Collaborative Research: From Earthquake Physics to Testable Forecasts

试图将地震物理学纳入其中的模型在地震学中发挥着越来越重要的作用，并在地震危险性评估中普遍存在。大多数情况下，告知这些模型的物理概念是基于专家意见的启发性动机。统一加州地震破裂预报（UCERF 2）采用了几个这样的模型。为了增加即将到来的UCERF 3的可测试性，我们建议研究特征地震假说，最大震级与断层长度的关系，以及库仑应力假说。对于许多断层，地震学家确定了所谓的特征地震，并将其作为灾害评估中的预期目标地震。最突出和最好的研究例子是在帕克菲尔德，加利福尼亚州的6级事件序列。研究表明，这一现象可能是由频率-震级分布的上震级范围的低样本量解释的。最大震级与断层长度的关系在灾害评估中起着重要作用，因为它被用来估计特定断层未来大事件的规模。这种关系纯粹是基于后验观察，并没有使用先验预测进行测试。所选模型中最复杂的是库仑应力模型。它表现出很强的描述能力，但也依赖于通过拟合自由参数的后验观测。它的不确定性范围仍然相对未被探索。所有这些概念模型的共同点是，它们的预测能力从来没有经过严格的测试，这在一定程度上是因为它们很难被表述为可测试的假设。我们建议探索这些假设的不确定性范围，并将其转化为可检验的假设，在地震可预报性研究合作实验室的框架内进行严格的检验。这项研究将为UCERF 3的工作增加更多的可测试性，并有助于理解和量化这些模型对地震危险性评估的影响。

Models that attempt to incorporate earthquake physics play an increasingly important role in seismology and are prevalent in seismic hazard assessment. Most often, the physical ideas that inform these models are heuristically motivated and based on expert opinion. The Uniform California Earthquake Rupture Forecast (UCERF2) employs several such models. To increase the testability of the upcoming UCERF3, we propose to investigate the characteristic earthquake hypothesis, the relation of maximum magnitude to fault length, and the Coulomb Stress hypothesis. For many faults, seismologists identified so-called characteristic earthquakes and include them as expected target earthquakes in hazard assessment. The most prominent and best studied example is the sequence of magnitude 6 events at Parkfield, CA. Studies have shown that this phenomenon possibly could be explained by low sample size from the upper magnitude ranges of the frequency-magnitude distribution. The relation of maximum magnitude to fault length plays a major role in hazard assessment as it is used to estimate the size of future large events at particular faults. This relation is based purely on a posteriori observations and has not been tested using a priori predictions. The most complicated of the selected models is the Coulomb Stress model. It shows great descriptive capabilities but is also relies on a posteriori observations through fitting of the free parameters. Its uncertainty range remains relatively unexplored. Common to all of these conceptual models is the fact that they were never rigorously tested for their predictive power, owing in some part to the difficulty in formulating them as testable hypotheses. We propose to explore the uncertainty ranges of these hypotheses and to translate them into testable hypotheses to be tested rigorously in the framework of the Collaboratory for the Study of Earthquake Predictability. This study will add more testability to the UCERF3 effort and help to understand and to quantify the impact of these models on seismic hazard assessment.