The catastrophic effects of earthquakes that frequently occur on the West coast of South America motivated this research. Ecuador, in particular, is located in a zone of high seismic activity due to processes of tectonic plate subduction that give rise to earthquakes of great magnitude, such as the seismic motion of magnitude Mw equal 7.8 that struck the coastal city of Pedernales on April 16 2016, producing great damages to the infrastructure and losses of human lives. The present research aims to study the dynamic behavior of two types of earth structures: a slope composed of colluvial soil of approximately 70 m height and the Mazar rockfill dam constructed for hydroelectric generation. The Mazar dam, according to its height (166 m), is classified as a large dam by the International Commission on Large Dams (ICOLD) and qualified by the Ecuadorian Construction Standard (NEC, 2014) as a structure of essential importance, with mandatory analysis of seismic performance under two seismic design ground motions: the operating basis earthquake (OBE) and the maximum credible earthquake (MCE) with return periods of 475 years and 2500 years, respectively. The analyses carried out in this work included the generation of the OBE and MCE earthquakes, investigation of static and pseudo static stability of slopes, determination of permanent displacements using simplified analytical methods and numerical simulations. Significant differences in the maximum permanent displacements were observed using analytical and numerical approaches.