The magnitude (M_W) 5.5 Pohang, Korea, earthquake on 15 November 2017, induced by the Pohang Engineered Geothermal Systems (EGS) project, caused one fatality and ∼US$300 million of economic consequences. The Commission, appointed by the Korean Government to investigate this earthquake, has made public a release of data including magnitudes of the smaller earthquakes associated with the well stimulations. On the basis of this earthquake population, it has been proposed that a significant probability of such losses was predictable beforehand, and that the project should have been suspended, implying that its developer was remiss for not doing so. This argument depends on the low b-value estimated, ∼0.61. However, three factors are shown to contribute, individually or in combination, to inaccuracy of these magnitude determinations: the low recording bandwidth of the permanent seismograph stations in the area; miscalibration of the formula for determining local magnitudes in Korea; and the relation used to estimate magnitudes of smaller events from larger events by template matching. These factors all cause underestimation of magnitudes of the smallest events documented, resulting in underestimation of b-values. The true b-values are higher, being 1.12 for the earthquakes associated with the August 2017 stimulation of well PX-1; similar values are estimated for the other well stimulations. A consequence of this analysis is that the probability of any earthquake as large as M_W = 5.5, predicted ahead of its occurrence by extrapolation using b-values, was much lower than has been claimed. This analysis highlights the need for agreed workflow specifications for reporting datasets like this, where the data might influence prosecution of EGS developers, as well as agreed specifications for acceptable economic risk arising from EGS projects.

大小（_兆瓦）5.5韩国浦项地震工程，是由浦项工程地热系统（EGS）项目引发的2017年11月15日地震，造成1人死亡，约3亿美元的经济后果。由韩国政府任命的负责调查此次地震的委员会已公开发布数据，其中包括与增产井相关的小地震的规模。根据这些地震的人口，有人建议事先可以预测这种损失的可能性很大，因此该项目应该被暂停，这意味着其开发商因不这样做而被辞职。该论点取决于估计的低b值〜0.61。但是，显示了三个因素（单独或组合）有助于这些幅度确定的不准确性：该地区永久地震台站的记录带宽低；确定韩国当地大小的公式的校准不当；以及用于通过模板匹配从较大事件中估计较小事件的大小的关系。这些因素都会导致对记录的最小事件的大小的低估，从而导致b值的低估。真实的b值更高，与2017年8月PX-1井增产相关的地震为1.12; 对于其他油井增产措施，估计相似的值。该分析的结果是，任何地震的概率都可能高达M 以及用于通过模板匹配从较大事件中估计较小事件的大小的关系。这些因素都会导致对记录的最小事件的大小的低估，从而导致b值的低估。真实的b值更高，与2017年8月PX-1井增产相关的地震为1.12; 对于其他油井增产措施，估计相似的值。该分析的结果是，任何地震的概率都可能高达M 以及用于通过模板匹配从较大事件中估计较小事件的大小的关系。这些因素都会导致对记录的最小事件的大小的低估，从而导致b值的低估。真正的b值较高，与2017年8月PX-1井增产相关的地震为1.12; 对于其他油井增产措施，估计相似的值。该分析的结果是，任何地震的概率都可能高达M_W  = 5.5（使用b值通过外推法预测在其出现之前）比所声称的要低得多。该分析突出显示了需要为报告数据集（如此类数据可能影响对EGS开发人员的起诉）达成商定的工作流程规范，以及针对由EGS项目产生的可接受的经济风险的商定规范。