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71.
Miriam Colombi Barbara Borzi Helen Crowley Mauro Onida Fabrizio Meroni Rui Pinho 《Bulletin of Earthquake Engineering》2008,6(3):485-504
The concerted effort to collect earthquake damage data in Italy over the past 30 years has led to the development of an extensive
database from which vulnerability predictions for the Italian building stock can be derived. A methodology to derive empirical
vulnerability curves with the aforementioned data is presented herein and the resulting curves have been directly compared
with mechanics-based vulnerability curves. However, it has been found that a valid comparison between the empirical and analytical
vulnerability curves is not possible mainly due to a number of shortcomings in the database of surveyed buildings. A detailed
discussion of the difficulties in deriving vulnerability curves from the current observed damage database is thus also presented. 相似文献
72.
Miriam Baglioni Emiliano Giovannetti Maria Vittoria Masserotti Chiara Renso Laura Spinsanti 《Transactions in GIS》2008,12(Z1):31-44
Querying geographical information systems has been recognized as a difficult task for non‐expert users. Furthermore, user queries are often characterized by semantic aspects not directly managed by traditional spatial databases or GIS. Examples of such semantic geospatial queries are the use of implicit spatial relations between objects, or the reference of domain concepts not explicitly represented in data. To handle such queries, we envisage a system that translates natural language queries into spatial SQL statements on a database, thus improving standard GIS with new semantic capabilities. Within this general objective, the contribution of this article is to introduce a methodology to handle semantic geospatial queries issued over a spatial database. This approach captures semantics from an ontology built upon the spatial database and enriched by domain concepts and properties specifically defined to represent the localization of objects. Some examples of the use of the methodology in the urban domain are presented. 相似文献
73.
Hydrothermal sulfide-sulfate deposits were sampled from eight active and inactive vent sites along the East Pacific Rise at 21°N during the RISE expedition of April, 1979. The mineralogy of the samples has been determined by X-ray diffractometry, scanning electron microscopy, and X-ray energy dispersive analysis. Mounds of Zn, Fe, and Cu sulfides, dominated by sphalerite, pyrite, and lesser chalcopyrite, are topped by inactive and active chimneys, spouting fluids ≤350°C. The outer zones of active chimneys bear abundant anhydrite precipitated from heated ambient seawater, in addition to hydrothermal pyrite and sphalerite. Mg-hydroxysulfate-hydrate, a phase identified in seawater heating experiments, but previously not observed in nature, is intimately intergrown with anhydrite. Hottest chimneys contain massive chalcopyrite±bornite in their interior zones and belch fluids blackened by a presumably non-equilibrium assemblage of pyrrhotite plus minor sphalerite and pyrite. The early, outer walls of chimneys form from sulfates and the sulfide minerals in black smoke, but metastable pyrrhotite in outer zones is rapidly recrystallized to pyrite or marcasite. Reduction in the permeability of the outer walls permits a high-temperature (>~250°C), low-pH environment within chimneys that enhances precipitation of Cu-Fe sulfides in the central zones. Cooler, worm-covered chimneys emit white fluids bearing particulates of amorphous silica, barite, and pyrite. Amorphous silica and barite are also widely associated with fossilized worm-tubes. Two inactive chimneys are filled with sphalerite, wurtzite, sulfur, pyrite, and marcasite. Anhydrite has been dissolved from these dead chimneys, and the sulfate assemblage is dominated by barite and alteration products such as jarosite and natrojarosite. Silicates other than amorphous silica are not abundant in these deposits, although talc forms in hot chimneys from seawater Mg and hydrothermal silica, and nontronite is found in sediments on the crest of the East Pacific Rise. Other accessory phases identified include copper-rich sulfides such as cubanite, chalcocite, covellite, and digenite; galena; Fe-oxyhydroxides, including goethite; and gypsum. Chimney debris accumulates to form basal mounds, and the mineralogical differences between mounds and chimneys are attributable to weathering of mounds. Mn-oxyhydroxides form crusts within a few meters of the vents, but are not coprecipitating with the sulfide/sulfate minerals. 相似文献
74.
The 50% and 90% P-wave detection thresholds of 3 Austrian, 2 Czech, 5 German, 1 Hungarian and 3 Slovak seismic stations have been determined for four intervals of epicentral distances by a direct method using the maximum-likelihood technique. The USGS-NEIC Earthquake Data Reports covering the period from January 1990 to November 1994 were used as the reference system. The seismic stations Kaperské Hory (KHC, Czech Republic) and Collmberg (CLL, Germany) are the stations with the best detection capabilities for all investigated intervals of epicentral distances. 相似文献
75.
