Browsing by Author "Zamora, Natalia"

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    An Updated Recurrence Model for Chilean Subduction Seismicity and Statistical Validation of Its Poisson Nature
    (2019) Poulos Campbell, Alan John; Monsalve, Mauricio; Zamora, Natalia; Llera Martin, Juan Carlos de la
    Earthquake recurrence models are the basis of seismic hazard analysis and seismic risk evaluation of physical infrastructure. They are based on statistical analysis of earthquake occurrence data available in a specific geographical region. This work proposes a new earthquake recurrence model for the interface and intraslab seismicity of the subduction margin along Chile. The model improves some of the shortcomings of previous available models in the region such as the lack of earthquake declustering or the use of magnitude scales inconsistent with modern ground‐motion prediction equations. Significant differences in seismic rates are found with some previous models. Indeed, the resulting frequencies from the Gutenberg–Richter relations are not only similar to some of the previous works, but also one order of magnitude higher and lower than two of the previously reported models. Because one of the strongest assumptions in earthquake occurrence models is that they follow a homogeneous Poisson process, this hypothesis is statistically tested herein, finding that the declustered catalog only partially complies with this assumption, showing for instance that the interevent times follow approximately an exponential distribution.
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    Systematic Comparison of Tsunami Simulations on the Chilean Coast Based on Different Numerical Approaches
    (2022) Harig, Sven; Zamora, Natalia; Gubler, Alejandra; Rakowsky, Natalja
    Tsunami inundation estimates are of crucial importance to hazard and risk assessments. In the context of tsunami forecast, numerical simulations are becoming more feasible with the growth of computational power. Uncertainties regarding source determination within the first minutes after a tsunami generation might be a major concern in the issuing of an appropriate warning on the coast. However, it is also crucial to investigate differences emerging from the chosen algorithms for the tsunami simulations due to a dependency of the outcomes on the suitable model settings. In this study, we compare the tsunami inundation in three cities in central Chile (Coquimbo, Vina del Mar, and Valparaiso) using three different models (TsunAWI, Tsunami-HySEA, COMCOT) while varying the parameters such as bottom friction. TsunAWI operates on triangular meshes with variable resolution, whereas the other two codes use nested grids for the coastal area. As initial conditions of the experiments, three seismic sources (2010 Mw 8.8 Maule, 2015 Mw 8.3 Coquimbo, and 1730 Mw 9.1 Valparaiso) are considered for the experiments. Inundation areas are determined with high-resolution topo-bathymetric datasets based on specific wetting and drying implementations of the numerical models. We compare each model's results and sensitivities with respect to parameters such as bottom friction and bathymetry representation in the varying mesh geometries. The outcomes show consistent estimates for the nearshore wave amplitude of the leading wave crest based on identical seismic source models within the codes. However, with respect to inundation, we show high sensitivity to Manning values where a non-linear behaviour is difficult to predict. Differences between the relative decrease in inundation areas and the Manning n-range (0.015-0.060) are high (11-65%), with a strong dependency on the characterization of the local topo-bathymery in the Coquimbo and Valparaiso areas. Since simulations carried out with such models are used to generate hazard estimates and warning products in an early tsunami warning context, it is crucial to investigate differences that emerge from the chosen algorithms for the tsunami simulations.
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    The 1730 Great Metropolitan Chile Earthquake and Tsunami Commemoration: Joint Efforts to Increase the Country's Awareness
    (2020) Zamora, Natalia; Gubler, Alejandra; Orellana, Victor; Leon, Jorge; Urrutia, Alejandro; Carvajal, Matias; Cisternas, Marco; Catalan, Patricio; Winckler, Patricio; Cienfuegos, Rodrigo; Karich, Cristobal; Vogel, Stefan; Galaz, Jose; Pereira, Sebastian; Bertin, Celeste
    On 8 July 1730, a great earthquake struck metropolitan Chile, causing extensive damage 1000 km along the country and focused in Valparaiso. Due to the date of occurrence of this event, large uncertainties about the earthquake's magnitude have been discussed among the scientific community, and the earthquake and tsunami have remained unknown for most of the population. The purpose of this paper is to describe joint efforts undertaken by organizations, academia, and authorities to rescue the forgotten memory of an event that occurred almost three centuries ago and that may be repeated in the near future. In line with the Sendai Framework, we focus on one of the four priorities for action, which is to understand disaster risk, with the premise that the memory activation and raising awareness can save lives in the future. We designed outreach strategies to communicate this knowledge to the community in a participatory way. The latter involves scientific talks, earthquake simulators, tsunami projection mapping on relief scaled models (mock-up), and a public debate including the participation of academia, politicians, authorities, and the local community. The emulation of such activities and the constant work of regional and national authorities, academia, and non-governmental organizations dealing with risk mitigation encourage involving the community to build safer cities against the tsunami hazard.