This lecture presents current knowledge about the application of the limit-equilibrium method and the specification
of pseudo static equivalent seismic forces to assess the stability of slopes threatened by variable groundwater,
earthquakes, or both. The paper presents useful slope-stability results for long slopes, circular failures surfaces,
and compound failure slip surfaces. Key issues reviewed in the paper are the specification of shear strength of
soils, the effect of liquefaction and lay softening on seismic slope stability. Real world examples of slope stability are presented,
in particular, the Oso landslide that killed 43 people in 2014 in the state of Washington. It is shown in the lecture that
landslide occurrence is influenced by short term stresses but also by conditions for failure that have dynamic structural controls
that act over millennia. A recent paper on the subject matter will be distributed to attendants free of charge.
Hugo A. Loaiciga, Ph.D., P.E., is professor of Hydrology at the University of California, Santa Barbara. He has
been working on the subject of groundwater and landslide activity since 1990, both as researcher and consultant.
Dr. Loaiciga has authored 211 scientific/technical works and has consulted for various agencies nationally and
Address: 7 Hutton Dr., Santa Ana, CA
Meal: Regular or Vegetarian
Cost: $30 (member),