Imaging Hierarchical Seismic Sources by Seismic Waves

Session: What Can We Infer About the Earthquake Source Through Analyses of Strong Ground Motion?
Type: Oral
Date: 4/29/2020
Time: 04:30 PM
Room: 115
Description: 

Earthquakes are almost scale-free phenomena, which start from very tiny rupture and grow into giant events with very small probabilities. The prediction of the final size of each event is very difficult because of inherent randomness of rupture process. However, rupture processes are not completely random, but restricted by the preexisting fault structure, which is also almost scale-free. Therefore, in cases of mature fault systems like a subduction interface, the distribution of interplate earthquakes is fairly stable, as clearly demonstrated by many families of repeating earthquakes. Nevertheless, even repeating earthquakes suggest some complex structure (e.g., Uchida et al., 2012) and two events starting at almost the same place may grow into different-sized events, as demonstrated by empirical source imaging with seismic waveforms (Okuda and Ide, 2018). An extensive comparison of initial seismic waves between different-sized earthquakes found many event pairs with identical onsets, only for subduction-type earthquakes (Ide, 2019). These lines of evidence support the idea of hierarchical source models with nested source units which have been developed by long-term deformation and exist for long-time. Such information may not be directly useful in practical disaster prevention, but helps to assess scenarios for future large earthquakes and understand the generation process of strong ground motion. In this presentation, I review our recent studies about hierarchical source structure with new examples of source imaging and initial wave comparison.

Presenting Author: Satoshi Ide

Authors