<p>Ground response analysis and determination of site-specific ground motion parameters are necessary for evaluating seismic loads to enable sustainable design of aboveground and underground structures, particularly in deep overburden sites. This study investigates the influence of bedrock interface conditions and depth of soil deposits on obtained site-specific ground motion parameters. Employing the one-dimensional seismic response analysis program SOILQUAKE, the ground responses of five representative soil profiles and 1 050 case studies are calculated considering three different site models of seismic input interfaces. The analysis employs the actual bedrock interface with a shear wave velocity of 760 m/s as the reference input bedrock interface. The results illustrate that the selection of the bedrock interface condition significantly affects the seismic response on the ground surface of deep overburden sites. Specifically, the ground surface acceleration response spectra at longer periods are notably smaller compared to those at the actual bedrock site. This may present a challenge for designing long-period high-rise buildings situated in deep overburden sites. It is recommended to select a seismic input bedrock interface closely approximating the actual bedrock depth when conducting seismic response analyses for deep overburden sites.</p>