“…The velocity structure of the Osaka basin has been investigated extensively using geophysical and geological techniques such as gravity anomaly measurements (e.g., Nakagawa et al 1991;Inoue et al 1998), refraction and reflection surveys (e.g., Toriumi et al 1990; Kagawa et al 1990;Horike et al 1996), offshore seismic air gun reflection surveys (e.g., Iwasaki et al 1994;Iwabuchi et al 2000;Ito et al 2001), boring explorations (e.g., Ikebe et al 1970;Yoshikawa et al 1998;Inoue et al 2013), microtremor measurements (e.g., Kagawa et al 1998;Uebayashi 2003;Yoshimi 2012;Minami et al 2014), and strong motion observations (e.g., Hatayama et al 1995;Toki et al 1995). Based on the results obtained using these techniques and ground motion simulations for observed moderate events, three-dimensional velocity structure models of the Osaka basin have Open Access *Correspondence: k-asano@egmdpri01.dpri.kyoto-u.ac.jp 1 Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan Full list of author information is available at the end of the article been developed and improved over several decades (e.g., Kagawa et al 1993Kagawa et al , 2004Horikawa et al 2003;Iwata et al 2008;Iwaki and Iwata 2011;Sekiguchi et al 2013). Although many types of surveys have been conducted, more direct information and validation on the S-wave velocity structure is still necessary to improve the velocity structure model because the available constraints from those surveys are not distributed uniformly over the basin.…”