Monday's aftershocks shattered many Christchurch landmarks already damaged in the February earthquake.
The collapsed Christ Church Cathedral rose window cannot be fixed, the Cathedral of the Blessed Sacrament dome is more perilous than before, the Arts Centre has suffered major damage and the timeball from the destroyed Lyttelton Timeball Station was thrown 15 metres downhill.
The Canterbury Museum collection was thrown into disorder again by the aftershocks, just days after staff had finished reordering hundreds of artefacts since the February quake.
Dean Peter Beck said most of Christ Church Cathedral's west wall had collapsed.
"We are all pretty upset at what has happened here. We have had enough, but I think we will get through this," he said.
"Clearly, we will rebuild. It will be rebuilt in some form or other, but we don't know the answers for that yet.
"After yesterday, you feel completely awful. It was not a good day. You feel exasperated and distressed."
The cathedral project manager for Holmes Consulting, Bob Blyth, said the rose window was shattered.
"I am not sure how many pieces it is in. It has fallen into the building and is in there with all the rubble," he said.
Catholic cathedral project manager John Craig, of Opus Consulting, said the dome, which was damaged in the February quake, was in a more dangerous state.
"The cathedral has sustained more significant damage," he said.
"Until we get the structural engineers to do an assessment, we won't be able to come up with definitive answers."
Two construction workers were on a platform suspended from a crane inspecting the dome when both aftershocks hit, Craig said.
"They pulled the basket away from the building pretty quickly and took it to the ground," he said.
Arts Centre engineer John Trowsdale, of Holmes Consulting, said the Great Hall and the engineering building had suffered further damage.
"All the buildings have suffered varying degrees of damage. A ... block of stone gable on the north elevation of the engineering block has collapsed," he said. "The north and south gables of the Great Hall have suffered significant damage. A couple of square metres of internal facing stone in the Great Hall has fallen in.
"We need to make the site safe again. There is a lot of work involved. There is about a month of shoring required."
Canterbury Museum director Anthony Wright said there did not appear to be major structural damage to the building.
"The really dispiriting thing is the team had just completed getting all the display galleries back to public standard on Friday. We will have to start that again now," he said.
New Zealand Historic Places Trust heritage destinations manager Paul McGahan said the timeball from the Timeball Station "rolled about 15 metres".
"The timeball didn't get far, fortunately. It is just below the big retaining wall," he said.
"A lot of the masonry that fell was contained on the platform. It is a very sad sight."
Cera orders urgent felling
More than 100 buildings in central Christchurch have been tagged for emergency demolition after Monday's earthquakes.
Canterbury Earthquake Recovery Authority (Cera) interim deconstruction manager Warwick Isaacs said engineering teams had been assessing buildings in the central city since Monday.
There had been "significant additional damage" in the red zone, with 147 buildings suffering more damage. Some of the buildings had been damaged in previous quakes, while others had not.
The Hotel Grand Chancellor had "twisted" about 75 millimetres more, while the Copthorne Hotel on Durham St had twisted a further 50mm.
Isaacs said more than 100 buildings had been marked for "emergency and urgent" demolitions because of the damage. Demolition work would start in the next two to three days, he said.
Cera chief executive Roger Sutton, who entered the red zone after the quakes, said the damage was "sobering".
"There are some streets that were badly damaged before and are really, really badly damaged now," he said.
"We're going to have to pull down some buildings quickly just so other people can get access."
- © Fairfax NZ News