The shakes at the top of the south are a timely wake-up call for Wellington and the rest of New Zealand.
OPINION: Christchurch people know earthquakes all too well; we have been shaken by more than 13,000 of them since September 4, 2010. Wellington, however, despite sitting right on a fault line, has escaped any major quakes - until now.
The capital has been shaken out of its complacency, and that can only be a good thing.
When we visited Wellington, most people seemed oblivious of the risks of living in an earthquake-prone city.
Some seemed bemused that we should feel nervous in parts of the central city. Christchurch Mayor Bob Parker said he felt the same way, remarks that some people regarded as odd.
What lessons could Christchurch people share that might help other parts of the country?
Understanding the risk is vital. Those who experienced both the Christchurch quakes and the Wellington/Marlborough quakes say the Christchurch ones felt stronger. Any big earthquake feels scary.
However, the Richter scale alone is not the best indication of likely damage. Think magnitude, location, depth and duration.
The July 21, 2013 Seddon quake was a magnitude 6.5, 20km east of Seddon, at a depth of 17km, and lasted about 20 seconds.
The February 22, 2011 Christchurch quake was a magnitude 6.3, 10km south-east of the centre of Christchurch, at a depth of 5km, and it also lasted about 20 seconds.
According to GNS, the maximum ground shaking recorded in Christchurch on February 22 was 10 times more powerful than the 6.5 Seddon earthquake.
Another, lesser-used scale is the Modified Mercalli Intensity (MMI) scale.
The MMI intensity in the 6.5 quake reached VII (very strong), as opposed to VIII to IX (destructive to violent) in Christchurch on February 22, about the same as parts of Japan in the devastating Tohuku earthquake of March 11, 2011, a massive magnitude 9.0 offshore earthquake.
What is clear is that if the Seddon earthquake had been closer to the capital, at a shallower depth, damage would have been significant.
Even a smaller magnitude quake could prove deadly. Christchurch failed to appreciate this risk following the initial, September 4, 2010, magnitude 7.1 Darfield earthquake.
Damage depends on many factors, including the nature of the land.
In Wellington, part of the central city is built on reclaimed land. Much of Lower Hutt is built on soft soil, so liquefaction could occur. Hillsides may give way.
Infrastructure will be knocked out. Power lines will come down. Roads will become impassable. Train networks will stop. The airport will close. Telephones, including cellphone networks, will become paralysed. Water may be shut off. You won't be able to have a shower or flush the toilet.
Tall high-rises, though they feel scary, should be relatively safe, but people may be trapped in lifts. The safest place should be Te Papa, which has base isolators.
What would happen to those old masonry buildings and facades in Wellington in a big quake? In Christchurch, they collapsed instantly, in seconds. People had no time to escape.
How you react may save your life. Drop, cover, hold is what we are taught. It isn't what I did on February 22, 2011.
I swayed across the first floor of the Christchurch Central Library and braced myself against a massive concrete pillar underneath an equally massive concrete beam. I figured if they collapsed, there was nothing I could do.
At home I went for the door frame. My nephew, who is a student at Victoria University, shares an inner-city Wellington flat. Flatmates have a massive table they could shelter under.
There are many things you can do right now to cope in the aftermath of a quake: Get an emergency kit, with torch and batteries, water bottles, tinned and dried food, and a transistor radio. Make sure you have a corded phone. Move fragile and heavy objects to lower shelves. Secure large televisions and hi-fi speakers. Do a safety audit of your house.
Major prevention measures are up to the authorities.
After the first big quake, the Christchurch City Council concentrated on "business as usual" and carried on with useless projects like extending the tracks for the inner-city tourist tram.
It should have insisted on the enforcement of tough, rigorous safety standards to properly strengthen at risk-buildings in the event of another major shake.
Wellington, and other parts of New Zealand, now have that responsibility. Some towns have moaned that making buildings more earthquake resistant, and meeting an arbitrary percentage of the new building code, is just a burden or another compliance cost.
What nonsense. What is a life worth?
And while building better will cost more, that pales into insignificance against the cost of demolition and rebuilding from scratch.
You cannot rely only on insurance companies and EQC.
- The Press