It was like a freight train coming through the front door. No warning, no rumble, no chance of escape.

It was violent, malevolent, brutal and not remotely selective in its victims. Rising from the rock beneath Lyttelton Harbour, the Tuesday earthquake ripped through the Port Hills, shattering houses and tearing communities apart. It slammed into Christchurch. It was everybody's nightmare given seismic form.

The response was immediate and it continues to this moment. It will shape our lives for months and years to come. Within seconds of the quake ending, the rescue began. Workmates and passersby tore at the rubble of fallen and broken buildings, responding to the hundreds of cries for help.

I was on the top floor of the city council building in the central city on an outdoor deck, suddenly uncomfortably high, affording me a view I would rather not have had.

When I regained my feet I was shocked at the enormity of the destruction before me. A huge cloud of dust, the air filled with sirens and screams. The sense of panic momentarily almost overwhelming the desire to look and take stock. I could not believe what I was seeing. At times I still feel that way.

What keeps us going right now?

First, we have people to find. We will not cease our search until we have all of our extended whanau back with their families here and overseas.

We will grieve together. Then we have a city to fix. Not just fix, but reshape in a way that few generations have had the opportunity to do. Much of the CBD is gone, and sadly more will need to be cleared to make the city safe.

In this space could grow a city renewed. A city that draws on its heritage, but a city driven to contemplate a new future. And a city that honours those whom we have lost.

Christchurch can rise from the rubble, stronger, better designed and uniquely ready to face the challenges of a world vastly different from that contemplated by our founding fathers.

Together, this is something we can achieve.