Testing the simulation setup for the GTM PTHA

Global Tsunami Model (GTM) Probabilistic Tsunami Hazard Assessment (PTHA) is one of the Pilot Demonstrators (PD) of the EuroHPC JU ChEESE-2P project, within the scope of GTM organization. As an updated version of Davies et al. (2018) global model, this new one will include enhanced features such as stochastic slip models, spatially higher resolution of the calculation points with particular attention to relatively small islands, and the contribution of tides and long-term sea level variations, among other things. We also aim to make it interoperable with the GEM OpenQuake tools and consistent with similar seismic hazard models.

As an initial step, a tsunami Green's functions (GF) database for subduction zones (meshed as quadrilateral subfaults) in the Pacific Ocean was created on to CINECA Leonardo supercomputer. This database is being used to set up simulations of tsunami GFs on a global grid, using sources in the Pacific Ocean, which will be used for the GTM PTHA. An optimal trade-off between the available computational and storage resources and the resolution/duration and accuracy of the numerical simulations is being sought for. We are also using real events’ tsunami records to determine whether the initial model settings are adequate for accurately modelling observed data, following the approach by Davies (2019).

We will also report about the testing  the new version of Tsunami-HySEA that implements the computation of initial conditions from triangular subfaults (Nikkhoo & Walters, 2015), including the contribution of the horizontal deformation (Tanioka & Satake, 1996), and the “Nosov” filter (Abbate et al., 2024).

Davies, G., Griffin, J., Løvholt, F., Glimsdal, S., Harbitz, C., Thio, H. K., et al. (2018). A global probabilistic tsunami hazard assessment from earthquake sources. Geological Society, London, Special Publications 456, 219–244. doi: 10.1144/sp456.5

Davies, G. (2019). Tsunami variability from uncalibrated stochastic earthquake models: tests against deep ocean observations 2006–2016. Geophysical Journal International, 218(3), 1939-1960.

Nikkhoo, M., & Walter, T. R. (2015). Triangular dislocation: an analytical, artefact-free solution. Geophysical Journal International, 201(2), 1119-1141.

Tanioka, Y., & Satake, K. (1996). Tsunami generation by horizontal displacement of ocean bottom. Geophysical research letters, 23(8), 861-864.

Abbate, A., González Vida, J. M., Castro Díaz, M. J., Romano, F., Bayraktar, H. B., Babeyko, A., & Lorito, S. (2024). Modelling tsunami initial conditions due to rapid coseismic seafloor displacement: efficient numerical integration and a tool to build unit source databases. Natural Hazards and Earth System Sciences, 24(8), 2773-2791.