ALBERT

Description: In the context of response to disasters, fast and accurate simulations can be integrated into a real-time flow, allowing best situation estimates to be provided at required deadlines for warnings and decisions. In such a pilot centered on earthquakes, the TsunAWI tsunami simulation code has been adapted and improved to provide both fast results with a coarse mesh and more accurate results with a fine mesh. Improvements to the TsunAWI code have allowed simulation runs to reach runtimes compatible with the needs of a workflow with real-time deadlines. A significant component of TsunAWI is the underlying mesh traversal order; the use of heuristics from the gpu rendering community can reach comparable performance to the original space filing curve ordering, and validation against historical cases is underway for the fast simulation results.

Description: Accurate and rapid earthquake loss assessments and tsunami early warnings are critical in modern society to allow for appropriate and timely emergency response decisions. In the LEXIS project, we seek to enhance the workflow of rapid loss assessments and emergency decision support systems by leveraging an orchestrated heterogeneous environment combining high-performance computing resources and Cloud infrastructure. The workflow consists of three main applications: firstly, after an earthquake occurs, its shaking distribution (ShakeMap) is computed based on the OpenQuake code. Secondly, if a tsunami may have been triggered by the earthquake, tsunami simulations (first a fast and coarse and later a high-resolution and computationally intensive analysis) are performed based on the TsunAWI simulation code that allows for an early warning in potentially affected areas. Finally, based on the previous results, a loss assessment based on a dynamic exposure model using open data such as OpenStreetMap is performed. To consolidate the workflow and ensure respect of the time constraints, we are developing an extension of a time-constrained dataflow model of computation, layered above and below the workflow management tools of both the high-performance computing resources and the Cloud infrastructure. This model of computation is also used to express tasks in the workflow at the right granularity to benefit from the data management optimisation facilities of the LEXIS project. This paper describes the workflow, the associated computations and the model of computation within the LEXIS platform.

Description: State of the art tsunami warning systems employ a combined approach of pre-computed scenarios and on the fly tsunami simulation in case of an event. The on the fly simulations are performed on rather coarse meshes (approx. 1km resolution), usually neglect e.g., the non-linear advection in the shallow water equations, and can deliver a reasonable estimate of the wave height at the coast within a few seconds of computation time. As in the early warning situation, the earthquake source is the major unknown, they can improve the hazard assessment compared to pre-computed scenarios based on idealized sources. On the other hand, it requires a resolution of approximately 10m on land and the non-linear shallow water equations augmented by terms like the bottom roughness to simulate the inundation in the quality needed to derive risk maps for civil protection measures. With the simulation code TsunAWI, which employs an unstructured triangular mesh to seamlessly change the spatial resolution from a few meters in an area of interest to a few kilometers in the deep ocean, such simulations can be performed with a regional focus in less than 20min computation time. Hence, with a coarsened resolution, a first estimate of the inundation could be provided within a few minutes, improving the near-realtime assessment of the hazard. We investigate which quality of inundation result can be achieved within a limited computation time, regarding computing platforms based on various generations of Intel Xeon from Broadwell to Cascade Lake. This investigation is part of the EU funded LEXIS project lead by It4Innovations, Ostrava, Czech Republic. The overall aim is to build an advanced engineering platform at the confluence of HPC, Cloud and Big Data. Of particular interest is the development of time constrained workflows over HPC and cloud resources, with a pilot combining tsunami simulations and earthquake damage assessment. Fast tsunami inundation estimates are a key element of that pilot.