A procedure is presented for modeling and investigating the pre and post-failure geotechnical characteristics of soils affected by strong earthquakes. Using a new method of dynamic numerical analysis and an experimental program aimed at understanding the post-failure behavior of such soils, it is shown that the resultant 0.74 factor of safety, 30 - 40 m failure elevation, critical failure plane and zero effective stress values are consistent with field work findings and observations. Compared to another method of stability analysis used in this research only the dynamic analysis provided the exact location of the most critical sliding surface. Laboratory undrained shear results on strongly weathered soils from the affected slopes show that after failure, generated excess pore water pressure was equal to the applied normal stress on the soils indicating that the soils liquefied and that they must have traveled down slope at considerable speed which correspond to the destruction and disruptions witnessed.