Dr. Aránguiz-Muñoz, Rafael

In 2015 and 2017 unusual ocean and atmospheric conditions produced many years’ worth of rainfall in short periods over Northern Chile’s Atacama Desert, resulting in catastrophic flooding in the town of Chañaral. However, the town is not only at risk of fluvial flooding, it is also at risk of tsunamis. Through a community mapping exercise, the authors attempted to establish the level of community awareness about tsunamis, and contrasted it with that of other types of water-related hazards facing the town (namely that of flooding due to high intensity rain). This was then compared with the results of field surveys and tsunami hazard simulations, indicating than overall the community appears to have better awareness than authorities about the threat posed by these types of events. The authors thus concluded that in cases when the community has a high level of hazard awareness (which in the case of Chile was the result of traditional knowledge being transmitted from previous generations) it would be advantageous to include them in discussions on how to improve disaster resilience.

The variability in obtaining estimates of tsunami inundation and runup on a near‐real‐time tsunami hazard assessment setting is evaluated. To this end, 19 different source models of the Maule Earthquake were considered as if they represented the best available knowledge an early tsunami warning system could consider. Results show that large variability can be observed in both coseismic deformation and tsunami variables such as inundated area and maximum runup. This suggests that using single source model solutions might not be appropriate unless categorical thresholds are used. Nevertheless, the tsunami forecast obtained from aggregating all source models is in good agreement with observed quantities, suggesting that the development of seismic source inversion techniques in a Bayesian framework or generating stochastic finite fault models from a reference inversion solution could be a viable way of dealing with epistemic uncertainties in the framework of nearly‐real‐time tsunami hazard mapping.

On September 16, 2015 a magnitude Mw 8.3 earthquake took place off the coast of the Coquimbo Region, Chile. Three tsunami survey teams covered approximately 700 km of the Pacific coast. The teams surveyed the area, recording 83 tsunami flow depth and runup measurements. The maximum runup was found to be 10.8 m at only one small bay, in front of the inferred tsunami source area. However, it was observed that runup in other locations rarely exceed 6 m. Tsunami runup was larger than those of the 2014 Pisagua event, despite the similar earthquake magnitude. Moreover, tsunami arrival times were found to be shorter than those of previous tsunamis along the Chilean subduction zone. Numerical simulations of the tsunami event showed a good agreement with field data, highlighting that tsunami arrival time and the spatial variation of the tsunami amplitudes were strongly influenced by the bathymetry, coastal morphology and the slip distribution of the causative earthquake.

On 1 April 2014, an earthquake with moment magnitudeMw8.2 occurred off the coast ofnorthern Chile, generating a tsunami that prompted evacuation along the Chilean coast. Here tsunamicharacteristics are analyzed through a combination of field data and numerical modeling. Despite theearthquake magnitude, the tsunami was moderate, with a relatively uniform distribution of runup, whichpeaked at 4.6 m. This is explained by a concentrated maximal slip at intermediate depth on the megathrust,resulting in a rapid decay of tsunami energy. The tsunami temporal evolution varied, with locations showingsustained tsunami energy, while others showed increased tsunami energy at different times after theearthquake. These are the result of the interaction of long period standing oscillations and trapped edgewave activity controlled by inner shelf slopes. Understanding these processes is relevant for the region,which still posses a significant tsunamigenic potential