A numerical methodology for estimating site-specific cascading earthquake and tsunami dynamic loading on critical infrastructure

A numerical methodology for deriving cascading earthquake and tsunami loading patterns for use in critical infrastructure design is proposed. Earthquake source parameters are first used to generate synthetic ground motion acceleration time series at the site of a critical infrastructure using an open-source stochastic extended finite-source simulation algorithm. Using the same earthquake source information, the tsunami phases of generation, propagation, and inundation are modeled using a coupling approach for determining tsunami wave forces. The coupling approach combines (1) a code based on non-linear shallow water equations solved by the Finite Volume method, which is used to capture the tsunami flow characteristics from generation through the inundation phase until relatively close to the structure, coupled with (2) an open -source computational fluid simulation code, which relies on solving the Navier-Stokes equations using the Smoothed Particle Hydrodynamics method. An appendix presents the validation of the numerical methodology through correlation of the numerical simulations with field data recorded during the 2011 Japan Earthquake and Tsunami. The methodology is then employed to characterize the ground shaking and tsunami loading patterns at the site of the container terminal of the Sines deep-water seaport in Portugal, when subjected to the historic 1755 Great Lisbon Earthquake and Tsunami plausible scenarios. For the site, the generated ground motion acceleration time series show peak accelerations exceeding Eurocode 8 design values. Tsunami flow depths and velocities were computed in horizontal and vertical directions and could be used in the assessment of the existing infrastructure or the design of the future expansion of the port.