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Development of Stochastic Ground-motion Models for a Reference Rock Condition in South Korea

Description: 

Ground motion models (GMMs) play a crucial role in seismic hazard analyses. Developing empirical GMMs is impractical in South Korea due to the lack of strong-motion earthquake records, leading to the use of alternative approaches such as stochastic simulations. Meanwhile, in the U.S. nuclear industry, site-specific ground-motion response spectra (GMRS) are developed in accordance with U.S. NRC Regulatory Guide 1.208 by defining a reference rock condition for the Central and Eastern United States and developing GMMs applicable to that reference rock.

In this study, GMMs are developed using stochastic simulations (Boore, 2003) for a reference rock condition in South Korea, defined in a separate study (Noh, 2024) as a shear-wave velocity of 2.5 km/s. For the simulations, site characteristics of the reference rock condition, including the high-frequency spectral decay parameter (κ) and site amplification functions, were investigated using a suite of accelerometer stations across South Korea. The traditional method of Anderson and Hough (1984) and the square-root-impedance method proposed by Boore and Joyner (1997) were applied for κ estimation and site response analysis, respectively. The derived GMMs cover moment magnitudes from 3.0 to 8.0 and distances from 10 to 500 km. Median GMMs are provided together with aleatory standard deviations. The GMMs are compared with observed ground motions from available earthquake records for moment magnitudes ranging from 3.0 to 5.5. This study presents a novel set of ground-motion models for a reference rock condition in South Korea. The GMMs incorporate reference rock characteristics in South Korea and explicitly account for associated aleatory uncertainties. These results provide key input for probabilistic seismic hazard analysis (PSHA) in the development of the GMRS for nuclear facilities in South Korea.

Session: Advancing Seismic Hazard and Risk Assessment through Multi-Disciplinary Approaches - I

Type: Oral

Date: 4/15/2026

Presentation Time: 11:30 AM (local time)

Presenting Author: Seonjeong Park

Student Presenter: No

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