Local Bathymetry and Shelf Resonance Effects Observed for the Near-field Tsunami Generated by the 2010, Mw 8.8, Maule Earthquake

The Chilean coast has been hit by several far- and near-field tsunamis, for instance the last recent destructive tsunami devastating the Chilean shore was caused by the 2010 M_w 8.8, Maule earthquake. Several long-period waves were recorded away by DART buoys and local eyewitness and field surveys also confirm that incoming waves have hit the shore several hours after the leading wave arrival time. In addition, few published numerical modeling of the Maule near-field tsunami show trapping waves and amplification of the energy over the continental shelf. To better understand the origin of the tsunami wave trains and the continental shelf features as a potential responsible of resonance, we perform tsunami modeling by improving the earthquake source parameters modeling. We generate realistic 3D static displacement of the seafloor to be used as input for tsunami passive generation, propagation and runup estimates along the shore. We meshed the seismogenic contact zone between the Nazca and Sudamerica plates along the Maule region, through a 3D surface. The co-seismic slip distribution solution published for the Maule earthquake were used to model the runup, and trapped waves were observed on the numerical simulations. To further study the hypothesis of that a large magnitude earthquake may generate same kind of hydrodynamic effect, such as, successive tsunami wave trains, we modeled several hypothetical physical-based slip distributions for a Mw 8.8 earthquake rupture. At every subfault we used the Okada's point-source formula to compute the co-seismic static 3D displacement field. Preliminary results, show that a complex geometry of the slab have important effects on the vertical static displacements. We are currently evaluating the tsunami propagation for these hypothetical earthquakes, the study include understanding specific aspects related to local bathymetry, and hydrodynamic effects, among which, flow direction, directivity, reflection, diffraction, focusing/defocussing of water waves, and local shelf resonance.