Ground Motion Characterization for Vertical Ground Motions in Turkey—Part 1: V/H Ratio Ground Motion Models

Two approaches are used to develop the vertical design spectra in probabilistic seismic hazard assessment (PSHA): (i) performing PSHA for the vertical component using vertical ground motion models (GMMs), and (ii) utilizing the V/H ratio GMMs to scale the horizontal spectrum during or after the hazard calculations for the horizontal component. This study intends to develop a new framework for building a vertical ground motion logic tree that combines both vertical and V/H ratio GMMs in the PSHA analysis. For this purpose, the Turkish strong motion database (TSMD) (Akkar et al. in Journal of Seismology 14(3): 457–479, ) is updated with recordings from earthquakes that occurred between 2008 and 2015, including the M_w = 6.1 Elazığ and M_w = 7.2 Van earthquakes. The updated TSMD contains 2698 recordings, with the earthquake metadata, source-to-site distance metrics for the recordings, measured shear wave velocity profiles for the recording stations, and spectral accelerations for horizontal and vertical components. Four candidate V/H ratio GMMs (proposed by Gülerce and Abrahamson in Earthquake Spectra 27(4): 1023–1047, ; Gülerce and Akyuz in Seismological Research Letters 84(4): 678–687, ; Akkar et al. in Bulletin of Earthquake Engineering 12(1): 517–547, ; Bozorgnia and Campbell in Earthquake Spectra, 32(2): 951–978, ) are selected, and the model predictions are compared with the actual data in the updated TSMD using the analysis of the residuals and data-driven techniques. Analysis results showed that the median predictions of the V/H ratio GMMs proposed by Gülerce and Akyuz (), Akkar et al. (), and Bozorgnia and Campbell () are compatible with the V/H ratios in the Turkish strong motion dataset. The findings of this study and the compatibility analysis of the vertical GMMs with the updated TSMD are combined in the accompanying manuscript (Gülerce et al. in Pure and Applied Geopyhsics, 2019, submitted) to provide the complete framework of ground motion characterization for vertical ground motion component.