Gabriel Alice-Agnes, Garagash Dmitry I, Palgunadi Kadek H, Mai P Martin
Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA.
Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany.
Science. 2024 Jul 26;385(6707):eadj9587. doi: 10.1126/science.adj9587.
Earthquakes vary in size over many orders of magnitude, often rupturing in complex multifault and multievent sequences. Despite the large number of observed earthquakes, the scaling of the earthquake energy budget remains enigmatic. We propose that fundamentally different fracture processes govern small and large earthquakes. We combined seismological observations with physics-based earthquake models, finding that both dynamic weakening and restrengthening effects are non-negligible in the energy budget of small earthquakes. We established a linear scaling relationship between fracture energy and fault size and a break in scaling with slip. We applied this scaling using supercomputing and unveiled large dynamic rupture earthquake cascades involving >700 multiscale fractures within a fault damage zone. We provide a simple explanation for seismicity across all scales with implications for comprehending earthquake genesis and multifault rupture cascades.
地震的规模在多个数量级上各不相同，常常在复杂的多断层和多事件序列中发生破裂。尽管观测到的地震数量众多，但地震能量预算的标度关系仍然是个谜。我们提出，大小地震由根本不同的破裂过程控制。我们将地震学观测与基于物理的地震模型相结合，发现动态弱化和再强化效应在小地震的能量预算中都不可忽略。我们建立了破裂能量与断层大小之间的线性标度关系以及与滑动的标度间断。我们利用超级计算机应用这种标度关系，揭示了在断层损伤区内涉及700多条多尺度裂缝的大型动态破裂地震级联。我们对所有尺度的地震活动性给出了一个简单解释，这对理解地震成因和多断层破裂级联具有启示意义。
