The generation mechanism of deep earthquakes in subducting slabs remains enigmatic. We analyze five groups of similar earthquakes (depth > 200 km) in the Pacific Plate beneath central Japan, whose waveforms are similar at five or more stations over a 40 s time window that includes the P and S arrivals. Hypocenter relocations using waveform-derived differential-time data suggest that similar deep earthquakes occur on complementary ruptures of neighboring patches on a fault, rather than by repeatedly rupturing the same fault patch. The stress drops of similar earthquakes are almost constant within each group but differ by an order of magnitude even between groups separated by ~20 km, while the scaled energy and radiation efficiency are significantly different even for each group. The wide range of source parameters estimated for similar earthquakes in a common slab environment suggests that source parameters can be significantly affected by small-scale heterogeneities along the fault. Thus, the predominant-rupture process of deep earthquakes can be different even on the same fault plane or at the identical depths in a common slab. A dual process which includes both seismic rupture assisted by fluid-related embrittlement and thermal shear instability might have a possibility to explain the generation mechanism of deep earthquakes.

俯冲平板中深层地震的产生机理仍然是个谜。我们分析了日本中部以下太平洋板块的五组相似地震（深度> 200 km），在包括P和S的40 s时间窗口内，五个或更多台站的波形相似到达。使用波形衍生的时差数据进行的震源重定位表明，类似的深地震发生在断层上邻近斑块的互补破裂上，而不是通过重复破裂相同的断层来发生。相似地震的应力降在每个组中几乎是恒定的，但是即使在相距约20 km的组之间也存在一个数量级的差异，而即使对于每个组，缩放的能量和辐射效率也存在显着差异。在共同的平板环境中，对相似地震的震源参数估计范围很广，这表明震源参数可能会受到沿断层的小规模异质性的显着影响。因此，即使在同一断层平面上或在同一平板中相同深度处，深地震的主要破裂过程也可能不同。