Fire and Emergency is dropping its investigation into what caused the Port Hills fire due to a lack of evidence.
Firefighters try to save a house from fire on Port Hills in Christchurch. Photo: Supplied
Two fires on Christchurch's Port Hills tore through about 1600 hectares of forest almost a year ago, gutting nine homes and forcing thousands of residents to evacuate.
Helicopter pilot Steve Askin also died fighting the fire, which took 66 days to completely extinguish.
Fire and emergency chief executive Rhys Jones said he believed both fires were deliberately lit, but their investigation was now closed due to a lack of evidence.
"The lack of physical evidence or being able to interview anyone responsible has made it very difficult to determine the cause and origin conclusively," he said.
"However, Fire and Emergency New Zealand believes both were deliberately lit and the matter remains in the hands of the police."
Fire and Emergency has also released its first progress report on recommendations made by a review of how the fire service responded to the disaster.
The review, which was released in November 2017, found there was a communication breakdown by the fire service, and some houses could have been saved if a different approach was taken.
Mr Jones said the fire service had made progress addressing the problems.
"Our urban and rural firefighters are training together and with partner organisations on a regular basis," he said.
"We are trailing community based approaches to fire risk assessment and prevention, and improving how we communicate with the public during incidents."
He said another progress report would be completed in July.
The Port Hills fire - how it happened
13 February 2017 - Two scrub fires ignite overnight and start spreading on Christchurch's Port Hills. One was centred on Early Valley Road near Tai Tapu and the other was close to the Dyers Pass Road by the Sign of the Kiwi. At this time, the fire service said "about 20 hectares of scrub were burning and the fires were moving fast".
14 February - Fires continued to burn, one home was lost. Eleven helicopters with monsoon buckets were en route to fight the blaze. That afternoon helicopter pilot and decorated SAS soldier, Steve Askin, died after his helicopter crashed near Sugarloaf communications tower. The fire continued to grow.
14 February - The fire service said the fire was "contained".
15 February - Both fires flared up overnight. A dozen helicopters and almost 100 crew fought the fires. Minister of Civil Defence Gerry Brownlee described footage he had seen of the fire as "terrifying" but questioned whether emergency services were adequately prepared for it. Mr Brownlee said a state of emergency should have been declared. Christchurch and Selwyn mayors declared a joint State of Emergency. Thousands of residents on the Port Hills were evacuated with police cordons set up. Civil defence said 40 homes were destroyed. Evacuation centres set up.
16 February - The two fires merged into one blaze in excess of 1850ha overnight. The fire started moving towards the city after a big wind shift. Civil Defence corrected yesterday's report saying 40 homes were destroyed, saying "two to three" houses were burnt. By the end of the day they said 11 houses were destroyed. The then-prime minister, Bill English, arrived in Christchurch for a briefing. Christchurch mayor Lianne Dalziel and Selwyn mayor Sam Broughton responded to Gerry Brownlee's criticism, defending their approach. The fire had now been burning for almost four days, and was not in control.
17 February - Selwyn District principal rural fire officer, Douglas Marshall said reinforcing containment lines would be the focus for 300 firefighters battling the blaze. There was confusion at police cordons, where residents complained that some were let through but others were not. Fire investigators arrived on site. The New Zealand Defence Force brought in firefighting equipment from Australia. Port Hills homeowners said they were frustrated by "poor communications". Two cordons were lifted.
18 February - More cordons were lifted, but about 100 homes were still off limits. About 400 people turned up to a meeting in Sydenham in the morning morning with Christchurch mayor Lianne Dalziel and emergency service officials, and accused them of poor communication and demanded to know why they had not been able to access their properties when it seemed the danger was over. Ms Dalziel apologised.
19 February - The fire service said the blaze was "under control" but would remain a threat for another week. Residents told RNZ they were still frustrated by a lack of communication from Civil Defence.
20 February - About 600 people gathered for helicopter pilot Steve Askin's funeral, at Christchurch's Air Force museum.
21 February - Two key cordons were lifted on Kennedy Bush Road and Hoon Hay Valley Road, with queues of residents eager to return home. A state of emergency was extended for another week.
22 February - Residents from Worsley Road, one of the worse hit areas, were allowed to return home.
24 February - The fire service said fire fighters would continue to work on the Port Hills for the next four weeks.
6 March - Ecologists warn the Port Hills could take "decades" too recover.
13 April - The Insurance Council said insurers had paid out almost $18 million for damage from the Port Hills fires.
20 April - The fire was finally extinguished after more than two months. It had burnt through about 2000ha of forestry, damaged Christchurch's newly reopened Adventure Park, and destroyed nine homes (this was the final number confirmed by Fire and Emergency).
11 May - A Transport Accident Investigation Commission report found the helicopter crash that killed Steve Askin was caused by monsoon bucket cables.
17 July - Police announced it was launching a criminal investigation into the fire that started on Marley's Hill, which was described as "suspicious". The fire service said investigations into the Early Valley Road fire were still ongoing.
18 October - Insurer IAG announced it was taking action against the Christchurch Adventure Park for allegedly spreading the fire via its chairlift, and lines company Orion Group, for an alleged failure in electrical equipment. Orion Group denied this.
3 November - The fire service said it was treating both fires as suspicious. An independent review, released by the newly formed Fire and Emergency (which combined the rural and urban fire services under one organisation), acknowledged that some houses destroyed in the fires may have been saved if a different approach had been taken. It identified communication breakdowns with affected Port Hills residents and a lack of cohesion between the Urban and Rural Fire Authority.
5 November - Christchurch Adventure Park reopened.
30 January 2018 - Fire and Emergency announced it had closed its investigation due to a lack of evidence.