The partially collapsed Christchurch Cathedral. Photo / Mark Mitchell
The Canterbury Earthquake Recovery Authority has this morning released documents relating to the Christchurch Cathedral.
The documents were uploaded onto the CERA website at 9am, and include six engineering reports by Holmes Consulting Group between November 7 and February 14, as well as communications between the authority and the Church Property Trustees.
In announcing the release yesterday, Earthquake Recovery Minister Gerry Brownlee said the information will improve the public's understanding of the damage the iconic building suffered in the February 22 and subsequent aftershocks, and the reasons behind the church's decision to demolish the cathedral.
He also called for the Anglican Church to release its reports behind the decision to deconstruct the cathedral down to 2-3 metres.
A spokeswoman for the Anglican Diocese of Christchurch, said the church would review the CERA documents and if it believed there were other "relevant, appropriate documents'', it would consider releasing them.
Meanwhile opponents of the decision to deconstruct the cathedral are this morning meeting with Anglican Bishop Victoria Matthews, with an announcement on the groups' discussions expected to be made at midday.
"Significant additional damage"
Prior to the December 23 aftershocks, the Holmes reports look at the work required to make the building safe.
A November 7 report detailed the work required to firstly make the building secure within the site boundary should there be a moderate earthquake, and secondly to allow for the contents of the cathedral to be retrieved.
A December 12 report detailed the specifics of the work required to secure the building.
However following the December 23 aftershocks, an updated report was prepared by Holmes on January 11.
It found the west wall sustained "significant additional damage" in the quakes, including the collapse of the Rose Window, and glass damage to the Hawdon Window, presumably from falling west wall debris.
The collapse of the west wall caused additional damage to slate roof of the west porch, and displaced it further to the west. The northwest corner of the porch had moved about 75mm by the west wall and is "severely cracked". However the main entrance door appeared to remain largely undamaged.
The tower also suffered further "moderate to severe diagonal cracking. The report said further partial collapse was likely in another large aftershock, and recommended additional securing works be done.
Damage to the south aisle wall was of "particular concern" as it was in a "state of severe distress".
The north and south walls were found to have sustained "additional distress" in the December 23 quakes, with existing cracks widening and new cracks forming in both walls.
The nave appeared to still be in relatively good condition, while the north and south porches suffered no additional damage.
The report recommended planned securing works be implemented as soon as possible.
Three make safe options were developed for the cathedral: Maximum retention, minimum shoring, and intermediate scheme.
On February 9, Holmes prepared a report for the work required to shore-up the building as part of the maximum retention option.
It advised the tower remnants be deconstructed to window sill level, the two south aisle wall piers be stabilised, all windows be covered with plywood and braced, the aisle roof be propped at the north and south aisle perimeter walls and the damaged transept arches be propped with timber shoring.
Holmes later completed a review into the securing work needed for the minimum shoring option, which when involve stabilising the cathedral "as a ruin".
The February 14 report said that option would enable the remnants of the building to be opened to the public, and allow for the salvage of heritage items, with minimum risk of damage.
"Experience with other buildings has demonstrated that the demolition of buildings with significant earthquake damage is difficult. It is possible that heritage items that have been identified as been critical may be significantly damaged during the make safe works."
The report details how the building will be deconstructed, and shows how much of the building will be left standing.
Among the documents released today are photos of the damage taken after the December 23 quakes, as well various emails between authorities, the church, the People's Steeple group, the Historic Places Trust and the public.
Details in many of the documents, such as names and "commercially sensitive information", have been removed from many of the documents, making it difficult to place the information in context.
Mayor wants Church to release all documents
Meanwhile Christchurch Mayor Bob Parker is echoing calls for the Anglican Church to release all its documents on the decision to demolish ChristChurch Cathedral.
Mr Parker said he did not think the release of the CERA papers today would change the church's approach.
"I think that the papers should be released, but I think what they're telling us very clearly is that their interpretation of the information they have is that the building does need to be deconstructed,'' he told Newstalk ZB.
"I think what's missing from this whole thing is some sort of vision as to what it is that they intend to do on the site.
"We've got a temporary cathedral that's going to be used for 10 years and I think for the people of Christchurch, that's just not good enough. I think we need the church to come out and clearly tell us what their plans are for the site.''
Mr Parker said the church had a vision for the cathedral site and it needed to communicate that to the rest of the community.