An article by the NZ Herald reports that recommendations for slope monitoring and early warning made by a geotechnical consulting firm in a report 2 years before the initial failure were not adopted by Auckland Transport. The Birkenhead landslide initially took out 25 parking spaces in a retail area in October of 2017, and a larger landslide in November of the same year took out a micropile or other drill rig working to stabilize the site. Local officials defended the decision, indicating that they instead opted for regular site visits and visual observation of cracks noted in the report. The initial recommendations by GHD Engineers included the monitoring as a minimum, and also recommended several stabilization options in the range of $500k. The current estimates to repair the landslide are $14M to $24M.
Geology.com pointed out a very nice PDF version of a Power Point presentation by the North Carolina Geologic Survey on their landslide hazard mapping efforts in western North Carolina. The presentation was dated August 1 of last year. The NCGS also has their landslide mapping products available for download, and those so inclined can download the GIS data sets as well. (Photo by NCGS)