Elcia M.S. Brito Robert Duran Marisol Goñi-Urriza Miriam A.C. Crapez Julio C.A. Wasserman 《Marine pollution bulletin》2009,58(3):418-423
Mangroves are sensitive ecosystems of prominent ecological value that lamentably have lost much of their areas across the world. The vulnerability of mangroves grown in proximity to cities requires the development of new technologies for the remediation of acute oil spills and chronic contaminations. Studies on oil remediation are usually performed with in vitro microcosms whereas in situ experiments are rare. The aim of this work was to evaluate oil degradation on mangrove ecosystems using in situ microcosms seeded with an indigenous hydrocarbonoclastic bacterial consortium (HBC). Although the potential degradation of oil through HBC has been reported, their seeding directly on the sediment did not stimulate oil degradation during the experimental period. This is probably due to the availability of carbon sources that are easier to degrade than petroleum hydrocarbons. Our results emphasize the fragility of mangrove ecosystems during accidental oil spills and also the need for more efficient technologies for their remediation. 相似文献
76.
Miriam C. Jones Dorothy M. Peteet Dorothy Kurdyla Thomas Guilderson 《Quaternary Research》2009,72(2):207-217
Analysis of pollen, spores, macrofossils, and lithology of an AMS 14C-dated core from a subarctic fen on the Kenai Peninsula, Alaska reveals changes in vegetation and climate beginning 14,200 cal yr BP. Betula expansion and contraction of herb tundra vegetation characterize the Younger Dryas on the Kenai, suggesting increased winter snowfall concurrent with cool, sunny summers. Remarkable Polypodiaceae (fern) abundance between 11,500 and 8500 cal yr BP implies a significant change in climate. Enhanced peat preservation and the occurrence of wet meadow species suggest high moisture from 11,500 to 10,700 cal yr BP, in contrast to drier conditions in southeastern Alaska; this pattern may indicate an intensification and repositioning of the Aleutian Low (AL). Drier conditions on the Kenai Peninsula from 10,700 to 8500 cal yr BP may signify a weaker AL, but elevated fern abundance may have been sustained by high seasonality with substantial snowfall and enhanced glacial melt. Decreased insolation-induced seasonality resulted in climatic cooling after 8500 cal yr BP, with increased humidity from 8000 to 5000 cal yr BP. A dry interval punctuated by volcanic activity occurred between 5000 and 3500 cal yr BP, followed by cool, moist climate, coincident with Neoglaciation. Tsuga mertensiana expanded after ~ 1500 cal yr BP in response to the shift to cooler conditions. 相似文献
77.
Miriam Baumgartner Ronald J. Bakker Gerald Doppler 《Contributions to Mineralogy and Petrology》2014,168(1):1-14
Re-equilibration processes of natural H2O–CO2–NaCl-rich fluid inclusions quartz are experimentally studied by exposing the samples to a pure H2O external fluid at 600 °C. Experimental conditions are selected at nearly constant pressure conditions (309 MPa) between fluid inclusions and pore fluid, with only fugacity gradients in H2O and CO2, and at differential pressure conditions (394–398 MPa, corresponding to an internal under-pressure) in addition to similar CO2 fugacity gradients and larger H2O fugacity gradients. Modifications of fluid inclusion composition and density are monitored with changes in ice dissolution temperature, clathrate dissolution temperature and volume fraction of the vapour phase at room temperature. Specific modification of these parameters can be assigned to specific processes, such as preferential loss/gain of H2O and CO2, or changes in total volume. A combination of these parameters can clearly distinguish between modifications according to bulk diffusion or deformation processes. Bulk diffusion of CO2 according to fugacity gradients is demonstrated at constant pressure conditions. The estimated preferential loss of H2O is not in accordance with those gradients in both constant pressure and differential pressure experiments. The development of deformation halos in quartz around fluid inclusions that are either under-pressurized or over-pressurized promotes absorption of H2O from the inclusions and inhibits bulk diffusion according to the applied fugacity gradients. 相似文献
78.
