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

Abstract

Large earthquakes in subduction zones harbor significant elastic strain accumulation duethe slip deficit (interseismic coupling), posing a major earthquake and tsunami threat tocoastal populated areas. Unlike regions that have already released energy, several subduction’s segments remain understudied in terms of its seismic potential. This research isdevoted to address this gap by generating a kinematic rupture scenario for the Chileansubduction zone’s Atacama-Metropolitan Segment (AMS) by using the HeterogeneousEnergy-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 Illapelearthquake (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 pastevents on future earthquake’s asperities distributions, strong ground motion and tsunamirisk. 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, warrantingfurther studies of tsunami risk. Thus, this study demonstrates the critical importance ofconsidering fault’s heterogeneities and the influence of past earthquakes in subductionzones when assessing seismic risk.