Maori, renters and those aged under 40 are most at risk following a disaster.
The figures come from a new Colmar-Brunton poll which asked 1000 people about their disaster-preparedness.
It found 87 percent of Maori are not fully prepared, compared with 74 percent of all New Zealanders.
Eighty-three percent of those aged under forty and 80 percent who do not own their own home are also under prepared.
Being prepared includes having goods such as water, food and a torch handy.
Around one in five New Zealanders think it's unlikely they will ever be in a disaster and this belief is a strong barrier to them taking steps to prepare.
Minister of Civil Defence Kris Faafoi said he was concerned at the number of unprepared New Zealanders.
"Following the Canterbury sequence of earthquakes, we saw a spike in people getting prepared, then it dwindled over time. We're seeing the same pattern emerge following the Kaikōura earthquake which suggests complacency is creeping in again."
He said too many were putting it in the "too hard" basket.
"Getting prepared doesn't need to be a difficult or costly task. The most important thing you can do is have a five minute conversation with your family, whanau or flatmates, and make a plan."
The poll showed people's disaster preparedness spiked after the Christchurch and Kaikōura earthquakes, but then went down again.
The percentage of New Zealanders who knew what to do during an earthquake had also dropped since last year.
Sixty-seven percent of people knew at least one correct action to take compared with 73 percent last year.
Correct actions included hiding under a table or desk.
These figures contrast with the 78 percent of people who said it was easy to prepare for an emergency and 79 percent who said they knew a lot about preparing.
One improvement was for people living near the coast - 89 percent knew to move inland or to higher ground compared with 81 percent in 2017.