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A. Cappello M. Neri V. Acocella G. Gallo A. Vicari C. Del Negro 《Bulletin of Volcanology》2012,74(9):2083-2094
We produce a spatial probability map of vent opening (susceptibility map) at Etna, using a statistical analysis of structural features of flank eruptions of the last 2?ky. We exploit a detailed knowledge of the volcano structures, including the modalities of shallow magma transfer deriving from dike and dike-fed fissure eruptions analysis on historical eruptions. Assuming the location of future vents will have the same causal factors as the past eruptions, we converted the geological and structural data in distinct and weighted probability density functions, which were included in a non-homogeneous Poisson process to obtain the susceptibility map. The highest probability of new eruptive vents opening falls within a N-S aligned area passing through the Summit Craters down to about 2,000?m?a.s.l. on the southern flank. Other zones of high probability follow the North-East, East-North-East, West, and South Rifts, the latter reaching low altitudes (~400?m). Less susceptible areas are found around the faults cutting the upper portions of Etna, including the western portion of the Pernicana fault and the northern extent of the Ragalna fault. This structural-based susceptibility map is a crucial step in forecasting lava flow hazards at Etna, providing a support tool for decision makers. 相似文献
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Vincent J. Del Casino Jr. 《The Professional geographer》2013,65(3):407-421
In this article, I contribute to our understanding of the plurality of approaches that construct the geographies of health care through an examination of the distribution of health care services for people living with HIV/AIDS (PLWHA) in Chiang Mai Province, Thailand. In particular, I focus on the development of a network of support groups for PLWHA in order to examine the differences in the sociospatial organization of these groups, the practices of social actors participating in the groups' activities, and how these activities are mediated through place-based social relations. The first section of the article analyzes the spatial distribution of PLWHA support groups in relation to the distribution of AIDS cases over two time periods, 1994 and 1997. The second section goes below the surface of the spatial distribution, examining similarities and differences in PLWHA support groups through an analysis of survey data collected on thirty-five groups in 1997. The final section deepens this examination through an analysis of ethnographic data collected on the outreach efforts of one nongovernmental organization (NGO) and one PLWHA support group with which it worked. Each section offers opportunities for the extension of our understanding of the development of PLWHA support groups, their distribution in relation to the spread of AIDS cases, and their place-based meanings. 相似文献
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Abstract Recently Andrews has discussed an example of a topographically-forced non-zonal now satisfying the Arnold-Blumen sufficient condition for stability. At large distances from the topographic centre this flow becomes purely zonal and westward. After underlining the richness of solutions of the Andrews model, the present paper goes on to show that Andrews' technique can be applied successfully to a model where the vertical profile of static stability resembles those found in the ocean. In particular we obtain a large class of hydrodynamic stable flows, forced by the bottom topography, for continuously stratified fluids (two layers each with uniform Brunt-Väisälä frequency). 相似文献
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Rémy Thibaud Géraldine Del Mondo Thierry Garlan Ariane Mascret Christophe Carpentier 《Transactions in GIS》2013,17(5):742-762
Defining a model for the representation and the analysis of spatio‐temporal dynamics remains an open domain in geographical information sciences. In this article we investigate a spatio‐temporal graph‐based model dedicated to managing and extracting sets of geographical entities related in space and time. The approach is based on spatial and temporal local relations between neighboring entities during consecutive times. The model allows us to extract sets of connected entities distant in time and space over long periods and large spaces. From GIS concepts and qualitative reasoning on space and time, we combine the graph model with a dedicated spatial database. It includes information on geometry and geomorphometric parameters, and on spatial and temporal relations. This allows us to extend classical measurements of spatial parameters, with comparisons of entities linked by complex relations in space and time. As a case study, we show how the model suggests an efficient representation of dunes dynamics on a nautical chart for safe navigation. 相似文献
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Tiziana Di Lorenzo Mauro Brilli Dina Del Tosto Diana M. P. Galassi Marco Petitta 《Environmental Earth Sciences》2012,67(8):2383-2398
The aim of this study is to apply an integrated approach to determine nitrate sources and fate in the alluvial aquifer of the River Vibrata (Abruzzi, central Italy) by coupling the Isotope and the Component approaches. Collected data include concentration and nitrogen isotope composition of groundwater samples from the alluvial aquifer and nitrogen loads arising from agricultural and non-agricultural sources. The adopted methodology identified synthetic fertilizers as main sources of nitrate in the Vibrata alluvial aquifer. At the catchment scale, two different zones have been identified: the Upper Valley, where infiltration to groundwater is dominant and nitrogen easily migrates into the aquifer; in this area, nitrate content in groundwater is stable and normally higher than EU requirements. Moreover, streamwaters are fed by groundwater with a nitrate content likely lowered by denitrification processes occurring in the hyporheic zone. In the Lower Valley, runoff processes dominate and the nitrate content in surface waters is higher. Nevertheless, groundwater is locally affected by denitrification that breaks down the nitrate content, which often reaches values consistent with law limits. 相似文献
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The Aterno valley strong-motion array: seismic characterization and determination of subsoil model 总被引:1,自引:1,他引:0
G. Lanzo M. Tallini G. Milana G. Di Capua F. Del Monaco A. Pagliaroli S. Peppoloni 《Bulletin of Earthquake Engineering》2011,9(6):1855-1875
The paper focuses on the strong motion array deployed in the upper Aterno River Valley, in the immediate outskirts north-west
of the town of L’Aquila, which is part of the Italian Strong Motion Network operated by the Department of Civil Protection.
The array is composed of six accelerometric stations located along a cross section of the valley. The importance of this array
relies on the fact that a large amount of high-quality records were obtained during the 2009 L’Aquila seismic sequence, from
both the mainshock and several aftershocks. These data are especially important to investigate site effects in sediment-filled
valleys during moderate earthquakes in epicentral area because well-documented observational studies are very limited in the
literature. However, the main drawback for the study of site effects in the Aterno valley is the lack of a detailed knowledge
of the geometry of the valley, soil layering and dynamic properties of materials. The main motivation for this study stems
from the need to provide a reliable subsoil model of the valley coupled with high-quality strong motion data. Based on the
above, in the framework of S4 project, a major effort was undertaken to get a trustworthy cross section of the valley by an
ad hoc investigation, comprising geological and geotechnical surveys as well as an extensive geophysical campaign, characterized
by both active and passive measurements. These results were complemented by additional geological and geotechnical data available
in the literature. By merging all the information acquired, a 2D subsoil model of the transversal section of the upper Aterno
valley has been produced. The valley is characterised by an asymmetric shape with a shallower rock basement at the western
edge of the valley that deepens at the valley centre. Moreover, based on the results of geophysical tests, representative
Vs values were assigned to the different lithologic units forming the alluvial deposits filling the valley. Shear wave velocity
is a fundamental parameter for ground response studies and it is also effective in classifying the accelerometric station
from a seismic point of view. The 2D model may be therefore, considered a benchmark model for future studies of site effects.
It will offer the possibility to examine site effects with a complex underlying geology and to validate the results of numerical
simulations of site response analyses with the numerous observations from earthquake recordings, both for weak and strong
ground motion conditions. 相似文献