Provenance and distribution of tethyan pelagic and hemipelagic siliceous sediments,pindos mountains,Greece 总被引:2,自引:0,他引:2
Miriam Baltuck 《Sedimentary Geology》1982,31(1):63-88
The broad range of time over which ribbon bedded cherts were deposited does not extend into the present marine environment, and no ribbon cherts have been recovered from the sea floor by the Deep Sea Drilling Project. The depositional environment of bedded cherts is difficult to determine, but extra-silicic impurities in the rock may offer clues about the provenance of the non-biogenic component. To test the usefulness of relative abundances of the extra silicic components in extracting information on the depositional environment of the chert, I analyzed the major element chemistry of chert samples from a broad range of environments including ophiolite-associated chert from the Franciscan Formation of California, deep-sea chert and porcellanite from the northwest Pacific (DSDP Leg 32), shallow pelagic shelf chert nodules from the Chalk of Britain, continental marginal basin chert from the Monterey Formation of California, and continental marginal basin chert from the Pindos Zone of Greece. The ratios FeO/A12O3, TiO2/A12O3 and A1/A1+Fe+Mn were considered in detail. The interpretative logic is simple but empirically supported by observations of these ratio values at different depositional environments in the Pacific: A1 is concentrated most highly in continental material while Fe and Mn are more concentrated in pelagic sediments. FeO/A12O3 can be used to differentiate between ophiolite associated chert and chert associated only with other sediments. TiO2/A12O3 is not a useful indicator, possibly because of the equalizing effect of widespread eolian transport. The A1/A1+Fe+Mn ratio was measured in detail in one stratigraphic section in central continental Greece. This ratio varied with the type of sediment admixture, decreasing in value after the influx of ophiolite debris-bearing sediments, even when their presence was undetectable in hand sample or under petrographic microscope.To help clarify the paleogeography of the main study area, the Pindos Zone, and to identify sources and dispersal patterns of extra-basinal materials, isopach maps of sedimentary facies of the Pindos were constructed. Superimposed directly upon the series of imbricated thrust slices that comprise the Pindos Zone, the maps are at best compressed pictures of the Pindos Sea Floor. Persistent regional variation of facies thicknesses over time suggests the existence of several smaller depressions surrounded by submarine highs in the Pindos Basin. 相似文献
79.
Effects of phenology and meteorological disturbance on litter rainfall interception for a Pinus elliottii stand in the Southeastern United States 总被引:1,自引:0,他引:1 下载免费PDF全文
John T. Van Stan II Miriam Coenders‐Gerrits Michael Dibble Philine Bogeholz Zachary Norman 《水文研究》2017,31(21):3719-3728
Litter layers develop across a diverse array of vegetated ecosystems and undergo significant temporal compositional changes due to canopy phenological phases and disturbances. Past research on temporal dynamics of litter interception has focused primarily on litter thickness and leaf fall, yet forest phenophases can change many more litter attributes (e.g., woody debris, bark shedding, and release of reproductive materials). In this study, weekly changes in litter composition over 1 year were used to estimate litter water storage dynamics and model event‐based litter interception. Litter interception substantially reduced throughfall (6–43%), and litter water storage capacity ranged from 1 to 3 mm, peaking when megastrobili release and liana leaf senescence occurred simultaneously during fall 2015. Tropical storm disturbances occurred during the sampling period, allowing evaluation of how meteorological disturbances altered litter interception. High wind speeds and intense rainfall from 2 tropical storms increased litter interception by introducing new woody debris, which, in this study, stored more water than the pre‐existing woody debris. After 2 extreme weather events, a third (Hurricane Hermine) did not increase woody debris (or litter interception), suggesting that the canopy pool of branches susceptible to breakage had been largely depleted. Needle and bark shedding had minor effects on litter interception. Results suggest that the release of reproductive materials and meteorological disturbances appear to be the major compositional drivers of litter interception beyond their obvious contribution to litter thickness. 相似文献
80.
Andrew D. Parsekian Benjamin M. Jones Miriam Jones Guido Grosse Katey M. Walter Anthony Lee Slater 《地球表面变化过程与地形》2011,36(14):1889-1897
Investigations on the northern Seward Peninsula in Alaska identified zones of recent (<50 years) permafrost collapse that led to the formation of floating vegetation mats along thermokarst lake margins. The occurrence of floating vegetation mat features indicates rapid degradation of near‐surface permafrost and lake expansion. This paper reports on the recent expansion of these collapse features and their geometry is determined using geophysical and remote sensing measurements. The vegetation mats were observed to have an average thickness of 0.57 m and petrophysical modeling indicated that gas content of 1.5–5% enabled floatation above the lake surface. Furthermore, geophysical investigation provides evidence that the mats form by thaw and subsidence of the underlying permafrost rather than terrestrialization. The temperature of the water below a vegetation mat was observed to remain above freezing late in the winter. Analysis of satellite and aerial imagery indicates that these features have expanded at maximum rates of 1–2 m yr‐1 over a 56 year period. Including the spatial coverage of floating ‘thermokarst mats’ increases estimates of lake area by as much as 4% in some lakes. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献