Dr. Aranguiz-Muñoz, Rafael

Tsunamis are among the most significant hazards in coastal settlements. Mitigation measures have been focused mainly on physical aspects, and few studies have addressed vulnerability and resilience in a multidimensional approach. The main objective of the present work is to assess changes in vulnerability and, consequently, risk, considering a time-space dimension. Three deterministic tsunami scenarios based on historical events were analyzed, and vulnerability analysis with an emphasis on social cohesion and community organization in prereconstruction (2012) and post-reconstruction (2017) conditions was carried out using physical, socioeconomic and social organization variables. The extreme scenario was found to be a 2010-like tsunami, and high levels of social trust and community cooperation were found in pre-reconstruction conditions, which decreased in post-reconstruction conditions due to the relocation of the affected population to other parts of the region. Therefore, it can be concluded that even though physical aspects are important for improving the livability of an affected place and the quality of life of its inhabitants, intentionally biased reconstruction processes (focused mainly on physical aspects) do not effectively reduce risk. Finally, it is crucial to include social capital and social resilience in public policies to implement more comprehensive and successful reconstruction processes.

A large earthquake and tsunami took place in February 2010, affecting a significant part of the Chilean coast (Maule earthquake, Mw of 8.8). Dichato (37° S), a small town located on Coliumo Bay, was one of the most devastated coastal areas and is currently under reconstruction. Therefore, the objective of this research is to analyze the risk factors that explain the disaster in 2010, as well as perceived restoration 6 years after the event. Numerical modeling of the 2010 Chile tsunami with four nested grids was applied to estimate the hazard. Physical, socioeconomic and educational dimensions of vulnerability were analyzed for pre- and post-disaster conditions. A perceived restoration study was performed to assess the effects of reconstruction on the community. It was focused on exploring the capacity of newly reconstructed neighborhoods to provide restorative experiences in case of disaster. The study was undertaken using the perceived restorativeness scale. The vulnerability variables that best explained the extent of the disaster were housing conditions, low household incomes and limited knowledge about tsunami events, which conditioned inadequate reactions to the emergency. These variables still constitute the same risks as a result of the reconstruction process, establishing that the occurrence of a similar event would result in a similar degree of devastation. For post-earthquake conditions, it was determined that all neighborhoods have the potential to be restorative environments soon after a tsunami. However, some neighborhoods are still located in areas devastated by the 2010 tsunami and again present high vulnerability to future tsunamis.