Isoseismal Map for a Scenario Earthquake on the Causative Fault of 2016 Gyeongju Earthquake

The stochastic method is applied to simulate strong ground motions at 100 seismic stations in South Korea by a scenario earthquake on the causative fault of 2016 Gyeongju earthquake and its isoseimal map is proposed. Input parameters are established based on what have been revealed so far for the causative fault of the Gyeongju earthquake, and the ratio in response spectra between observed and simulated strong ground motions is assumed to be an adjustment factor. Strong ground motions by a scenario earthquake on the causative fault of Gyeongju earthquake with moment magnitude 6.5 are simulated assuming the ratio of its fault length to width to be 2:1 and aforementioned adjustment factor. The results are similar to existing those of applying the empirical Greens function method to 11 seismic stations, and the calculations confirm the applicabiliy of strong ground motion simulations based on the relatively small bias in response spectra between observed and simulated strong ground motions. Although actual site response factors of seismic stations and so on should be supplemented later, the simulated strong ground motion data can be used as not only input data for developing ground motion prediction equations, but also input data for calculating design response spectra of major facilities in South Korea.