Slope failures associated with the 1988 Saguenay earthquake, Quebec, Canada

Abstract

Nine case records of slope failure during the Saguenay earthquake are documented, including five in granular embankments, two in natural slopes in granular material with small embankments at the top, and two in sensitive clay. The bedrock motion during the earthquake is well documented; each failure is related to the most probable bedrock motion at the site (0.05 to 0.15 g). For the seven cases of failure in granular slopes, the reserve of stability under static conditions was relatively low before the earthquake, and only a small additional undrained loading was necessary to develop failure. Two slope failures occurred in extrasensitive clay deposits containing no visible lens or layer of silt or sand. Silty or sandy materials have been identified only at the clay–till contact. It is believed that in at least one of the sites a portion of the failure surface developed at the inclined clay–till contact. Key words : slope failure, earthquake, sensitive clays, embankment fill, stability, granular material.