Living in Lyttelton – If It Rains for Three Days or More There Will Be Slips
Because of the steep slopes, loess and under runners. I was unfamiliar with the last two before I moved to New Zealand.
From A New Zealand Diary:
Lyttelton, being located on the steep sides of an extinct volcano, doesn't suffer extensive flooding, but it is prone to landslides, which Kiwis like to call 'slips'.