The mayor of Christchurch has refused to commit to memory the name of the man who carried out mosque shootings in the city, in a decision that she says is echoed by her community and is a crucial part of recovering from the atrocity.

But Lianne Dalziel said the way the city’s Muslims had chosen to forgive him was also essential, and had made the New Zealand city stronger and safer.

Speaking to the Guardian on a visit to the UK before a European conference on how cities can recover from disasters, she said all cities could learn from the resilience Christchurch had shown. But she is still raw about happened when a 28-year-old white supremacist murdered 51 people at two mosques with military-style weapons and livestreamed the attack.

“I hope he rots in hell and rots in jail,” she said.

Lianne Dalziel and Sadiq Khan at City Hall in London. Photograph: Lianne Dalziel

After the attack New Zealand’s prime minister, Jacinda Ardern, vowed never to mention the attacker’s name in public. The media in New Zealand has largely followed her example by mentioning his name only when it is unavoidable.

But even before Ardern’s announcement, Dalziel said the city had collectively decided to render the attacker nameless. “It was just instinctive. Why would I want to give him what he wants? He craves attention.” And she claimed to have gone further by forgetting his name. “I didn’t want to hear his name even when they released it. You know, how you commit names to memory. I’ve no idea what his name is.”

The conscious effort in Christchurch to sideline the attacker chimes with wider arguments about how such atrocities should be described in the press and on social media. As the frequency of such attacks has increased in recent years, criminologists and affected communities have argued strongly that an excessive focus on the personal details of the killer simply serves to make their goal of notoriety seem more achievable – the so-called contagion effect.

Jacinda Ardern leaving Friday prayers at Hagley Park in Christchurch after the attack. Photograph: Vincent Thian/AP

“A lot of these shooters want to be treated like celebrities,” Adam Lankford, a criminologist at the University of Alabama in the US, told AP earlier this year. “They want to be famous. So the key is to not give them that treatment.”

During the remembrance service for the victims Dalziel spoke of her determination for Christchurch not to be defined by the attacks. More than three months later she claimed it was the defiant response to the attacks the city would be remembered for.

She added: “The response was so overwhelming that he hasn’t achieved what he intended. He has drawn people people together. It’s safer in the sense that we’re much more aware of our communities around us. There is a much clearer understanding of where division and othering leads.”

Flowers left to remember victims in Christchurch. Photograph: Sanka Vidanagama/AFP/Getty Images

She praised the leadership shown by Ardern and the “incredible outpouring of love” from people in the city. “Every single member of the Muslim community that I’ve spoken to have all mentioned how much the support meant to them personally,” she said.

But it is the response from the members of that community that seems to have impressed her most. She singled out Gamal Fouda, the imam of the Al Noor mosque, who at a call to prayer a week after the shootings said: “We are heartbroken but will not be broken.”

Dalziel said the speech was “outstanding” and played a key part in uniting Christchurch in the aftermath. But she admitted she did not share his capacity to forgive.

“All of the expressions that came out from the Muslim communities were of peace, love and forgiveness – an infinite capacity for forgiveness that I will never, ever, ever, ever feel.”

Dalziel is in the UK for talks with the London mayor, Sadiq Khan, and to launch the British arm of the Christchurch Foundation, a charity that has raised more than $NZ10m (£5.3m) since the attacks. She is also due to speak in Rotterdam on Tuesday at a summit on urban resilience. She signed up to become part of the resilient cities network in her first act as mayor in 2013 as her city struggled to recover from the 2011 earthquake that killed 185 people and caused widespread damage.

Her commitment to the idea of urban resilience has been reinforced by what has happened since the attacks but has also been adapted to focus more on strengthening communities in the face of extremism.

She said: “You cannot be a resilient person if you yourself are feeling judged or under attack just because of the colour of your skin or the religion you practise. Resilience is very much based on connected communities that are genuinely inclusive and embracing of diversity.”

She added: “The very foundation of resilience is communities understanding that they have an incredible capacity within themselves to respond to any particular events that come their way. And if they realise that capacity before a disaster they are in much better position to respond better and faster.”

Asked if the UK could learn to be more resilient as it prepares for a potential no-deal Brexit, Dalziel puts her head in her hands. “It looks very difficult,” she said. “You just have to work with what you have got, but at a city level it is achievable.”

Dalziel has backed the reform of New Zealand’s gun laws but wants the government to go further by banning the type of ammunition that was used in the shootings. “He used soft-nosed bullets that caused incredible damage,” she said, pointing out that many of the injured spent hours in surgery in part because of the ammunition used. “They are designed to do great damage and they did.”

She has also urged Facebook to introduce safeguards to ensure that atrocities are not livestreamed. “It took Facebook longer to take it down than it took the police to arrest the guy. They should be ashamed of themselves.”