Mud Creek Landslide
A combination of excessive precipitation, tectonically abused rocks and overall weak strength of the Franciscan Formation and over steepened slopes from erosion led to the collapse of about 70 acres of rock. The landslide not only buried Highway 1 new landslide toe extended out into the Pacific Ocean. A CSM program was started, using ground-based InSAR, after the initial collapse. The proactive monitoring project successfully reduced risk from rockfall and smaller residual failures that continued to occur for several months.
The Ferguson Rock Slide has a long history of repeated rockfall and larger failures. New repair designs required drilling to locate the depth to competent rock to establish a strong supporting foundation. Prior to drilling operations, the client requested a monitoring program be established before starting work. We proposed a CSM program that provided daily reports and the communication of any progressive movement events that presented a threat to the drillers. A communication chain of command and specific levels of risk were documented in a site-specific TARP.
An open-pit mine slope more than 2,000 feet in height, which had not been actively mined in over 6-years had only exhibited moments of slow creep before failing. The 5-million ton mine failure changed to a progressive event during the second week of October 2012. Ground-based InSAR identified the beginning of the acceleration event over a week in advance of the failure. Although inverse velocity data was beginning to exhibit a gradual approach to linearity, it was not until linearity became more distinct and confidence levels increased that a successful prediction 3-days in advance of the actual failure was announced site-wide.