The main highway south of Kaikoura is to remain closed for three more weeks.
State Highway 1 has been shut since Easter following a slip near Rosy Morn, between Peketa and Goose Bay.
The New Zealand Transport Agency (NZTA) had hoped the route would reopen next week, but have been forced to reassess the situation after further movement overnight.
The new slip will be cleared next week.
NZTA earthquake recovery manager Steve Mutton told Stuff there are a number of sites between Peketa and the new slip which required "a fortnight of stabilisation and repair work".
He also said the highway would "be prone to short-term closures for some time given the tension cracks along the cliffs created by the earthquakes, which are prone to collapse with rain and stormy weather".
Kaikoura can still be accessed by Inland Rd via Waiau and Mt Lyford.