从局部地震临近预报到自然时间预报：一种简单的自助（DIY）方法
From Local Earthquake Nowcasting to Natural Time Forecasting: A Simple Do-It-Yourself (DIY) Method
AI总结：
本文提出一种基于古登堡-里克特关系和ROC曲线的自然时间地震预报方法，无需概率模型，通过计算阳性预测值来估计大地震概率，并在洛杉矶地区北岭地震后进行了验证。
摘要：
先前的论文概述了仅使用观测地震目录来追踪地震危险当前状态的临近预报方法。其中一种方法——“计数法”的基础是古登堡-里克特（GR）震级-频度关系。GR关系指出，对于每一个震级大于MT的大地震，平均有NGR个震级为MS的小地震。在本文中，我们利用这一基本关系，结合机器学习中的受试者工作特征（ROC）形式体系，来计算大地震的概率。该概率以自上次大地震以来发生的小地震数量n(t)为条件。我们在自然时间中工作，自然时间定义为大地震之间小地震的计数。我们不需要假设概率模型，这是一个主要优势。相反，概率是作为与ROC曲线相关的阳性预测值（PPV）来计算的。我们发现，在最近一次大地震之后，随着更多小地震的发生，PPV最初会下降，这表明了所观测到的大地震的时间聚集特性。随着小地震数量的持续累积，PPV随后开始上升。最终达到一个点，超过该点后，增长率变得更大且更为显著。在这里，我们通过将该方法应用于1994年1月17日加州洛杉矶附近发生的M6.7级北岭地震之后的局部区域，来对其进行描述和说明。
英文摘要：
Previous papers have outlined nowcasting methods to track the current state of earthquake hazard using only observed seismic catalogs. The basis for one of these methods, the "counting method", is the Gutenberg-Richter (GR) magnitude-frequency relation. The GR relation states that for every large earthquake of magnitude greater than MT , there are on average NGR small earthquakes of magnitude MS. In this paper we use this basic relation, combined with the Receiver Operating Characteristic (ROC) formalism from machine learning, to compute the probability of a large earthquake. The probability is conditioned on the number of small earthquakes n(t) that have occurred since the last large earthquake. We work in natural time, which is defined as the count of small earthquakes between large earthquakes. We do not need to assume a probability model, which is a major advantage. Instead, the probability is computed as the Positive Predictive Value (PPV) associated with the ROC curve. We find that the PPV following the last large earthquake initially decreases as more small earthquakes occur, indicating the property of temporal clustering of large earthquakes as is observed. As the number of small earthquakes continues to accumulate, the PPV subsequently begins to increase. Eventually a point is reached beyond which the rate of increase becomes much larger and more dramatic. Here we describe and illustrate the method by applying it to a local region around Los Angeles, California, following the January 17, 1994 magnitude M6.7 Northridge earthquake.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
