Liu Yuan-Kai, Ross Zachary E, Cochran Elizabeth S, Lapusta Nadia
Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125, USA.
U.S. Geological Survey, Earthquake Science Center, Pasadena, CA 91106, USA.
Sci Adv. 2022 Feb 25;8(8):eabk1167. doi: 10.1126/sciadv.abk1167. Epub 2022 Feb 23.
The San Andreas Fault (SAF) showcases the breadth of possible earthquake sizes and occurrence behavior; in particular, the central SAF is a microcosm of such diversity. This section also exhibits the spectrum of fault coupling from locked to creeping. Here, we show that the observations of aseismic slip, temporal clustering of seismicity, and spatial variations in earthquake size distributions are tightly connected. Specifically, the creep rate along the central SAF is shown to be directly proportional to the fraction of nonclustered earthquakes for the period 1984-2020. This relationship provides a unified perspective of earthquake phenomenology along the SAF, where lower coupling manifests in weaker temporal clustering, with repeating earthquakes as an end-member. This new paradigm provides additional justification for characterizing the northwest ∼75 kilometers of the creeping segment as a transition zone, with potential implications for seismic hazard.
圣安地列斯断层(SAF)展现了可能的地震规模范围和发生行为;特别是,圣安地列斯断层中部是这种多样性的一个缩影。这一区域还展示了从闭锁到蠕动的断层耦合频谱。在此,我们表明对无震滑动、地震活动的时间聚类以及地震规模分布的空间变化的观测紧密相连。具体而言,1984 - 2020年期间,沿圣安地列斯断层中部的蠕动速率与非聚类地震的比例成正比。这种关系为沿圣安地列斯断层的地震现象学提供了一个统一的视角,其中较低的耦合表现为较弱的时间聚类,重复地震则是一种极端情况。这种新范式为将蠕动段西北约75公里的区域表征为一个过渡带提供了额外的依据,这对地震危险性可能具有影响。