There is much uncertainty in seismic earth pressures for basement wall design and retaining wall design in clay soil. The research presented herein uses a scale model testing platform on a 1g shake table to measure the distribution and magnitude of seismic earth pressures for the prototype soil conditions of San Francisco Young Bay Mud (YBM). Similitude scaling of the dynamic soil properties, the wall dimensions, and the input time histories (among other variables) affords accurate modeling of the prototype scale wall. For basement conditions, inertial soil structure interaction (SSI) effects are included in the experiments. Care is taken to properly mimic static lateral stress conditions of the walls to achieve active or at-rest conditions for the respective wall designs prior to shaking. Results for a wall of prototype 3m height experiencing a large ground motion is shown and compared to current earth pressure design recommendations.