On The Use of Empirical Green Functions to Generate Synthetic Tsunami Waveform Catalogs

In this study, we present a methodology to generate a tsunami waveform synthetic catalogue (TWSC) for some coastal locations, compatible with geodynamic constraints of the area of interest. We apply it to the assessment of the tsunami hazard related to Gloria Fault a segment of the Nubia-Eurasia plate boundary between Iberia and the Azores. We focus on earthquake generated tsunamis only. To do this, we assume that the time and space distribution of the seismic events is known. Without a formal way to relate earthquake hazard and tsunami hazard statistics, we have to simulate the tsunami impact (tsunami wave height) along the coast from the largest number of possible earthquake scenarios. However, the computational resources required to perform the tsunami simulation make this process time-consuming.We generate a synthetic earthquake catalogue that includes all fault parameters needed to characterise and compute the seafloor deformation. The time and space rupture distribution is kept compatible with global plate kinematic models. We use Tsunami Empirical Green Functions (EGF) to compute extensively a large number of synthetic tsunami waveforms for all sources included in the synthetic catalogue and all coastal locations. We present a TWSC for a time span of 20kyr, and we analyse tsunami impact regarding wave heights.The advantages of the method consist in the fact that while we keep the geodynamic constraints of the study area we allow some variability of all seismic source parameters to reproduce better, the variability observed in real catalogues. On the other hand, the use of EGF to do the forward tsunami modelling proves to be efficient and less time consuming than traditional forward modelling to compute tsunami waveforms from a massive e number of earthquake scenarios.The application of the method to the Gloria fault case proved to be successful. As expected, the results show that these events pose a minor threat to northern part of the North East Atlantic basin (north of Portugal) and towards the Strait of Gibraltar.This work received funding from project ASTARTE - Assessment Strategy and Risk Reduction for Tsunamis in Europe, Grant 603839, FP7-ENV2013 6.4-3, and project TSUMAPS - NEAM (DG-ECHO, EU)