The worrying consequences of the 2010 Maule earthquake and tsunami led to significant advances in tsunami research in Chile. These advances were rapidly reflected by improved technical, administrative and social response strategies in response to tsunamis that occurred farther north in 2014 and 2015. In spite of this progress, much remains to be explored in terms of tsunami risk assessment and mitigation planning. This is particularly important in research areas focused on the hazard component that drives tsunami risk. For example, little or no effort has been made in assessing tsunami hazards that consider heterogeneous slip scenarios, as those commonly inferred from geodetic data for megathrust earthquakes in most subduction zones. One of these scenarios includes triggered splay faults rooted in the megathrust, which have received increased attention in recent years due to their tsunamigenic potential. These reverse or normal faults, which branch upwards from the shallow plate interface and may reach the surface, are considered as an import mechanism in tsunami generation due to their steeper dip angles with respect to the megathrust, which may result in enhance seafloor uplift, which in turn controls tsunami heights at the coast. In spite of the evident tsunamigenic potential of splay faults, little effort has been devoted worldwide to investigate their effects on the hydrodynamic characteristics of the resulting tsunamis. Here, we use recent knowledge gained from geophysical observations to explore the potential effects that splay fault triggering may have on near-shore tsunami characteristics along the Chilean coast. Particularly, we compare amplitudes, inundation areas and spectral characteristics of tsunamis predicted from a suite of hypothetical megathrust earthquake scenarios with and without accompanying splay fault triggering. We also explore the effects of the geometry and location of splay faults based on synthetic geometries and branching depths. We further attempt to test hypotheses of splay fault triggering during the 1960 Chile tsunami by comparing observations of tsunamis and land-level changes with those predicted by different hypothetical sources constructed from geometries of splay fault candidates inferred from geophysical images. This study is supported by Iniciativa Científica Milenio through grant NC160025 Millennium Nucleus CYCLO: The Seismic Cycle along Subduction Zones.
Exploring the potential effects of splay faulting triggered by megathrust earthquakes on tsunami hazards in Chile
