Snow-avalanche and debris-flow hazards in the fjords of north-western Iceland,mitigation and prevention     

Armelle Decaulne 《Natural Hazards》2007,41(1):81-98

In the fjords of north-western Iceland, snow-avalanche and debris-flow hazards threaten 65% of the inhabitants. In this area, both historical and geomorphological evidences clearly demonstrate the recurrent danger from the steep slopes. Hazard vulnerability has increased during the last century, in connection with the population development of the Westfjords. Two snow-avalanche disasters during 1995 (in which 34 people were killed in two villages) prompted efforts to both mitigate and prevent future snow-avalanche and debris-flow activity. Research (qualitative and quantitative) on process characteristics describes prone terrain, runout distance, process behaviour along the slope, morphometric properties of the deposits and triggering factors. Acceptable risk, hazard and risk zoning are clearly defined by official regulations. Evacuation plans are determined from statistical characterisation of the risk and dynamic numerical modelling. To enhance the risk reduction, permanent and temporary measures aim to control the processes and to protect the population.  相似文献   

A Wind-Tunnel Simulation of Plume Dispersion Within a Large Array of Obstacles   总被引：2，自引：1，他引：1  

R.?M.?GailisEmail author  A.?Hill 《Boundary-Layer Meteorology》2006,119(2):289-338

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西准噶尔晚泥盆世碱性玄武岩的地球化学特征及其与塔里木大火成岩省岩浆岩对比          下载免费PDF全文

杨高学李永军  佟丽莉李甘雨 沈 锐 《地质科学》2017,(1):285-300

西准噶尔是近年来中亚造山带的研究热点地区之一,发育多条蛇绿混杂岩带。随着研究的深入,蛇绿岩混杂岩带中不断有碱性洋岛玄武岩被识别出来。本文对克拉玛依及达尔布特蛇绿混杂岩中的晚泥盆世枕状玄武岩进行详细的岩石地球化学及Sr?Nd同位素组成研究。结果表明西准噶尔晚泥盆世枕状玄武岩属于碱性玄武岩系列,岩石具有高TiO₂ （2.3%～3.8%）及P₂O₅ （0.38%～0.91%）,低MgO （2.41%～4.97%）,轻、重稀土元素分异较为明显,(La/Yb)_N = 5.1～14.5,无明显Eu异常（Eu/Eu* = 0.96～1.1）,相对富集Rb、Th、U,亏损Ba、K、Sr,没有明显Nb、Ta负异常,这些地球化学特征与洋岛玄武岩（OIB）极其相似。克拉玛依及达尔布特蛇绿混杂岩中枕状玄武岩具正ε_Nd(t)值（3.3～4.4）及年轻的模式年龄（0.83～0.72 Ga）,表明其来源于亏损地幔源区,通过同位素及微量元素研究认为源区可能为富辉石的橄榄岩,或不含橄榄石的辉石岩和角闪石岩,克拉玛依及达尔布特蛇绿混杂岩中的晚泥盆世枕状玄武岩形成于大洋板内与地幔柱有关的海山/大洋岛屿环境。这些明显不同于大陆板内具有富集特征的塔里木大火成岩省,它们分别属于两个明显不同的同位素地球化学省,即以富集型地幔为同位素组成的南部省及以亏损型地幔为同位素组成的北部省。  相似文献