Christchurch is preparing for the fourth memorial of the February 22 earthquake.

Sunday will mark four years since the 6.3 magnitude quake killed 185 people, and changed life forever in Canterbury.

Christchurch City Council spokesman Duncan Sandeman says once again the civic memorial service will be held on the Archery Lawn of the Botanic Gardens at midday.

"The names of those who died in the Earth will be read out, there will be a a wreath laying ceremony by official dignitaries and at 12.51pm there'll be a minute silence."