Fourth Avenue Landslide during 1964 Alaskan Earthquake

Abstract

This paper presents a reevaluation of the Fourth Avenue landslide in Anchorage that occurred during the 1964 Alaskan earthquake. Laboratory constant volume ring shear and field vane shear tests were used to measure the undrained peak and residual shear strength of the Bootlegger Cove clay. The results of these tests are presented and compared to back-calculated shear strengths of the Bootlegger Cove clay. The comparison shows that slide blocks that moved less than 0.15 m mobilized at least 80 of the undrained peak shear strength. Slide blocks that moved between 0.15 to 2.5 m mobilized an undrained shear strength between the peak and residual shear strengths. Slide blocks that displaced more than 2.5 m mobilized the undrained residual strength.