Other infrastructure damage
- Collapsed, broken, and subsided walls
- In the Port Hills, especially Lyttelton, moving land, collapsed cliffs, and rockfall caused severe damage to retaining walls. Some have collapsed, subsided, or just broken up in parts. Some have been weakened and need to be stabilised with temporary supports.
- Broken stopbanks
- Some stopbanks by the Avon River settled and cracked so that a spring tide could flood the land. Contaminated tidal water came onto roads through broken drainage pipes. Banks and pipes failed because the ground moved toward the river and settled in a lower position than it had been.
- Weakened stopbanks
- All stopbanks by the Avon River were at least weakened by the shaking. The stopbanks need to remain raised, firm, and uncracked to function effectively.
- More stopbanks needed
- We now need another 4 kilometres of stopbanks along the Avon River because the surrounding land is lower than before the earthquakes.