Hibbs lost her mother Heather Marilyn Meadows in the CTV collapse and McGregor her grandfather, Barry Craig, in the PGC building.
The Governor-General, Dame Patsy Reddy, will also perform a reading and there will be a message from former mayor Sir Bob Parker, who has suffered a stroke.
Prime Minister Jacinda Ardern will be in attendance and address the crowd.
New Zealand flags on all government and public buildings will be flying at half-mast on the day at the request of Ardern.
The service will be held at the Canterbury Earthquake National Memorial on the corner of Montreal St and Cambridge Terrace.
The full run-down of the service:
12.30pm
• Service commences. Karakia and mihi whakatau by Ngāi Tūāhuriri Upoko, Dr Te Maire Tau.
• MC Lieutenant Mark Hadlow, RNZNR, ONZM.
• Words of welcome by Mayor Lianne Dalziel and Quake Families Trust committee member Professor Maan Alkaisi.
• Reading of the names. The names of the 185 people who lost their lives will be read by first responders and members of the community.
12.51pm
• Minute of silence observed
• I live on read by Julie Hibbs and Vanessa McGregor.
• Hokihoki Tonu Mai performed by the New Zealand Army Band.
• Reading by Dame Patsy Reddy GNZM, QSO Governor-General of New Zealand.
• Message from former Mayor of Christchurch, Sir Bob Parker.
• Address from Prime Minister Jacinda Ardern.
• Closing karakia and blessing by Ngāi Tūāhuriri Upoko, Dr Te Maire Tau.