Geomechanics and Damage Group (GeoD), Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, USA.
Department of Geology and Environmental Earth Science, Miami University, Oxford, OH, USA.
Nat Commun. 2023 Apr 12;14(1):2056. doi: 10.1038/s41467-023-37782-5.
Clustering of earthquake magnitudes is still actively debated, compared to well-established spatial and temporal clustering. Magnitude clustering is not currently implemented in earthquake forecasting but would be important if larger magnitude events are more likely to be followed by similar sized events. Here we show statistically significant magnitude clustering present in many different field and laboratory catalogs at a wide range of spatial scales (mm to 1000 km). It is universal in field catalogs across fault types and tectonic/induced settings, while laboratory results are unaffected by loading protocol or rock types and show temporal stability. The absence of clustering can be imposed by a global tensile stress, although clustering still occurs when isolating to triggered event pairs or spatial patches where shear stress dominates. Magnitude clustering is most prominent at short time and distance scales and modeling indicates >20% repeating magnitudes in some cases, implying it can help to narrow physical mechanisms for seismogenesis.
与已经确立的时空聚类相比，地震震级的聚类仍然存在争议。震级聚类目前并未应用于地震预测中，但如果更大震级的事件之后更有可能发生类似震级的事件，那么它将非常重要。在这里，我们展示了在许多不同的野外和实验室目录中，在广泛的空间尺度（毫米到 1000 公里）上存在具有统计学意义的震级聚类。它在断层类型和构造/诱发环境的野外目录中是普遍存在的，而实验室结果不受加载协议或岩石类型的影响，并且具有时间稳定性。虽然在隔离触发事件对或剪切应力占主导地位的空间斑块时仍会发生聚类，但全局拉伸应力可以强制消除聚类。震级聚类在短时间和短距离尺度上最为明显，并且模型表明在某些情况下会出现>20%的重复震级，这表明它有助于缩小地震成因的物理机制。
