Tsunami hazard assessment in El Salvador, Central America, from seismic sources through flooding numerical models

ABSTRACT. El Salvador is the smallest and most densely populated country in Central America; its coast has an approximate lenght of 320 km, 29 municipalities and more than 700.000 inhabitants. In El Salvador there were 15 recorded tsunamis between 1859 and 2012, 3 of them causing damages and resulting in hundreds of victims. Hazard assessment is commonly based on propagation numerical models for earthquake-generated tsunamis and can be approached through both probabilistic and deterministic methods. A deterministic approximation has been applied in this study as it provides essential information for coastal planning and management. The objective of the research was twofold: on the one hand the characterization of the threat over the entire coast of El Salvador, and on the other the computation of flooding maps for the three main localities of the Salvadorian coast. For the latter we developed high-resolution flooding models. For the former, due to the extension of the coastal area, we computed maximum elevations maps, and from the elevation in the near shore we computed an estimation of the run-up and the flooded area using empirical relations. We have considered local sources located in the Middle America Trench, characterized seismotectonically, and distant sources in the rest of Pacific Basin, using historical and recent earthquakes and tsunamis. We used a hybrid finite differences-finite volumes numerical model in this work, based on the linear and non-linear shallow water equations, to simulate a total of 24 earthquake-generated tsunami scenarios. Our results show that at the wastern Salvadorian coast, run-up values higher tan 5 m. are common, while in the eastern area, approximately from La Libertad to the Gulf of Fonseca, the run-up values are lower. The more exposed areas to flooding are the lowlands in the Lempa River delta and the Barra de Santiago Western Plains. The results of the empirical approximation used for the whole country are similar to the results obtained with the high-resolution numerical modelling, being a good and fast approximation to obtain preliminary tsunami hazard estimations. In Acajutla and La Libertad, both important tourism centres being actively developed, floodings dephts between 2 and 4 m are frequent, accompanied with high and very high person instability hazard. Inside the Gulf of Fonseca the impact of the waves is almost negligible

Integrated tsunami vulnerability and risk assessment: application to the coastal area of El Salvador

ABSTRACT. Advances in the understanding and prediction of tsunami impacts allow for the development of risk reduction strategies for tsunami-prone areas. This paper presents a tsunami vulnerability and risk assessment for the case study of El Salvador, the applied methodology dealing with the complexity and variability of coastal zones by means of (i) an integral approach to cover the entire risk-related process from the hazard, vulnerability and risk assessments to the final risk management; (ii) an integrated approach to combine and aggregate the information stemming from the different dimensions of coupled human and natural systems; and (iii) a dynamic and scale-dependent approach to integrate the spatiotemporal variability considerations. This work also aims at establishing a clear connection to translate the vulnerability and risk assessment results into adequate target-oriented risk reduction measures, trying to bridge the gap between science and management for the tsunami hazard. The approach is applicable to other types of hazards, having been successfully applied to climate-change-related flooding hazard

Tsunami evacuation modelling as a tool for risk reduction: application to the coastal area of El Salvador

ABSTRACT. Advances in the understanding and prediction of tsunami impacts allow the development of risk reduction strategies for tsunami-prone areas. This paper presents an integral framework for the formulation of tsunami evacuation plans based on tsunami vulnerability assessment and evacuation modelling. This framework considers (i) the hazard aspects (tsunami flooding characteristics and arrival time), (ii) the characteristics of the exposed area (people, shelters and road network), (iii) the current tsunami warning procedures and timing, (iv) the time needed to evacuate the population, and (v) the identification of measures to improve the evacuation process. The proposed methodological framework aims to bridge between risk assessment and risk management in terms of tsunami evacuation, as it allows for an estimation of the degree of evacuation success of specific management options, as well as for the classification and prioritization of the gathered information, in order to formulate an optimal evacuation plan. The framework has been applied to the El Salvador case study, demonstrating its applicability to sitespecific response times and population characteristics

A methodology for tsunami hazard and risk assessment: application to the coastal area of El Salvador

Advances in the understanding and prediction of tsunami impacts allow the development of adaptation and mitigation strategies to reduce risk on coastal areas. This work, funded by the Spanish Agency for International Development Cooperation (AECID) during the period 2009-2012, presents a comprehensive methodology for tsunami risk assessment at any coastal area worldwide applied specifically in this case to the coast of El Salvador

Desarrollo de una metodología para el estudio de la morfología de playas basado en mapas auto-organizativos de imágenes digitales

RESUMEN: El uso de cámaras de video para obtener información de la zona costera se ha extendido en los últimos años, debido al alcance espacial y temporal y el bajo costo del equipo. Con esto se han desarrollado técnicas para realizar mediciones en las imágenes. Estas requieren supervisión, lo que limita el número de imágenes que pueden ser analizadas. En este trabajo se desarrolló una metodología para clasificar imágenes digitales según las características morfodinámicas observadas y reducir el conjunto de imágenes a unos prototipos representativos de todo el conjunto. Esta clasificación se realiza por medio de mapas auto-organizativos. Los mapas auto organizativos son redes neuronales competitivas no supervisadas diseñadas para trabajar en espacios multidimensionales. La metodología desarrollada se aplico en dos playas; la primera, macromareal, se estudio la evolución morfodinámica según el modelo de Wright y Short 1984. En la segunda, micromareal, se estudio, la evolución de la línea de costa.ABSTRACT: The use of video cameras to study the coastal zone has been developed in the last years, due to the spatial and temporal possibilities. A large number of techniques to obtain measurements of images were developed too. Most of these techniques require the human supervision, this limit the number of images to be analyzed. In this Thesis, a methodology to classify digital images based on the morphodynamic and reduce the number of images to a few prototypes is proposed. The classification is done by means of Sel-Organizative Maps (SOMs). The SOMs are a competitive and unsupervised neural networks, specifically designed to deal with high dimensional data The methodology proposed was applied to two beaches. In the first one, macrotidal, the morphodynamic evolution was studied using the Wright and Short Model 1984. In the last one, a microtidal beach, the coastline evolution was studied

SMC e , a coastal modeling system for assessing beach processes and coastal interventions: Application to the Brazilian coast

A user-friendly system designed to understand local littoral processes and design/evaluate coastal interventions, named the Coastal Modeling System (SMC e ) is presented. The system, which comprises a set of numerical models, state-of-the-art methodologies and numerical databases, is prepared to provide a method for coastal practitioners, researchers and decision-makers to address coastal issues, such as erosion and flooding or to evaluate coastal defense structures. The system incorporates a method to transfer numerically generated, calibrated and validated wave series to the surf zone; to estimate the sediment littoral drift by means of up-to-date formulations; and to estimate the flooding level and impacts such as those produced by climate change. In this paper, these skills are detailed. The system, which is adaptable to any coastal region, was implemented for the Brazilian coast (SMC-Brasil). The implementation includes databases and methodological adaptations to local characteristics, a dissemination plan and the development of several study cases.Peer Reviewe