Interpretation of probability of landsliding triggered by rainfall     

Chit?Ko Ko  Phil?FlentjeEmail author  Robin?Chowdhury 《Landslides》2004,1(4):263-275

This paper is a contribution to an important aspect of the systematic and quantitative assessment of landslide hazard and risk. The focus is on site-specific and detailed assessment for rainfall-triggered landslides and, in particular, on the estimation and interpretation of the temporal probability of landsliding. Historical rainfall data over a 109-year period were analysed with particular reference to a site along the Unanderra and Moss Vale Railway Line in the State of New South Wales, Australia. It is shown that the recurrence interval of landsliding and hence annual probability of occurrence is subject to significant uncertainty and that it cannot be regarded as a constant. Accordingly landslide hazard varies spatially as well as being a function of time. For the example case study considered in this paper the annual probability of landslide occurrence was estimated to be in the range 0.026–0.172. However, the mean annual probability of landslide reactivation was estimated to be in the range 0.037–0.078. Utilisation of methods for probability assessment proposed in this paper will contribute to more realistic assessment of hazard and risk and, therefore, to more efficient risk management.  相似文献   

Mafic pyroclastic flows at Santa Maria (Gaua) Volcano, Vanuatu: the caldera formation problem in mainly mafic island arc volcanoes     

Claude Robin  Jean-Philippe Eissen  Michel Monzier 《地学学报》1995,7(4):436-443

At Santa Maria Volcano (New Hebrides island arc), extensive ash and scoria flow deposits overlie the mainly effusive, pre-caldera cone. Hydromagmatic features characterize these deposits, the composition of juvenile clasts ranges from basalt to acid andesite/dacite (SiO₂= 51–63.6%) with a dominant basaltic composition. The stratigraphic position of this pyroclastic series and its spatial distribution around a 8.5 km × 6 km wide caldera provide evidence of a relationship between this series and the caldera formation. In addition, these pyroclastic deposits are co-genetic to parasitic cones and lava flows developed along faults concentric to the caldera. Both series result from a compositionally layered magma reservoir, the subordinate differentiated magmas being the result of fractional crystallization from the basalts. A model of caldera formation which implies a large hydromagmatic eruption at the central vent and minor magma withdrawal by flank eruptions is proposed. This model emphasizes the importance of mafic hydroclastic eruptions in the caldera forming event and contradicts a model implying only quiet subsidence, a process often proposed for the formation of calderas in island are volcanoes of mainly mafic composition.  相似文献   

EEC fisheries: agreement at last     

Robin Churchill 《Marine Policy》1983,7(2):74

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200-mile limits: recent claims: A detailed annotated survey of the recent proliferation of claims to 200-mile fishing limits and economic zones.     

Robin Churchill. 《Marine Policy》1977,1(3):255-258

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Can the Einstein-de Sitter model adequately describe the Universe at any epoch?     

A. Gordon Emslie  Robin M. Green 《Astrophysics and Space Science》1978,58(1):181-188

The characteristics of Friedmann model universes containing decoupled matter and radiation are investigated to establish the range in redshift over which the frequently assumed Einstein-de Sitter approximation is valid. This approximation is found to have decidedly doubtful value for small, yet entirely plausible, values of the material density parameter.  相似文献   

Effect of the thermal gradient variation through geological time on basin modeling; a case study: The Paris basin     

L. Amir  L. Martinez  J.R. Disnar  J.-L. Vigneresse  R. Michels  F. Guillocheau  C. Robin 《Tectonophysics》2005,400(1-4):227-240

Many studies investigated the thermal modeling of the Paris basin for petroleum interests during the 1970s. Most of the softwares developed by oil companies or research centers were based on the assumption of a constant thermal gradient. In order to take into consideration the variation of the thermal gradient during basin evolution, we developed the TherMO's Visual Basic 1D program. We applied our model to twenty boreholes located along a cross-section roughly running EW over 150 km in the center of the Paris basin. The numerical results were calibrated with organic matter maturity data. TherMO's simulates the amount of heat provided to the sedimentary organic matter. The heat parameter simulated shows lateral variation along the cross-section. It decreases from Rambouillet to Trou Aux Loups boreholes (87–66 mW/m²) at about 100 km more to the east whereas the heat flux value simulated is 73 mW/m² in St. Loup borehole. The mean thermal gradient calculated for liassic horizons at 87 My for the Rambouillet well is 50.4 °C/km. This value is similar to previously published results. By integrating the calculation of the thermal gradients and conductivities related to the burial of each stratigraphic sequence, our approach points out variations in the thermal regimes the sedimentary organic matter (SOM) has been subjected to through geological time.  相似文献   

Alteration paragenesis and mineral chemistry of the Tjårrojåkka apatite–iron and Cu (-Au) occurrences, Kiruna area, northern Sweden     

Åsa Edfelt  Robin N. Armstrong  Martin Smith  Olof Martinsson 《Mineralium Deposita》2005,40(4):409-434

