Martin Mai, King Abdullah University of Science and Technology (KAUST)
Faculty Host: Yuri Fialko
Geological faults comprise large-scale segmentation and small-scale roughness that govern earthquake processes and associated seismic radiation. Standard techniques for seismic hazard assessment for such faults (or fault systems) are insufficient, but numerical simulations for multi-scale geometrical complex faults help to shed light on rupture dynamics and seismic radiation of such systems.
In my presentation, I will discuss recent work to understand effects of large-scale segmentation and small-scale roughness on rupture evolution and near-source shaking. Using numerical simulations, we find that rupture incoherence due to fault roughness leads to high-frequency spectral decay consistent with observations. Waveform characteristics and comparisons with empirical ground-motion relations show that rough-fault rupture simulations generate realistic synthetic seismogram that can be used for engineering applications. We also show that for segmented faults, the spatial distribution of the regional stress is of critical importance as it determines the initial stress on the fault system. Similarly, the rupture nucleation point has significant impact on the resulting rupture process and earthquake size. Consequently, seismic hazard assessment for such fault systems must include fundamental earthquake physics to capture the possible near-source shaking levels of future earthquakes.
Examples will be shown for scenario earthquakes in the Marmara Sea, where large-magnitude events are expected that may rupture two or more fault segments, and for the Gulf of Aqaba, a region of increased infrastructural developments near a poorly studied transtensional fault system that has generated large earthquakes in the past.