Deep earthquakes occur down to 700 km depth where pressure is up to two orders of magnitude greater than in the crust. Rupture characteristics and propagation mechanisms under those extreme conditions are still poorly constrained. We invert seismic waveforms for the spatial dimensions, duration and stress drop of deep-focus earthquakes (M_w 6.7–7.7) in the Kuril subduction zone. We find stress drops of ∼1–10 MPa and rigidity-corrected spatial dimensions and durations similar to crustal earthquakes. Radiated efficiency >1 is observed, suggesting that undershooting is prevalent in deep earthquakes, consistent with laboratory derived weakening mechanisms. Comparisons with subduction models suggest across-slab propagation within regions with temperatures T < ∼ 1,000°C, similar to shallow events. Hence, despite different triggering mechanisms, the same physics seems to control the rupture propagation of both shallow and deep earthquakes.

中文翻译：

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千岛俯冲带深部地震的跨板传播和低应力降

深地震发生在 700 公里深度，那里的压力比地壳大两个数量级。在这些极端条件下的破裂特性和传播机制仍然受到很差的约束。我们反转了千岛俯冲带深源地震（M _{w 6.7-7.7）的空间维度、持续时间和应力降的地震波形。}我们发现应力下降约 1-10 MPa，经刚度校正的空间尺寸和持续时间与地壳地震相似。观察到辐射效率 > 1，表明在深地震中普遍存在下冲现象，这与实验室推导的弱化机制一致。与俯冲模型的比较表明温度为T的区域内的跨板传播 < ∼ 1,000°C，类似于浅层事件。因此，尽管触发机制不同，但相同的物理学似乎控制着浅层和深层地震的破裂传播。