Past large earthquakes influence future strong ground motion: Example of the Chilean subduction zone

Large earthquakes in subduction zones harbor significant elastic strain accumulation due the slip deficit (interseismic coupling), posing a major earthquake and tsunami threat to coastal populated areas. Unlike regions that have already released energy, several subduction’s segments remain understudied in terms of its seismic potential. This research is devoted to address this gap by generating a kinematic rupture scenario for the Chilean subduction zone’s Atacama-Metropolitan Segment (AMS) by using the Heterogeneous Energy-Based method which incorporate the complex geometric and frictional heterogeneities of faults. The simulations reveal a potential Mw 8.6 earthquake scenario, characterized by localized bursts of strong ground motion linked to the rupture of asperities. The total rupture area of this scenario also included the region hosting the 2015 Illapel earthquake (Mw 8.3). The zone of this past earthquake contributes minimally to the current rupture scenario by radiating less seismic energy, highlighting the influence of past events on future earthquake’s asperities distributions, strong ground motion and tsunami risk. Furthermore, this rupture scenario could generate peak ground accelerations exceeding 0.8 g in coastal cities and can induce potential seafloor uplift of 2–3 m, warranting further studies of tsunami risk. Thus, this study demonstrates the critical importance of considering fault’s heterogeneities and the influence of past earthquakes in subduction zones when assessing seismic risk.