This paper presents a survey of seven unique case-history sites, along with a review of the techniques used in analyses of downhole seismic records. These techniques include correlation and spectral analyses, stress-strain imaging, and system identification procedures. Spectral techniques were used to evaluate shear wave propagation characteristics, variation of shear wave velocity with depth, and site resonant frequencies and modal configurations. Stress-strain imaging is a newly developed technique used to evaluate seismic shear stress-strain histories directly from recorded downhole accelerations. System identification procedures were employed to estimate soil stiffness and damping
parameters, and to calibrate computational models of seismic site response. These various studies provided valuable insights and documented: (1) vertical wave propagation and site resonance mechanisms, (2) characteristics of site amplification for soft and stiff soil formations, and (3) cyclic soil behavior during liquefaction and associated loss of stiffness and strength. At present, downhole-array data offer a most effective means for calibration and verification of predictive computational tools of site seismic response.