Simulation of strong ground motions from 2016 Kumamoto (Mw 7.1), Japan, earthquake using modified hybrid technique

In 2016, an earthquake with a magnitude of Mw 7.1 occurred at 01:25 JST (16:25 UTC on April 15, 2016) on April 16, 2016, popularly known as the Kumamoto, Japan, earthquake, following the earthquake with a magnitude of Mw 6.1 that occurred on April 14, 2016, at 21:26 JST (12:26 UTC on April 14, 2016). This was one of the largest earthquakes to occur since the deployment of the Kyoshin network (K-NET) and Kiban-Kyoshin network (KiK-net) after the 1995 Hyogo-ken Nanbu event. In the present study, the 2016 Kumamoto, Japan, earthquake has been simulated using the modified hybrid technique. Out of 53 recorded stations located in the Kyushu region, simulations have been performed at 28 recordings using the modified hybrid technique. Earlier, this technique was independent of site response functions and the high-frequency decay parameter (kappa (κ)). In this study, these two important factors have been introduced. With the help of the selected model, simulated accelerograms and their corresponding Fourier and response spectra for each site have been generated. Later, parameters like duration, PGA, Fourier, and response spectra have been compared with the observed ones at different stations. It was found that the observed PGA at the closest station, KMMH16, located at an epicentral distance of 7 km, was 1155 cm/s2, while the simulated value was 1217 cm/s2. Other frequency domain parameters are very well matched with the observed data at other sites. These studies can help in seismic hazard analysis and in designing earthquake-resistant buildings.