Surface ruptures associated with the 1992 Landers earthquake (Mw 7.3) damaged structures in the Landers, California area. Six trenches were excavated adjacent to three structures (two condemned single family residences and one steel transmission tower) that were damaged by direct fault displacement. The pattern, style, and magnitudes of deformation were mapped in detail immediately after the earthquake and during our investigations. The pattern of surface ruptures consisted of left-stepping right-lateral displacements with local vertical components within wide zones of distributed shear that contained narrower faults. The trenches generally exposed poorly stratified granular materials in which faults that were mapped on the surface were difficult to recognize in the trench Techniques were used such as trench wall curing, brushing, blowing with a leaf blower, and an ultraviolet lamp at night to locate and enhance stratigraphy, fractures and offsets. The subsurface structure generally exhibited an upward splaying pattern within a complex zone of fractures at all three sites. The foundations of the two condemned residences consisted of unreinforced concrete slab-on-grade construction with continuous perimeter footings and the steel transmission tower consisted of four steel tripod earth-backfilled footings. At one residence, the fault expressed primarily strike-slip motion. Cracks in the slab foundation first opened in tension and then slipped laterally. The slip was distributed over several fractures and some dextral shear was accommodated by slab rotation. At the other residence, some of the deformation concentrated on preexisting cracks which opened in tension and accommodated lateral slip. Slab rotation was also significant. Up to one foot of vertical faulting was expressed primarily as tilting of the slab. The transmission tower foundation was offset nearly 2.7 m right-laterally in a concentrated narrower fault, producing rotation of the tower itself. This fault formed the east side of a 70-m-wide zone of distributed shear. Several conclusions can be drawn from the above observations. First, trench logging techniques and interpretations play a key role in conclusions for fault history. Second, the upward splaying pattern of faulting in the subsurface of all trenches indicates that unconsolidated alluvium tends to spread out the width of surface rupture. Third, unreinforced concrete slabs deformed brittlely, and preexisting cracks and cold joints localized slip in the slab. Fourth, where a vertical component was present, deformation was expressed primarily by tilting of the broken slab pieces. Fifth, some movements produced rotation of the slab rather than brittle slip. Sixth, observations suggested decoupling of the foundation underlain by Visqueen from the underlying ground movements, and horizontal shearing of sands below the foundation in an area apparently not underlain by Visqueen. These observations lead us to believe that cm adequately reinforced slab with poor coupling to the ground may avoid breakage thereby reducing the level of damage and increasing structural safety.