Christchurch Mayor Bob Parker was in Taupo at the time of the quake, and is making his way to Christchurch.
Mr Parker told One News he was "very, very concerned" about people in city, particularly with the quake coming just before Christmas.
"It sets people back," he said. "My heart just breaks. So many people have been through so much.
"This puts more pressure on people who have been through so much so far."
Mr Parker said a magnitude 6 quake had been forecast to hit at some stage.
He said the latest shaking meant the city had big step backwards again because it meant all the buildings and all the malls needed to be checked again.
"It feels like we've gone back to square one.
"It's another tough day"
- Herald Online Staff