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This dissertation work concerns the effects of earthquake source geometry on nearfield ground-motions. Through numerical simulations, we investigate the following topics: (1) the effects of listricity on near-field ground motions, and (2) possible ground shaking levels in the Gulf of Aqaba region through multiple earthquake scenarios characterized by several fault segments rupturing either separately or jointly. Listric faults are defined as curved faults in which dip decreases with depth, resulting in a concave upwards profile. The profiles in this study are created by applying a specific shape function: by varying the initial dip and the degree of listricity, we create an ensemble of listric faults. We then define heterogeneous rupture speeds and slip distributions to generate a variety of kinematic source models. Finally, we compare them in terms of peak ground velocities to ground motion prediction equations and find two general features: (1) as listricity increases, the PGVs decrease on the footwall and increase on the hanging-wall; (2) constructive interference of seismic waves emanated from the listric fault causes PGVs over two times higher than those observed for the planar fault. The Gulf of Aqaba region has seen rapid growth in recent years, mainly fuelled by the increasing population, tourism, and investments in national projects. Such projects include the 26.500 km2 city of NEOM, backed by a 500 billion dollar investment by the Saudi Investment Fund and the King Salman bridge across the Straits of Tiran. The recency of the seismic network in the area provides limited information; moreover, no large earthquakes have occurred since its installation. The corresponding lack of data presents engineers with a severe knowledge gap. To contribute to closing this gap, we compute synthetic earthquake ground motions to study the consequences of large magnitude (Mw ~ 7.2) scenario seismic events. To this end, we conduct kinematic rupture simulations that mimic dynamic source behavior including both single- and multi-segment ruptures. Our simulations show higher ground velocities than predicted by GMPEs for the Straits of Tiran and lower for the NEOM area.

Ground motion estimation and subsurface exploration are main research areas in computational seismology, they are fundamental for implementing earthquake engineering requirements and for modern subsurface reservoir assessment. In this study we propose a workflow for discretizing, simulating and visualizing near source ground motion due to earthquake rupture. For data generation we use an elastic wave equation solver called SeisSol based on the Discontinuous Galerkin formulation with Arbitrary high-order DERivatives (ADER-DG). SeisSol is capable of highly accurate treatment of any earthquake source characterization, occurring on geometrically complex fault systems embedded in geologically complicated earth structures. We then visualize the results with two tools: VisIt (“a free interactive parallel visualization and graphical analysis tool for viewing scientific data”) and Avizo (“The 3D Analysis Software for Scientific and Industrial data”). We investigate each approach, include our experiences from model generation to visualization in highly immersive environments and conclude with a set of general recommendations for earthquake visualization.

Finite-fault earthquake source inversions infer the (time-dependent) displacement on the rupture surface from geophysical data. The resulting earthquake source models document the complexity of the rupture process. However, multiple source models for the same earthquake, obtained by different research teams, often exhibit remarkable dissimilarities. To address the uncertainties in earthquake-source inversion methods and to understand strengths and weaknesses of the various approaches used, the Source Inversion Validation (SIV) project conducts a set of forward-modeling exercises and inversion benchmarks. In this article, we describe the SIV strategy, the initial benchmarks, and current SIV results. Furthermore, we apply statistical tools for quantitative waveform comparison and for investigating source-model (dis)similarities that enable us to rank the solutions, and to identify particularly promising source inversion approaches. All SIV exercises (with related data and descriptions) and statistical comparison tools are available via an online collaboration platform, and we encourage source modelers to use the SIV benchmarks for developing and testing new methods. We envision that the SIV efforts will lead to new developments for tackling the earthquake-source imaging problem.