OpenAmp: An Open-Source Site Amplification Database to Unlock the Potential of Machine Learning

OpenAmp is an open-source, consistently curated, high-quality database of earthquake site amplification functions derived from instrumental recordings, accompanied by a comprehensive suite of site metadata, for 1,742 K-NET and KiK-net strong-motion recording sites in Japan. The site metadata builds upon the site database of Zhu et al. (2021) and introduces several new parameters, including the site-specific spectral decay parameter (κ0), the standard deviation of the horizontal-to-vertical spectral ratio of earthquake recordings (σHV), and site dimensionality index (I1D3D). A distinctive feature of OpenAmp is the inclusion, for the first time, of a diverse set of vector-based parameters and proxies, including quarter-wavelength velocity (Vs,qwl), and frequency- and scale-dependent topographic metrics. The (linear) site amplification functions are derived from weak-motion recordings using a generalized inversion technique in the Fourier domain.File description:‘OpenAmp_v1.0_HumanReadable.xlsx’: OpenAmp database interpretable by human experts;‘OpenAmp_v1.0_MachineReadable.csv’: OpenAmp database directly readable by machines;‘VariableDescriptions.xlsx’: Definition of variables in ‘OpenAmp_v1.0_MachineReadable.csv’;‘Plot_Amp.zip’: Plots of amplification functions in comparison to those of Nakano et al. (2015);‘Plot_Vs(z)_borehole_JSHIS_JIVSM.zip’: Plots of shear-wave velocity versus depth profiles from downhole measurements, as well as extracted from J-SHIS (v3.2) and JIVSM (v1.0) 3D regional velocity models;‘Plot_Vsqwl.zip’: Plots of quarter-wave length velocities computed from the shear-wave velocity profiles in ‘Plot_Vs(z)_borehole_JSHIS_JIVSM.zip’.OpenAmp will be updated periodically. Users should check the Figshare record for the latest version.Citations:Zhu, C., Kwak, D.Y., Pilz, M., Haendel, A., Xie, J., Kawase, H., Cotton, F. (2025). OpenAmp: An Open-Source Site Amplification Database to Unlock the Potential of Machine Learning. https://doi.org/10.25398/rd.northumbria.29649008Zhu, C., Weatherill, G., Cotton, F., Pilz, M., Kwak, D.Y., Kawase, H. (2021). An open-source site database of strong-motion stations in Japan: K-NET and KiK-net (v1.0.0). Earthq. Spectra 37, 2126-2149. https://doi.org/10.1177/8755293020988028