Brian Rudman: Threat of earthquakes pales beside the 50 volcanoes on our doorstep

Rangitoto, sitting at our front door, a silent reminder of its violent arrival in two eruptions 600-700 years ago. Photo / Brett Phibbs

It hardly needs an official list from the council to remind Aucklanders that, like Christchurch, this city is peppered with old buildings that are likely to tumble down in a severe earthquake.

The main arterial roads through well-established suburbs such as Newmarket, Herne Bay, Mt Eden, Dominion Rd, Onehunga and Otahuhu all have clusters of 100-year-old, two-storey brick retail premises, shops downstairs, dwellings above.

In the CBD, old masonry buildings provide the "character" between the anonymous glass towers. Some have been strengthened, many not. The day after the Christchurch earthquake I emerged from a lunch bar in downtown Queens Arcade debating which side of the street would be safer to walk up if I succumbed to quake phobia.

Of course, venturing below the old harbour shoreline at Shortland St to the arcade was a bad move to start with. The old Auckland Regional Council's earthquake hazard guide warns that ground shaking would be greater in "reclaimed land such as parts of downtown Auckland". This would also be prone to liquefaction, but only if the shake was "quite a large one", the guide says, helpfully adding that in Auckland there is "a 10 per cent chance of [that] occurring in the next 50 years".

As well as buildings falling on you and silt squirting up your trouser legs at that end of town, there's the added risk of death by tsunami.

Walking back from lunch my worry was: did I zig-zag back and forth across the street to keep alongside modern structures, and risk a wayward sheet of plate glass, or just plough up either footpath regardless, praying one of my bete noire verandas wouldn't take revenge on me?

Back at work, I like to think I'd be safe in this concrete, multi-layered sandwich of a building, originally built to support huge, vibrating, printing presses. Safer, probably, than at home in my century-old brick and lime mortar pile anyway.

But let's not scare ourselves silly. Just because I've suddenly taken notice of the odd heavy truck bouncing over the slow hump outside my house in recent days, and of the odd creak of the roofing joists, it doesn't mean I'm beating a quick trail to the real estate agents.

While nothing is for certain in these shaky isles, I can live with the scientific reassurance that we don't live in an earthquake zone.

True, Christchurch wasn't on a known faultline, but it was part of what the Institute of Geological and Nuclear Sciences (GNS Science) refers to as "a well-defined [earthquake] belt stretching from Fiordland to East Cape, the Bay of Plenty", part of "the ring of fire ... rimming the Pacific Ocean".

We do get the odd noticeable shake in Auckland. In February 2007, a 4.5 jolt 30km east of Orewa had me leaping from my couch to check outside for signs of a crumpled truck. It was the strongest since 1970 when a 4.7 shake, centred on the Coromandel, rattled Auckland. GNS Science said at the time Auckland had had 35 earthquakes rating more than 3 on the Richter scale since 1830. Only one caused significant damage. Most have been to the east and south where most of Auckland's potentially active faults are.

Major public buildings such as the Town Hall, the Civic Theatre and St Patrick's Cathedral have been seismically strengthened during recent restoration work, as have renovated business premises.

Which is a sensible council requirement. But let's not get too paranoid about earthquakes in Auckland.

If we do want to fret and fuss about random acts of nature, surely it's volcanoes that should be keeping us awake.

We share this narrow isthmus with a field of 50 or so volcanic craters, the largest and most recent of them, Rangitoto, sitting at our front door, a silent reminder of its violent arrival in two eruptions 600-700 years ago.

The only good thing about our volcanoes is they rise at a gentlemanly pace of no more than 5 km/h from a lake of molten magma bubbling away 100km beneath our feet.

This gives us at least 20 hours' warning to scarper.

The brave might want to stick around to watch, in which case an existing cone would be a good choice because, Rangitoto excepted, they don't come up in the same place twice. As for me, I think it would be a good time to revisit the Aussie rellies.