After the 1995 Hyogoken-Nanbu earthquake, NIED (National Research Institute for Earth Science and Disaster Prevention) installed the K-NET that uniformly covers all Japan with more than one thousand strong-motion accelerometers on the ground surface. In addition to the K-NET, NIED constructed an uphole/downhole observation network, KiK-net, with approximately 669 stations. Each KiK-net station has a borehole of 100 m or more in depth and strong-motion seismographs have been installed both on the ground surface and at the bottom of the boreholes. The velocity profiles and geological information as well as the observed records are widely accessible on the website.