Mr Key said New Zealanders should remember those who lost their lives on February 22.
"They are faces of a Christchurch that will never be the same again."
Other events around New Zealand:
Auckland
A service will be held at the Cenotaph at the Auckland Domain at 7pm.
Those who
attend the hour-long service will be encouraged to light candles and lay flowers after the ceremony.
Mayor Len Brown says it is important people take time to reflect on Christchurch's "loss, spirit, courage and resilience as New Zealand works together with the people of Canterbury in their time of need."
Free buses will run from Customs Street outside the Mercure Hotel in the CBD every 10 minutes from 5.30pm until 7pm.
Hamilton
A memorial service will be held in Hamilton's Garden Place from 12.15pm.
It will include live streaming of the Christchurch service on a big screen and an opening address by Hamilton deputy mayor Gordon Chesterman.
Hastings
The commemoration service will be screened in Hastings District libraries from 12.30pm in Flaxmere, Hastings and Havelock North.
The service will conclude at around 2.30pm and includes two minutes silence at 12.51pm, the time the earthquake struck.
Palmerston North
The national service will be broadcast at All Saints Church on 348 Church Street, Palmerston North. Doors open at noon.
Wellington
The National Memorial Service will be screened live in the TSB Bank Arena at Queens Wharf. Doors open at 12pm.
Councillor Ian McKinnon - who will be representing the council at the screening as Mayor Celia Wade-Brown is in Christchurch - says Wellingtonians have shown real empathy for the people of Christchurch.
"We also know there are now a number of Christchurch families in Wellington and this will enable them to 'stand as one' at this difficult time."
A small space will also be provided in Wellington Central Library for people to watch the broadcast.
Blenheim
A memorial service will be held at St Andrews Presbyterian Church, corner of Alfred St and Henry St (opp Seymore Sq) at 7.30pm.
Timaru
A memorial service starts at noon at St Mary's Church, 24 Church Street.
Dunedin
A memorial service will be held at Knox Church, on George St in Dunedin from 7m, and at First Church of Otago, 415 Moray Place at 12.15pm.
Invercargill
The Civic Theatre will open its doors to the public to watch the memorial service live on the big screen from noon.
