HySEA model verification for Tohoku 2011 Tsunami. Application for mitigation tsunami assessment

In many aspects Tohoku-Oki 2011 mega tsunami has changed our perception of tsunami risk. The tsunami-HySEA model is used to numerically simulate this event and observed data will we used to verify the model results. Three nested meshes of enhanced resolution (4 arc-min, 32 arc-sec and 2 arc-sec) will be used by the numerical model. The propagation mesh covers all Pacific Ocean with more of 7 million cells. An intermediate mesh with 5 millions cells contains the Japanese archipelago and, finally, two finer meshes, with nearly 8 and 6 millions cells, cover Iwate and Miyagi Prefectures at Tohoku region, the most devastated areas hit by the tsunami. The presentation will focus on the impact of the tsunami wave in these two areas and comparisons with observed data will be performed. DART buoys time series, inundation area and observed runup is used to assess model performance. The arrival time of the leading flooding wave at the vicinity of the Senday airport, as recorded by video cameras, is also used as verification data for the model. After this tsunami, control forests as well as breakwaters has been discussed as suitable mitigation infrastructures. As particular case, we will analyse the evolution of the tsunami in the area around the Sendai airport (Miyagi Prefecture) and its impact on the airport. A second simulation has been performed, assuming the existence of a coastal barrier protecting the area. The role of this barrier in modifying tsunami wave evolution and mitigating flooding effects on the airport area are discussed. The protection effect of the breakwaters near Kamaishi (Iwate Prefecture) is also assessed. The numerical model shows how these structures, although did not provide a full protection to tsunami waves, they helped to largely mitigate its effects in the area.Acknowledgements. This research has been partially supported by the Junta de Andalucía research project TESELA (P11-RNM7069), the Spanish Government Research project DAIFLUID (MTM2012-38383-C02-01) and Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tech. The multi-GPU computations were performed at the Laboratory of Numerical Methods (University of Malaga)

Efficient multilayer shallow-water simulation system based on GPUs

The computational simulation of shallow stratified fluids is a very active research topic because these types of systems are very common in a variety of natural environments. The simulation of such systems can be modelled using multilayer shallow-water equations but do impose important computational requisites especially when applied to large domains. General Purpose Computing on Graphics Processing Units (GPGPU) has become a vivid research field due to the arrival of massively parallel hardware platforms (based on graphics cards) and adequate pro- gramming frameworks which have allowed important speed-up factors with respect to not only sequential but also parallel CPU based simulation systems. In this work we present a proposal for the simulation of shallow stratified fluids with an arbitrary number of layers using GPUs. The designed system does fully adapt to the many-core architecture of modern GPUs and several experiments have been carried out to illustrate its scalability and behavior on different GPU models. We propose a new elaborated 3D computational scheme for an underlying 2D mathematical model. This scheme allowed implementing a system capable of handling an arbitrary number of layers. The system adds no overhead when used for two-layer scenarios, compared to an existing 2D system specifically designed for just two layers. Our proposal is aimed at creating a GPU-based computational scheme suitable for the simulation of multilayer large-scale real-world scenarios.P11-FQM8179P11-RNM7069MTM2012-38383-C02-0

HySEA: An operational GPU-based model for Tsunami Early Warning Systems

HySEA numerical model for the simulation of earthquake generated tsunamis is presented. The initial sea surface deformation is computed using Okada model. Wave propagation is computed using nonlinear shallow water equations in spherical coordinates, where coastal inundation and run-up are suitable treated in the numerical algorithm. Generation, propagation and inundation phases are all integrated in a single code and computed coupled and synchronously when they occur at the same time. Inundation is modelled by allowing cells to dynamically change from dry to wet and reciprocally when water retreats from wetted areas. Special effort is made in preserving model well-balanced (i.e. capturing small perturbations to the steady state of the ocean at rest). The GPU model implementation allows faster than real time (FTRT) simulation for real large-scale problems. The large speed-ups obtained make HySEA code suitable for its use in Tsunami Early Warning Systems. The Italian TEWS at INGV (Rome) has adopted HySEA GPU code for its National System. The model is verified by hindcasting the wave behaviour in several benchmark problems. Numerical results for an earthquake-generated tsunami in the Mediterranean Sea is presented and computing time analysed. The interest of using higher order methods, analysing numerical schemes from first order up to order five, in the context of TEWS, is also addressed. Tsunami codes do not usually use higher than second order methods. It is demonstrated that this should idea should be revised.This research has been partially supported by the Junta de Andalucía research project TESELA (P11-RNM7069), the Spanish Government Research project HySEA2 (MTM2009-11923) and Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tech. The multi-GPU computations were performed at the Laboratory of Numerical Methods (University of Malaga)

2D GPU-based HySEA model for tsunami simulation. Some practical examples.

