A Spatiotemporal Clustering Model for the Third Uniform California Earthquake Rupture Forecast (UCERF3-ETAS): Toward an Operational Earthquake Forecast
A Spatiotemporal Clustering Model for the Third Uniform California Earthquake Rupture Forecast (UCERF3-ETAS): Toward an Operational Earthquake Forecast
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DOI：
10.1785/0120160173
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发表时间：
2017-06-01
影响因子：
3
通讯作者：
Werner, Maximilian J.
中科院分区：
文献类型：
--
作者：
Field, Edward H.;Milner, Kevin R.;Werner, Maximilian J.
我们，正在进行的加州地震概率工作组，提出了第三次统一加州地震破裂预报（UCERF 3）的时空聚类模型，其目标是代表余震，诱发地震活动，以及其他触发事件作为业务地震预报（OEF）的潜在基础。具体来说，我们增加了一个地震型余震序列（ETAS）的组成部分，以前公布的时间无关和长期的时间依赖的预测。这种组合模型，被称为UCERF 3-ETAS，共同代表了一个放松的分割假设，包括多故障断裂，弹性反弹模型故障为基础的断裂，和一个国家的最先进的时空聚类组件。它还代表了一种尝试，合并故障为基础的预测与统计地震学模型，这样的信息故障的接近，活动率，并考虑在OEF的时间，因为最后一次事件。我们描述了遇到的几个意想不到的挑战，包括需要弹性反弹和故障的特征幅度-频率分布（MFD），这两者都需要得到现实的触发行为。UCERF 3-ETAS生成M >= 2：5事件的合成目录，以输入到模型的任何先前M >= 2：5事件为条件。我们评估的结果与长期（1000年）的模拟，以及10年的时间段后，各种假设的情景主震。虽然结果是非常合理的，他们并不总是与简单的概念，即触发概率应该更大，如果主震位于断层附近一致。重要的因素包括断层附近的MFD是否包括显著的特征地震分量，以及大的触发事件是否可以从主震的破裂带内成核。由于UCERF 3-ETAS有许多不确定性来源，任何后续版本或竞争模型也是如此，因此需要在实际应用的背景下考虑潜在的有用性。
We, the ongoing Working Group on California Earthquake Probabilities, present a spatiotemporal clustering model for the Third Uniform California Earthquake Rupture Forecast (UCERF3), with the goal being to represent aftershocks, induced seismicity, and otherwise triggered events as a potential basis for operational earthquake forecasting (OEF). Specifically, we add an epidemic-type aftershock sequence (ETAS) component to the previously published time-independent and long-term time-dependent forecasts. This combined model, referred to as UCERF3-ETAS, collectively represents a relaxation of segmentation assumptions, the inclusion of multifault ruptures, an elastic-rebound model for fault-based ruptures, and a state-of- the-art spatiotemporal clustering component. It also represents an attempt to merge fault-based forecasts with statistical seismology models, such that information on fault proximity, activity rate, and time since last event are considered in OEF. We describe several unanticipated challenges that were encountered, including a need for elastic rebound and characteristic magnitude-frequency distributions (MFDs) on faults, both of which are required to get realistic triggering behavior. UCERF3-ETAS produces synthetic catalogs of M >= 2: 5 events, conditioned on any prior M >= 2: 5 events that are input to the model. We evaluate results with respect to both long-term (1000 year) simulations as well as for 10-year time periods following a variety of hypothetical scenario mainshocks. Although the results are very plausible, they are not always consistent with the simple notion that triggering probabilities should be greater if a mainshock is located near a fault. Important factors include whether the MFD near faults includes a significant characteristic earthquake component, as well as whether large triggered events can nucleate from within the rupture zone of the mainshock. Because UCERF3-ETAS has many sources of uncertainty, as will any subsequent version or competing model, potential usefulness needs to be considered in the context of actual applications.