译文－华盛顿州Jones Creek（琼斯溪谷）泥石流灾害及其风险评价(二)

5 讨论

       运用F/N曲线进行定量的风险提供了一种可对比的可重复的泥石流风险分析方法，从而为生命和财产免受泥石流灾害冲击的保护措施提供客观决策。实际上，公众心理承受能力和环境能够影响F/N风险分析结果的解释。

美国政府对于2001年9月恐怖袭击的反应就是一个重要的事例，在此次事件中纽约市世贸中心双塔的倒塌导致3000人丧生。

过去的500年中美国本土死于恐怖活动的人数大约为3200，每年6.4人。2亿6千万美国公民现在生活在美国本土，美国个人在恐怖活动中的年死亡概率为2.5×10-8，与之相比Jones Creek冲积扇个人死亡概率为1.4×10-2。美国恐怖袭击的死亡危险能够归为可接受的风险，如果应用于某一产业或基础设施的所有者，很可能做出决策，灾害不能够辩解基金的花费。这个结果与最近开始的通过本土防卫计划(Homeland Defense)对美国国内外的恐怖袭击作斗争花费的数十亿美元形成鲜明对比。这个例子证实了即使F/N曲线作为风险的客观衡量标准并支撑对于灾害反应的决策，政治考虑和大众的心理承受能力能够压倒的客观性。

6 结论

       本文对Jones Creek冲击扇上的泥石流灾害及其风险进行了定量研究。通过测定有机质年龄和外推冲积扇上的泥石流沉积物厚度确定了重现期为500年的泥石流频率和规模。通过与泥石流体积建立相关关系确定了峰值流量。估算出设计泥石流的方量为90000 m3，相应峰值流量为320 m3/s。接下来的泥石流建模工作，绘制年死亡概率和期望死亡人数关系曲线定量化灾害的风险。F/N曲线表明现在存在的风险为现今西方社会所不能承受，并且应采取减灾措施。尽管F/N曲线可用于客观地评价风险是否值得花费基金，公众心理或是政治环境能够取代可接受的风险的概念。

       尽管受到探槽的数量和深度以及放射性碳测年的限制，本研究证实了本次研究努力和方法能够适用于评价由泥石流形成的冲积扇的灾害及其风险。考虑到山区存在大量的有相似人口的冲积扇和泥石流可预报性差(与洪灾相对)，灾害及其风险定量化和制图的统一体系迫在眉睫。希望本文能够为此目标稍尽绵薄之力。

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