The northern Norrbotten area in northern Sweden, is an important mining district and hosts several deposits of Fe-oxide Cu-Au-type. One of the best examples of spatially, and possibly genetically, related apatite–iron and copper–gold deposits in the region is at Tjårrojåkka, 50 km WSW of Kiruna. The deposits are hosted by strongly sheared and metamorphosed intermediate volcanic rocks and dolerites and show a structural control. The Tjårrojåkka iron deposit is a typical apatite–iron ore of Kiruna-type and the Tjårrojåkka copper occurrence shows the same characteristics as most other epigenetic deposits in Norrbotten. The host rock has been affected by strong albite and K-feldspar alteration related to mineralisation, resulting in an enrichment of Na, K, and Ba. Fe and V were depleted in the altered zones and added in mineralised samples. REE were enriched in the system, with the greatest addition related to mineralisation. Y was also mobile associated with albite alteration and copper mineralisation. The Tjårrojåkka iron and copper deposits show comparable hydrothermal alteration minerals and paragenesis, which might be a product of common host rock and similarities in ore fluid composition, or overprinting by successive alteration stages. Mineralogy and mineral chemistry of the alteration minerals (apatite, scapolite, feldspars, amphiboles, and biotite) indicate a higher salinity and Ba/K ratio in the fluid related to the alterations in the apatite–iron occurrence than in the copper deposit, where the minerals are enriched in F and S. The presence of hematite, barite, and in SO₄ in scapolite suggests more oxidising-rich conditions during the emplacement of the Tjårrojåkka-Cu deposit. From existing data it might be suggested that one evolving system created the two occurrences, with the copper mineralisation representing a slightly later product.  相似文献   

Determination of fabric and strain ellipsoids from measured sectional ellipses—implementation and applications     

Patrick Launeau  Pierre-Yves F. Robin   《Journal of Structural Geology》2005,27(12):20

Geologists examine fabrics to constrain models of formation or of deformation of rocks, and it is often convenient to summarise the results by a fabric ellipsoid. As fabric data are commonly collected on planar sections through the rock, estimating a fabric ellipsoid from sectional ellipses, often with arbitrary orientations, is an important task. An algebraic method to calculate such an ellipsoid, presented in an earlier paper, has been implemented with the program ellipsoid. It is used here on examples that illustrate questions and issues that arise when collecting, selecting and processing sectional fabric data, and when assessing the results. The quality of fit of the ellipsoid to the data is assessed in all cases. Examples include a case in which the average sizes of markers on individual sections can be used in the determination of the ellipsoid, and other cases in which such sizes are not useful; a case in which sectional ellipses are not obtained from closed markers; and a case in which data scatter and insufficient coverage of section orientations lead to a hyperboloid instead of an ellipsoid.  相似文献   

A Holocene pollen and diatom record from Vanderlin Island, Gulf of Carpentaria, lowland tropical Australia   总被引：1，自引：0，他引：1  

Matiu Prebble  Robin Sim  Jan Finn  David Fink 《Quaternary Research》2005,64(3):357-371

Sedimentary, palynological and diatom data from a dunefield lake deposit in the interior of Vanderlin Island in the Gulf of Carpentaria are presented. Prior to the formation of present perennial lake conditions, the intensified Australian monsoon associated with the early Holocene marine transgression allowed Cyperaceae sedges to colonise the alluvial margins of an expansive salt flat surrounded by an open Eucalyptus woodland. As sea level stabilised between 7500 and 4500 cal yr B.P. coastal dunes ceased to develop allowing dense Melaleuca forest to establish in a Restionaceae swamp. Dune-sand input into the swamp was diminished further as the increasingly dense vegetation prevented fluvial and aeolian transported sand arriving from coastal sources. This same process impounded the drainage basin allowing a perennial lake to form between 5500 and 4000 cal yr B.P. Myriophyllum and other aquatic taxa colonised the lake periphery under the most extensive woodland recorded for the Holocene. The palynological data support an effective precipitation model proposed for northern Australia that suggests more variable conditions in the late Holocene. A more precise measure of effective precipitation change is provided by diatom-based inferences that indicate few changes in lake hydrology. Such interpretations are explained in terms of palynological sensitivity to adjustments in local fire regimes where regional precipitation change may only be recorded indirectly through fire promoting mechanisms, including intensified ENSO periodicity and human impact.  相似文献   

The Mesozoic ostracod genus Arculicythere Grékoff: further evidence for the southern Gondwana seaway     

Sara Ballent  Robin Whatley   《Cretaceous Research》2006,27(6):728-734

This paper demonstrates that Arculicythere Grékoff is a widespread taxon in the uppermost Upper Jurassic and Lower Cretaceous of Gondwana. It occurs in Madagascar, India, Israel, South Africa, the Falklands Plateau, Argentina and Australia. The earliest record is from the Upper Tithonian of Madagascar but the most profuse occurrences are in the Albian, when the genus was very widespread around Gondwana. Its distribution seems to be associated with a major southern Gondwana seaway, and the genus provides additional proof of the existence of this corridor. Unlike another endemic gondwanine genus, Majungaella Grékoff, which ranged from earlier in the Jurassic but extended into the Neogene in the Antarctic, or Rostrocytheridea Dingle that survived into the Campanian of the Antarctic, Arculicythere seems to have become extinct in the Albian.  相似文献