Landslides are one of the most common natural hazards all over the world. In mountainous northern Algeria, the rainy winter climate triggers or reactivates a variety of instabilities, causing major structural and infrastructure damage in several wilayas (provinces). The activation of these instabilities is often related to exceptional weather (such as heavy rain or snow). Tizi-Ouzou region, located in the Mediterranean part of Algeria, is one of the zones most affected by this hazard. Over 50 instabilities, each spanning an area of more than 2 ha, have been identified in various cities and villages of this region.

This paper summarizes a study of a landslide that affects Azazga city, located at 20 km east of Tizi-Ouzou city and 117 km east of the capital Algiers. The unstable zone covers an area greater than 260 ha and affects vital structures, such as the regional hospital and polyclinic. Since the winter of 2012, this ground movement has been experiencing significant activity phases related principally to climate effects, such as a reactivation in March 2012 caused by a major snow cover, and a reactivation in 2014 caused by heavy rains. The objective of this paper is to determine the landslide reactivation threshold in terms of the average monthly rainfall and exceptional rainfall using the software PLAXIS2D.