The Big One is coming. We can't predict when a damaging earthquake will hit Greater Victoria; it might not be in our lifetimes. We can't say for certain which buildings will topple and which will become refuges.

All we know is that some day a major earthquake will hit.

If we need a warning of how bad things might be, Christchurch offers it. The second-largest city in New Zealand was hit by a 6.3-magnitude earthquake this week, killing at least 70 people and leaving hundreds missing. It toppled the spire on the Anglican cathedral and caused widespread damage.

We all know the basic rules about surviving earthquakes -if we feel tremors, we should drop to the ground, take cover and hold on.

And we know that we should have earthquake kits in homes and workplaces -a first-aid kit, plenty of water, enough non-perishable food to last for several days, a flashlight, a battery-operated radio, batteries and other supplies.

It sounds like a checklist for a weekend camping trip. But consider what happened in Christchurch, a city of about 390,000 people.

Tourists, shoppers, office workers and residents filled the streets, trying to find safe places as buildings crumbled. People who made it to safe areas, such as stairwells, found they were trapped there by debris.

Forty-eight hours after the earthquake, there was still no accurate count of the number of people missing. The lucky ones had phones so they could let people know that they were alive. But even telephone service could not be taken for granted. Power and water were out.

Rubble from collapsed buildings filled many streets. Dust was everywhere. Some buildings were on fire. Overwhelmed emergency personnel and volunteers dug people from rubble. Several roads were left impassable because of debris, cracks, or floods of water or sludge. Tents were set up in parks to shelter the newly homeless. Residents of neighbouring communities welcomed refugees.

There are lessons for Greater Victoria. We need to pay attention so we can see what worked and what did not, and how we can become better prepared.

Not every earthquake, or every city, is the same. Much of Christchurch was built on sand and silt, so buildings were much more likely to collapse, while much of the capital region rests on rock. Still, seismic upgrading might make a difference.

But that is not the only thing we need to do -and earthquake kits are just the start.

We need to determine how we will contact families, friends and co-workers if regular communication channels are cut. We need to accept the fact that we might be living under a desk at work for a few hours, or in a stranger's house or a tent in a park for days.

We need to understand that help might not be just a phone call away. We need to be prepared, because we might need to look after ourselves, our children, our parents or our neighbours for several days.

Yes, there is a risk we will be over-prepared, gearing up for something that might not happen in our lifetimes. But it makes more sense to take precautions than to simply hope for the best.

Not convinced? Check the coverage of Christchurch and look at the photos of collapsed buildings. Then imagine the same scale of damage on Douglas Street.