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241.
Despite the long tradition of technical mitigation on a catchment scale in European mountain regions, losses due to mountain
hazards are still considerably high in number and monetary loss. Therefore, the concept of technical mitigation had been supplemented
by land-use planning and, more recently, local structural protection. Local structural protection includes measures directly
implemented at or adjacent to endangered objects, and has proven to be particularly cost-effective with respect to integral
risk management strategies. However, the effect of local structural protection in reducing the vulnerability of elements at
risk, and the associated consequences with respect to a reduction of structural vulnerability have not been quantified so
far. Moreover, there is a particular gap in quantifying the expenditures necessary for local structural protection measures.
Therefore, a prototype of residential building adapted to mountain hazards is presented in this study. This prototype is equipped
with various constructional elements to resist the incurring impact forces, i.e., of fluvial sediment transport and of snow
avalanches. According to possible design loads emerging from these hazard processes, the constructive design necessary is
presented, and the amount of additional costs required for such an adaptation is presented. By comparing these costs with
quantitative loss data it is shown that adapted building design is particularly effective to reduce the consequences of low-magnitude,
high-frequency events in mountain regions. 相似文献
242.
Hydrothermal precipitates associated with bimodal volcanism in the Central Bransfield Strait,Antarctica 总被引:1,自引:0,他引:1
Sven?PetersenEmail author Peter?M.?Herzig Ulrich?Schwarz-Schampera Mark?D.?Hannington Ian?R.?Jonasson 《Mineralium Deposita》2004,39(3):358-379
Polymetallic sulfide-sulfate mineralization enriched in Pb-Ag-As-Sb-Hg occurs in the Bransfield Strait, a late Tertiary-Quaternary marginal basin close to the Antarctic Peninsula. The mineralization is associated with bimodal volcanism and pelagic and volcaniclastic sediment in rifted continental crust. Hydrothermal precipitates have been recovered from two shallow (1,050–1,000 m water depth) submarine volcanoes (Hook Ridge and Three Sisters) in the Central Bransfield Strait. Mineralization at Hook Ridge consists of polymetallic sulfides, massive barite, and pyrite and marcasite crusts in semilithified pelagic and volcaniclastic sediment. Native sulfur commonly infills void space and cements the volcaniclastic sediment. The polymetallic sulfides are dominated by sphalerite with minor galena, enargite, tetrahedrite-tennantite, pyrite, chalcopyrite, and traces of orpiment cemented by barite and opal-A. The presence of enargite at Hook Ridge, the abundance of native sulfur, and the low Fe content of sphalerite indicate a high sulfur activity of the hydrothermal fluids responsible for mineralization. The sulfur isotopic composition of Hook Ridge precipitates documents the complexity of the sulfur sources in this hydrothermal system with variable influence of biological activity and possibly magmatic contributions. Homogenization temperatures and salinities of fluid inclusions in barite and opal-A suggest that boiling may have affected the hydrothermal fluids during their ascent. The discovery of massive barite-silica precipitates at another shallow marine volcano (Three Sisters volcano) attests to the potential for hydrothermal mineralization at other volcanic edifices in the area. The characteristics of the mineralization in the Bransfield Strait with rifting of continental crust, the presence of bimodal volcanism, including highly evolved felsic volcanic rocks, the association with sediments, and the Pb-Ag-As-Sb-Hg enrichment are similar to the setting of massive sulfide deposits in the Okinawa Trough, and distinct from those of sediment-dominated hydrothermal systems such as Escanaba Trough, Middle Valley, and Guaymas Basin. The geological setting of the Bransfield Strait is also broadly similar to that of some of the largest volcanogenic massive sulfide deposits in the ancient record, such as the Iberian Pyrite Belt.Editorial handling: B. Lehmann 相似文献