Roughness, Rupture, Radiation and High-Frequency Seismic Waves

Session: What Can We Infer About the Earthquake Source Through Analyses of Strong Ground Motion?
Type: Oral
Date: 4/29/2020
Time: 05:00 PM
Room: 115
Description: 

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 this presentation, I will discuss recent work to understand effects of 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 naturally generate realistic synthetic seismogram that can be used for engineering applications. I will also show how variations in rupture speed are driven by specific patterns in fault-roughness distribution, that is, geometrical features in fault surfaces constitute high-frequency seismic energy sources. I also show that in kinematic simulations, the geometrical complexity of the fault does not need to be parameterized if the spatial variations in rupture speed are correctly modelled.

Presenting Author: Paul Martin Mai

Authors