Damage due to Northridge Earthquake Induced Movement of Landslide Debris

A case study of Northridge Earthquake induced movement of landslide debris is presented. Based on the width of the observed cracks, the estimated earthquake-induced lateral movement of the landslide debris was 6–12 mm (0.25–0.5 in.). Associated with the lateral movement of the landslide debris, there was a differential movement of 102 mm (4.0 in.) of the house foundation and 69 mm (2.7 in.) for the pool. There was severe damage to the house and the appurtenant structures due to the landslide debris movement. Inclinometer readings indicate that the landslide debris continued to move after the earthquake. Because the house was built in 1956, there probably was no geologic investigation which would have detected the unstable geologic condition at the site.