LANDSLIDE MONITORING AND MOVEMENT HISTORY OF THE SALMON FALLS LANDSLIDE, SOUTH-CENTRAL IDAHO

摘要

The Salmon Falls landslide is a 0.25 km~2 active, deep-seated, canyon rim rock slide located in a relatively remote area of south-central Idaho. Rapid movement of the landslide was first reported in 1999.The landslide activity has created natural dams in Salmon Falls Creek, a 0.85-8.5 m~3/sec tributary to the Snake River, producing potential hazards to life and property downstream. Total station surveying, high-resolution remote sensing imagery, GPS, and geological field studies reveal the nature and magnitude of the landslide motion. This study has constrained an earlier initiation of significant movement prior to 1998 through image change detection analysis. Monitoring of the landslide indicates that velocities were highest, ca. 200 cm/yr when surveying was first initiated in 2001, and since then have steadily decreased to ca. 15 cm/yr. Given the current rate of motion of the landslide and pronounced dam armoring, flood hazards associated with dam failure appear minimal.