A two-waves TVD-WAF type scheme for solving 2D shallow-water equation is considered together with a first and second order HLL scheme. Comparison among the different schemes will be performed to check the performance for the proposed one. A description of the GPU implementation will be presented as well as some applications to tsunami simulation in real topo-bathymetries.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Deslizamientos submarinos y tsunamis en el Mar de Alborán. Un ejemplo de modelización numérica

Texto científico de carácter divulgativo.Texto científico de carácter divulgativo en el que se presenta un trabajo de modelado matemático y simulación numérica de un hipotético tsunami producido en el Mar de Alborán por un deslizamiento masivo de materiales en el flanco sur de la Dorsal de Alborán.Instituto Español de Oceanografía. Universidad de Málaga

Deslizamientos submarinos y tsunamis en el Mar de Alborán. Un ejemplo de modelización numérica

Los componentes principales de este libro son: a) conocer y estudiar determinados fenómenos naturales de consecuencias catastróficas, como los tsunamis, y b) identificar los útiles científicos para representar estos fenómenos. Por ello, es necesario disponer de un profundo conocimiento del fondo marino donde se produce el fenómeno, conocimiento que proviene del análisis de datos geológicos y geofísicos, y por otro lado, es encesario hacer uso de la potencialidad de los modelos matemáticos que permiten realizar simulaciones numéricas precisas. El libro presenta los resultados de la simulación numérica de un tsunami generado en la cuenca del Mar de Alborán y su propagación e interacción con la morfología submarina de dicho área geográfica.Versión del edito

The EU Center of Excellence for Exascale in Solid Earth (ChEESE): Implementation, results, and roadmap for the second phase

publishedVersio

Desarrollo de software numérico de simulación de flujos geofísicos basado en volúmenes finitos usando hardware gráfico

Tesis Univ. Granada. Departamento de Lenguajes y Sistemas InformáticosEste trabajo descrito en esta tesis doctoral ha sido parcialmente subvencionado por los proyectos DGI-MEC MTM2008-06349-C03-03, DGI-MEC MTM2009-11923 y DGI-MICINN MTM2011-27739-C04-02

Numerical simulation of tsunamis generated by landslides on multiple GPUs

In this work we propose a two-layer Savage–Hutter type model that is the natural extension of the 1D system proposed by E. D. Fernández-Nieto et al in 2008 to simulate tsunamis generated by landslides. We describe a single GPU and a multi-GPU implementation of this model using MPI and the CUDA framework over structured meshes. The distributed implementation is tested for several artificial and realistic problems using up to 24 GPUs. We also propose a static and a dynamic load balancing algorithm in order to deal with the unbalanced computational load due to different amount of wet and dry areas among the subdomains. The validity of the model is tested by simulating the tsunami occurred in Lituya Bay, Alaska, in 1958. Numerical experiments show the efficiency of the multi-GPU solver, the usefulness of the load balancing algorithms and the validity of the model to simulate real tsunamis generated by landslides.En este trabajo proponemos un modelo tipo Savage-Hutter de dos capas que es la extensión natural del sistema 1D propuesto por E. D. Fernández-Nieto y otros en 2008 para simular tsunamis generados por deslizamientos de tierra. Describimos una implementación de este modelo en una GPU y en varias GPUs utilizando MPI y el framework CUDA sobre mallas estructuradas. La implementación distribuida se prueba para varios problemas artificiales y realistas utilizando hasta 24 GPUs. También proponemos un algoritmo de equilibrado de carga estático y otro dinámico para hacer frente a la carga computacional desequilibrada debida a la diferente cantidad de zonas húmedas y secas entre los subdominios. La validez del modelo se comprueba simulando el tsunami ocurrido en Lituya Bay, Alaska, en 1958. Los experimentos numéricos muestran la eficacia del resolvedor multi-GPU, la utilidad de los algoritmos de equilibrado de carga y la validez del modelo para simular tsunamis reales generados por deslizamientos de tierra.Grupo de Investigación EDANYA de la Universidad de Málag