Bayraktar, Hafize Başak (2022) Tsunami scenarios for hazard forecasting based on complex earthquake slip models. [Tesi di dottorato]

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Using homogenous slip distributions as an earthquake and tsunami sources in tsunami hazard analyses is a widespread approach, despite the co-seismic slip distribution complexity has an important impact on the hazard results. Numerous methods have been proposed to generate synthetic heterogenous slip distributions for tsunami hazard calculations (Davies et al., 2015; Le Veque et al., 2016; Murphy et al., 2016; Sepulveda et al., 2017; Scala et al., 2020). Slip distributions informed by kinematic models from inversion of real events are also employed (Goda et al., 2014). However, it is not certain to what extent tsunami waveforms generated by these models are consistent with available tsunami observations. The main goal of this study is to test synthetic tsunamis produced by different slip generation techniques against tsunami observations from open ocean DART buoys. In the study of Davies (2019), a variety of different approaches for tsunami source modelling in subduction zones are tested by comparing the simulated tsunami waveforms with DART records of 18 tsunami events. Davies and Griffin (2020) also analyzed the sensitivity of far-field PTHA to slip and propose a bias-adjustment of synthetic tsunamis produced with variable-area-uniform-slip and heterogeneous-slip models. The approach proposed in Scala et al. (2020) for the generation of depth-dependent stochastic slip models in the context of PTHA is used for generating set of scenarios of magnitude and location similar to all the 15 events on the same geometries used by Davies (2019). Kinematic slip models on planar faults obtained with tele-seismic inversion for 10 out of these 15 events are also present in the earthquake catalog of Ye et al. (2016). In this study, we compare synthetic tsunamis produced by recent stochastic slip generation techniques (Scala et al., 2020) against tsunami observations at open ocean DART buoys, for 15 earthquakes and ensuing tsunamis analyzed also by Davies (2019). In addition to stochastic slip models, 10 kinematic slip models from teleseismic inversions of Ye et al. (2016) for the same 15 earthquakes are also considered as tsunami sources. The modelling results are tested and compared to the others in the same framework proposed by Davies (2019). This also allows to compare the performance of all these models with respect to observations with the source models tested by Davies (2019). Comparison of the variability and bias, as deduced by comparison to observed tsunamis, of all the random earthquake models tested in this study should help us better understand how different slip and rigidity treatments affect the random simulated tsunamis and thus “what factors are important” to reflect the natural variability of real tsunamis in the context of tsunami hazard assessment.

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