Long-Term Time-Dependent Probabilities for the Third Uniform California Earthquake Rupture Forecast (UCERF3)
Long-Term Time-Dependent Probabilities for the Third Uniform California Earthquake Rupture Forecast (UCERF3)
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DOI：
10.1785/0120140093
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发表时间：
2015-04-01
影响因子：
3
通讯作者：
Zeng, Yuehua
中科院分区：
文献类型：
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作者：
Field, Edward H.;Biasi, Glenn P.;Zeng, Yuehua
2014年加州地震概率工作组（WGCEP 2014）为第三次统一加州地震破裂预报（UCERF 3）提供了随时间变化的地震概率。建立在UCERF3的时间无关的模型先前公布的，更新模型被用来表示弹性反弹隐含的概率。一种新的方法已经开发，解决了适用性问题，在以前的方法为未分割的模型。新的方法还支持幅度相关的非周期性和帐户的历史开放间隔故障，缺乏一个日期的最后一个事件的约束。认知的不确定性表示与逻辑树，产生5760个不同的预测。各种评估指标的结果，包括逻辑树的敏感性分析和比较以前的模型（UCERF2）。对于30年M >= 6.7的概率，UCERF2最显著的变化是卡拉维拉斯断层增加了三倍，圣哈辛托断层减少了三倍。这种变化主要是由于与时间无关的模型的差异（例如，断层滑动率），放松分割和包含多断层破裂是特别有影响力的。事实上，考虑到该研究中的分割假设，一些UCERF 2断层太长，无法产生M 6.7大小的事件。概率模型差异也有影响，UCERF3中的隐含收益（相对于泊松模型）通常较高。考虑到历史上的开放间隔是一个原因。另一个是总弹性反弹模型重量有效增加27%。影响UCERF2和UCERF3之间差异的确切因素，以及逻辑树分支的相对重要性，在整个地区都有所不同，并取决于感兴趣的评估指标。例如，M >= 6.7的概率可能不是其他危险或损失度量的良好替代。这种敏感性，再加上模型的近似性质和已知的局限性，意味着UCERF 3的适用性应根据具体情况进行评估。
The 2014 Working Group on California Earthquake Probabilities (WGCEP 2014) presents time-dependent earthquake probabilities for the third Uniform California Earthquake Rupture Forecast (UCERF3). Building on the UCERF3 time-independent model published previously, renewal models are utilized to represent elastic-rebound-implied probabilities. A new methodology has been developed that solves applicability issues in the previous approach for unsegmented models. The new methodology also supports magnitude-dependent aperiodicity and accounts for the historic open interval on faults that lack a date-of-last-event constraint. Epistemic uncertainties are represented with a logic tree, producing 5760 different forecasts. Results for a variety of evaluation metrics are presented, including logic-tree sensitivity analyses and comparisons to the previous model (UCERF2). For 30 yr M >= 6.7 probabilities, the most significant changes from UCERF2 are a threefold increase on the Calaveras fault and a threefold decrease on the San Jacinto fault. Such changes are due mostly to differences in the time-independent models (e.g., fault-slip rates), with relaxation of segmentation and inclusion of multifault ruptures being particularly influential. In fact, some UCERF2 faults were simply too long to produce M 6.7 size events given the segmentation assumptions in that study. Probability model differences are also influential, with the implied gains (relative to a Poisson model) being generally higher in UCERF3. Accounting for the historic open interval is one reason. Another is an effective 27% increase in the total elastic-rebound-model weight. The exact factors influencing differences between UCERF2 and UCERF3, as well as the relative importance of logic-tree branches, vary throughout the region and depend on the evaluation metric of interest. For example, M >= 6.7 probabilities may not be a good proxy for other hazard or loss measures. This sensitivity, coupled with the approximate nature of the model and known limitations, means the applicability of UCERF3 should be evaluated on a case-by-case basis.