Dynamic Triggering of Deep Earthquakes—a Global Perspective

Abstract:

Dynamic triggering has been robustly observed for shallow earthquakes and tremor. Understanding this phenomenon provides important constraints on earthquake dynamics, such as earthquake nucleation, fault frictional properties, slow slip, and stress distributions. Tibi et al. (2003) reported examples of dynamic triggering in deep earthquakes and pointed out their potential to constrain the still-enigmatic faulting mechanisms of deep earthquakes. Here we analyze global earthquake catalogs to systematically search for statistically significant dynamic triggering at depths greater than 300 km. We find that dynamic triggering of deep earthquakes is most pronounced within 3 hours after the master events, and is limited in depth (i.e., triggering of and by shallow earthquakes is not observed). We also observed a significant downward triggering bias. We suggest that these characteristics may be related to deep earthquake rupture directivity and meta-stable olivine wedge structures inside subducted slabs.