This research is on cap type soil plasticity models derived from experience in constitutive modeling of geological materials and will help answer the urgent need to develop rational methods for the prediction of earthquake induced slope failures. The research concentrates on the development of a cap model specialized for seismic analysis. The resulting simplified model should be adequate for dynamic slope stability analysis while, at the same time, easily usable by a broad community of engineers. The research provides improved insight into conventional methods of seismic slope stability analysis and into the design of countermeasures to mitigate the damage due to slope failures. The final results will involve a computational methodology that will be easily incorporated into the practice using the computer software. This research is being conducted under the Small Business Innovation Research program as Phase I research.