Objective assessment of source models for seismic hazard studies: with a worked example from UK data
Objective assessment of source models for seismic hazard studies: with a worked example from UK data
复制标题
地震灾害研究震源模型的客观评估：以英国数据为例
DOI：
10.1007/s10518-011-9299-6
复制
发表时间：
2012
影响因子：
4.6
通讯作者：
P. W. Winter
中科院分区：
文献类型：
--
作者：
R. Musson;P. W. Winter
到目前为止，提高概率地震灾害分析（PSHA）可靠性的研究主要集中在评估专家意见和主观判断的方法上。虽然在PSHA的某些领域，主观意见是不可避免的，但评估程序和审查方法可能会在已经得出的判断基础上作出进一步的主观判断。找到客观评估震源模型的技术是有帮助的，这些技术可以显示地震活动性方面的解释的物理意义。经验表明，善意但有缺陷的设计决策可能导致源模型与用作输入的地震历史不兼容。本文提出了一种生成符合历史地震目录完备性阈值的大量合成地震目录的方法。将研究区划分为均匀单元格，然后计算历史目录和模拟目录中每个单元格的地震次数。将历史模式与一组1,000个模拟模式进行比较，使用X2检验，表明历史模式是否可信地属于震源模型可获得的结果集的成员。第二种方法是根据星等频率绘制大量模拟星表样本的分布图，并观察历史星表是否在这个分布范围内，还是一个异常值。如果证明不可能使用该模型复制历史目录，它就会使人怀疑该模型是否有效地描述了控制未来灾害的地震活动率。至少，需要仔细调查这种差异，以确保模型没有错误。这里为英国提供了一个有效的例子，使用了全球地震危险图（GSHAP）中使用的源模型，与人为构建的可信但有缺陷的模型进行了比较。两次试验发现，GSHAP模型是英国地震活动性模式的一个可接受的表示，而人工模型最终被拒绝。
Up to now, the search for increased reliability in probabilistic seismic hazard analysis (PSHA) has concentrated on ways of assessing expert opinion and subjective judgement. Although in some areas of PSHA subjective opinion is unavoidable, there is a danger that assessment procedures and review methods contribute further subjective judgements on top of those already elicited. It is helpful to find techniques for objectively assessing seismic source models that show what the interpretations physically mean in terms of seismicity. Experience shows that well-meaning but flawed design decisions can lead to source models that are incompatible with the seismic history that was used as input. In this paper a method is demonstrated in which large numbers of synthetic earthquake catalogues, that match the completeness thresholds of the historical catalogue, are generated. The study area can be divided into a grid of uniform cells, and the number of earthquakes in each cell in both the historical catalogue and each simulated catalogue are then counted. Comparison of the historical pattern and a set of 1,000 simulated patterns, using a X2 test, shows if the historical pattern is credibly a member of the set of outcomes obtainable from the seismic source model. A second method is to chart the distribution of a large sample of simulated catalogues in terms of magnitude frequency, and observe whether the historical catalogue is comfortably within this distribution, or an outlier. If it proves impossible to replicate the historical catalogue using the model, it casts doubt on whether the model is a valid depiction of the seismicity rates that will govern the future hazard. At the very least, the disparity needs careful investigation to ensure the model is error-free. A worked example is presented here for the UK, using a source model that was used in Global Seismic Hazard Map (GSHAP), compared to one that was artificially constructed to be credible but flawed. Two tests find the GSHAP model to be an acceptable representation of the pattern of seismicity in the UK, while the artificial model is conclusively rejected.