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Toward Utilization of Physics-based Simulations in Seismic Hazard Assessment: Insights From Japan Experiences

Description: 

Ground-motion simulations that incorporate the fault and 3D velocity models, often referred to as “physics-based” simulations (PBS), predict ground motion for a specific earthquake scenario by numerically modelling fault rupture and wave propagation processes in time and space. In this presentation, we discuss the benefits and challenges in two primary ways to utilize PBS in seismic hazard assessment from the experiences of the National Seismic Hazard Maps for Japan. One way is to use PBS data as a supplement to ground-motion observation data in the framework of probabilistic seismic hazard assessment (PSHA). While comprehensive and well-maintained databases of ground-motion observation data have contributed to the development of GMMs in the world, GMMs exhibit large uncertainties due to lack of data for large-magnitude earthquakes and distinctive strong-motion recordings that reflect specific conditions such as near fault effects and basin effects. The other way is to use a set of PBS time-series waveform data for detailed seismic risk assessment at specific sites/area and for specific structures for an anticipated earthquake. In both ways, PBS provides ground-motion prediction given the simulation method and input parameters for future scenarios. In order to utilize PBS data in seismic hazard assessment, the limitations and uncertainties of PBS must be investigated in terms of i) simulation method of fault rupture and wave propagation, ii) 3D velocity model, and iii) input parameter ranges.

The National Seismic Hazard Maps for Japan contains simulation data for scenario shaking maps for > 1000 scenarios for major inland active faults. The rupture model follows the kinematic rupture characterization method based on Irikura and Miyake (2011). Broadband ground-motion time-histories are computed by 3D finite-difference simulations at long periods (> 1 s) and 1D stochastic synthesis at short periods (< 1 s) based on the 3D velocity model (J-SHIS model). We review the validation studies of the methods and the models, and discuss the challenges in identifying the uncertainties associated with the simulations.

Session: Challenges and Opportunities in Constraining Ground-motion Models from Physics-based Ground-motion Simulations - I

Type: Oral

Date: 4/17/2025

Presentation Time: 08:15 AM (local time)

Presenting Author: Asako

Student Presenter: No

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