The aim of this work is the evaluation of the vulnerability of landslides in static, pseudostatic and dynamic conditions, to produce slope instability maps. A deterministic approach, using a GIS, (ILWIS 1.4 — The Integrated Land and Water Information System User's Manual, Enschede, 1993, The Netherlands) is presented. The analysis in static and pseudostatic conditions, using the infinite slope: analysis and the ordinary slice method, is carried out and the values of Fs (factor of safety) and Kc (coefficient of critical horizontal acceleration) are evaluated; the analysis in dynamic condition is performed, using Newmark's method, (Geotechnique, 1965, 23, 139-60), and the value of the final displacement during the application of an accelerogram is calculated. The applied methodologies and the results for the area corresponding to the NE sector of the 1:50.000 “Fabriano” (Marche Region, Italy) geological map sheet, are presented. 相似文献
On rimmed shelves of Bahamian-type, characterized by chlorozoan associations and typical of tropical seas, carbonate production keeps pace with normal sea-level rise except when rapid rise or drastic environmental changes occurs. On the other hand, open temperate carbonate shelves are characterized by low carbonate production of the foramol association (molluscs, benthic foraminifera, bryozoans, coralline algae, etc.) and generally show seaward relict sediments, because carbonate production cannot keep pace with normal rate of sea-level change.
Several examples of recent drowning foramol carbonate platforms (e.g., large areas of the Mediterranean Sea, eastern-northeastern Yucatan Shelf) as well as analogous ancient drowned foramol-type carbonate platforms (e.g., early to middle Miocene of the Southern Apennines; Miami Terrace) may support the idea that the drowning of many ancient carbonate platforms has been favoured by their biogenic (foramol sensu lato) constitution. Because of their typically low rate of growth, foramol carbonate platforms are fated to be drowned even if the sea-level rise is one with which the normal growth of chlorozoan platforms can keep pace. Similar conditions may also occur in tropical areas where variations in environmental conditions, such as the presence of cold waters, changes in salinity and increased nutrients, preclude the development of chlorozoan associations. 相似文献
Very few data on Early Triassic marine ostracods are available. In most of cases, the data concern the upper part of the Early Triassic. The Çürük da? section, located in the Western Taurides (Turkey), well stratigraphically constrained by conodonts and foraminifera, has been re-sampled for ostracod study. A significant fauna has been discovered in the Late Permian and the levels of the Earliest Triassic (Hindeodus parvus and Isarcicella isarcica staeschei zones). The ostracods of the basis of the Kokarkuyu Fm. are the oldest Triassic forms ever discovered. The occurrence of Palaeocopes in the earliest Triassic and similarity between the Permian and Induan assemblages suggest that the Lower Triassic Çürük da? ostracods represent a survival assemblage after the Permo-Triassic mass-extinction. To cite this article: S. Crasquin-Soleau et al., C. R. Geoscience 334 (2002) 489–495.相似文献
Modeling and forecasting damage from wind storms is a major issue for insurance companies. In this article, we focus on the sensitivity of estimations of return periods for extreme events with respect to modeling assumptions and the type of input data. Numerous variables play a role: the quality of data concerning the location of insured buildings and weather report homogeneity, missing updates for correcting non-stationarities concerning the insurance portfolio history, ground roughness or climate change, the evolution of the model after an unprecedented event such as the Lothar storm observed in 1999 in Europe, temporal aggregation of daily events over several days, where events could span over several days up to one week, and storm trajectories, which could change due to global warming or sweep larger areas. Our work explores three important aspects. First, we highlight the geographic heterogeneity of the spatial distribution of wind speeds and the resulting damages. Therefore, we propose to partition the French territory into 6 relatively homogeneous storm zones, based on the dependence among observed wind speeds and geographic distance. Second, we extend a storm index—defined in Mornet et al. (Risk Anal 35:2029–2056, 2015)—to take into account geographic heterogeneity, and we analyze its tail behavior to show the difficulties met to obtain reliable results on extreme events. Third, we explore the calculation of Solvency Capital Requirements based on a model that we propose for the annual claim amount distribution. The purpose of our analysis is to quantify and to point out the high level of uncertainty in the computation of return periods and of other quantities strongly influenced by extreme events. 相似文献
