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Probabilistic seismic hazard analysis (PSHA) generally requires the identification of line sources (active faults) and area sources where seismicity parameters must be determined. It is not easy to identify seismic… Click to show full abstract
Probabilistic seismic hazard analysis (PSHA) generally requires the identification of line sources (active faults) and area sources where seismicity parameters must be determined. It is not easy to identify seismic sources and to estimate seismicity parameters for sources in the intraplate region. We perform an alternative PSHA with a synthetic earthquake catalog, which does not require the delineation of seismic sources. A synthetic catalog of the Korean Peninsula for 500,000 years is constructed by simulating earthquakes using the Monte Carlo method in such a way that an earthquake is randomly selected from the observed earthquake catalog, its epicenter is perturbed by a normally distributed random number, and a magnitude is assigned to the simulated event with a random value generated based on the Gutenberg-Richter magnitude-frequency relation with specified minimum and maximum magnitudes. The seismicity of the Korean Peninsula is thoroughly investigated for estimation of parameters required for synthesizing the catalog. The SMSIM computer program is used to simulate ground motions at sites instead of estimating the ground motion prediction equation. Two sites are chosen for PSHA; the one is the Seoul City Hall site (Seoul site), a densely populated metropolitan site, and the other is the Gyeongju City Hall site (Gyeongju site) close to the epicenter of the ML 5.8 earthquake on 12 September 2016. Seismic hazard curve, uniform hazard spectra (UHSs), and deaggregation of hazard for two sites are presented. The mean return periods for 0.1, 0.2, and 0.3 g at the Seoul site appears to be 1640, 6170, and 17650 years, respectively while those at the Gyeongju site appears to be 327, 1197, and 3548 years, respectively. The mean return periods for the Seoul site are around five times longer than those for the Gyeongju site, and this fact implies that the seismic hazard level of the Gyeongju site is considerably higher than that of the Seoul site. UHSs for 10% and 2% probabilities of exceedance over 50 years are constructed at both sites. The spectra show peak amplifications around the 0.05-s period.