects of the intrinsic uncertainties upon long-term volcanic hazard by analyzing tephra fall hazard at Campi Flegrei, Italy, using the BET_VH model described in Marzocchi et al. (Bull Volcanol, 2010). The results obtained show that volcanic hazard based on the weighted average of all possible eruptive settings (i.e. size classes and vent locations) is significantly different from an analysis based on a single reference setting, as commonly used in volcanic hazard practice. The long-term hazard map for tephra fall at Campi Flegrei obtained here accounts for a wide spectrum of uncertainties which are usually neglected, largely reducing the bias intrinsically introduced by the choice of a specific reference setting. We formally develop and apply a general method to recursively integrate simulations from different models which have different characteristics in terms of spatial coverage, resolution and physical details. This outcome of simulations will be eventually merged with field data through the use of the BET_VH model.  相似文献   
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