Octopuses are active predators that feed on a wide range of prey including crustaceans, fishes, and mollusks. They are important components of coral reef systems and support local and artisanal fisheries in the Gulf of México. Octopus insularis has been found to be one of the most relevant components in catches from the coral reef system of Veracruz in the southwestern Gulf of Mexico, and its role in the ecosystem requires assessment. To corroborate the morphological identification of O. insularis, six octopuses were identified by genetic methods. And to understand the trophic relationships between this octopus species and its prey, 394 octopuses caught during 2016 and 2017 by an artisanal fleet were sampled and their stomach contents analyzed. Results showed that crustaceans are the most frequently consumed group, with the genera Mithraculus and Etisus being the most important in the diet. Fishes, bivalves, and gastropods were identified as uncommon prey items in the diet. Their presence in the stomachs could be related to the movement of this octopus outside of the coral reef. Considering that our samples were of medium‐ and large‐sized individuals, cannibalism could be discarded for O. insularis in this size range in the Veracruz reef system. These findings suggest a generalist and opportunistic predation of O. insularis on the most abundant and available prey in the study area, namely the crustaceans. These represents an effective transfer of biomass from the low trophic levels to top predators in the coral reef system. 相似文献
The Large Marine Ecosystem (LME) concept is widely established as a large-scale approach to coastal and marine management. LME-oriented activities have focused mainly on natural sciences. Socioeconomic and governance aspects have only recently been receiving increased attention. The 64 LMEs that have been defined appeared to exhibit considerable diversity in characteristics that would be expected to affect governability. This paper explores two questions: (1) Do the LMEs vary widely enough in geopolitical complexity that different approaches to governance may be required for different LMEs? (2) Are there groups of LMEs within which one might take similar approaches to governance? The analysis demonstrates that there is considerable heterogeneity among LMEs with regard to characteristics that would be expected to affect governability. It concludes that a diversity of governance approaches will be required to cope with this heterogeneity. It also appears that LMEs can be grouped according to these characteristics. This suggests that different approaches could be considered for clusters rather than for individual LMEs and that there can be sharing of experience and learning within clusters. The types of relationships between features of LMEs and the ‘best’ approaches to marine governance are discussed in the context of emerging governance ideas. 相似文献
This paper describes a simple and adaptive methodology for large area forest/non-forest mapping using Landsat ETM+ imagery and CORINE Land Cover 2000. The methodology is based on scene-by-scene analysis and supervised classification. The fully automated processing chain consists of several phases, including image segmentation, clustering, adaptive spectral representativity analysis, training data extraction and nearest-neighbour classification. This method was used to produce a European forest/non-forest map through the processing of 415 Landsat ETM+ scenes. The resulting forest/non-forest map was validated with three independent data sets. The results show that the map’s overall point-level agreement with our validation data generally exceeds 80%, and approaches 90% in central European conditions. Comparison with country-level forest area statistics shows that in most cases the difference between the forest proportion of the derived map and that computed from the published forest area statistics is below 5%. 相似文献
Igneous garnets have the potential to strongly fractionate rare earth elements (REE). Yet informations on partition coefficients
are very scant, and criteria for distinguishing between hydrothermal and magmatic garnets are ambiguous. To fill this gap,
we present trace element and isotopic data for two types of Ca-rich garnets from phonolites (Mt. Somma-Vesuvius). Both Ca-garnet
populations are different in their style and dynamics of fractionation: one population is progressively strongly depleted
in HREE from core to rim, reflecting REE fractionation in the host phonolite via earlier-crystallized garnets. Such examples
for extreme changes in HREE in garnets are only known for hydrothermal grandites by REE-bearing fluids. The second garnet
population is homogeneous and formed in a closed system. Near-flat patterns between Sm and Lu confirm experimental data indicating
lower D(Sm)/D(Lu) for Ca-rich garnets than for e.g. pyrope-rich garnets. It follows: DGrt/PhMelt for La = 0.5, Sm = 48 and Yb = 110. 相似文献