This lecture focuses solely on liquefaction initiation. The factor of safety against liquefaction triggering is introduced, and the cyclic resistance ratio and cyclic stress ratio are explained. Steps to perform a simplified liquefaction triggering analysis are provided. Please combine this lecture with the Idriss and Boulanger (2010) technical report: https://faculty.engineering.ucdavis.edu/boulanger/wp-content/uploads/sites/71/2014/09/Idriss_Boulanger_SPT_Liquefaction_CGM-10-02.pdf