Natural hazards
Cliff erosion
East Coast Cliff Erosion
The coastal cliffs in Auckland are slowly eroding. Cliffs on Aucklands East Coast are most susceptible, eroding at a rate of approximately 2-6m per century. This has been the case for the past 6-10,000 years.
West Coast Cliff Erosion
Erosion along West coast is 2 orders of magnitude smaller and is considered almost negligible, except near Awhitu.
Where will cliff failure occur?
Where failure occurs is dependant upon many local factors, including geological conditions, as well as land use and vegetation management practices.
Cliff failure can occur in a number of ways from slumping to large block failures. An example of the extreme end of the scale is a large cliff failure event which occurred near Rothesay Bay within the last 10 000 years and is in the order of 400 m in, by 350 m wide, by approximately 20 m deep. However, retreats of probably 10 - 15 m are likely to be common.
Cliff erosion and failure puts these things at risk:
- residential property and homes
- human life
- land transport (road could take up to several days to clear)
- infrastructure e.g. sewerage, water supply, or gas pipes
- esplanade reserves and public access.
