研究人员利用Nankai海槽地震活动的独特几何形状，根据经验校准衰减后，分离出低频地震的频谱特征。研究观察到，低频地震谱与经典地震模型一致，但它们的破裂持续时间和应力降与普通地震有数量级的不同。所以研究得出结论，它们的低频性质主要是由非典型的地震破裂过程而不是近源衰减造成的。
研究人员表示，低频地震是不同于常规地震的非典型地震事件，发生在地震成因的巨大逆冲断层的下倾部位，在那里无震流变学控制着俯冲板块边界。它们的独特波形很好地为这种独特的断层环境的滑动状态提供了线索，反映了其震源区不寻常的破裂过程或不寻常的强烈衰减。
附：英文原文
Title: What makes low-frequency earthquakes low frequency
Author: Qing-Yu Wang, William B. Frank, Rachel E. Abercrombie, Kazushige Obara, Aitaro Kato
Issue&Volume: 2023-08-09
Abstract: Low-frequency earthquakes, atypical seismic events distinct from regular earthquakes, occur downdip of the seismogenic megathrust where an aseismic rheology dominates the subduction plate boundary. Well situated to provide clues on the slip regime of this unique faulting environment, their distinctive waveforms reflect either an unusual rupture process or unusually strong attenuation in their source zone. We take advantage of the unique geometry of seismicity in the Nankai Trough to isolate the spectral signature of low-frequency earthquakes after correcting for empirically derived attenuation. We observe that low-frequency earthquake spectra are consistent with the classical earthquake model, yet their rupture duration and stress drop are orders of magnitude different from ordinary earthquakes. We conclude their low-frequency nature primarily results from an atypical seismic rupture process rather than near-source attenuation.
DOI: adh3688
Source: https://www.science.org/doi/full/10.1126/sciadv.adh3688