What people refer to as the Christchurch earthquake was actually an aftershock of the first quake in September. The destructiveness of the February 2011 aftershock displaced the earlier incident as “the quake” and deservedly so.
Christchurch earthquake 6.3 magnitude on the Richter Scale. (Why Can’t Kiwi’s Fly?, p. 56):
A more accurate measure of how strong an earthquake feels or how much damage it causes is the Modified Mercalli Scale. It gauges the effects of an earthquake on the Earth’s surface, humans, buildings, and trees. It has a scale of I –XII (1-12); on this scale the Christchurch earthquake is rated IX (Violent: general panic, damage considerable in specially designed structures, well-designed frame structures partially collapse. Buildings shifted off foundations.) Some argue the Christchurch earthquake should have been rated as high as X (Intense: some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundation. Rails bent. Large landslides.)
Another measure of the strength of an earthquake is peak ground acceleration or PGA. This does not calculate the total energy (magnitude or size) of an earthquake, but rather how hard the earth shakes. On that scale the Christchurch earthquake recorded one of the highest PGAs ever: at Heathcote Primary School it was an incredible 2.2 g, or 2.2 times the acceleration of gravity. And to compound the destruction, the greater force was upwards, with people lifted off their feet. Only the recent Japanese earthquake in Tohuku, on 11 March 2011, recorded a higher PGA—2.7g.
As geologist Hamish Campbell said: “No wonder so many stone churches, including Christchurch Cathedral, were destroyed. Such structures were simply not designed to be thrown up into the air and left to go into free fall, even though the fall is all over in a matter of milliseconds to seconds.
I first visited Christchurch in October 2010. I experienced a small roller during my stay, but I’m from California so I wasn’t unnerved. I’ve never experienced what Christchurchians did for a period of several years: a seemingly never ending series of aftershocks of varying strengths. I feel like I followed it with the Ole JackMeter. My friend David introduced me via Facebook to Ole and Karen and I visited them and got the deluxe tour of Christchurch and Banks Peninsula in October 2010. They were away from Christchurch on the fateful day in February, but they endured many more sleepless nights. It was not uncommon to be woken up by the sound of a train–held in suspense as to the size of the coming trembler. Ole posted on Facebook when there was another significant quake by saying something like it was another “Jack night” meaning he was going to need Jack Daniel’s whiskey to get to sleep. Whenever I read this from my home in California I’d say a little prayer and think of the beautiful city in Canterbury.
Ole and Karen gave me another tour in 2013. Streets and sewer lines were dug up for repairs almost everywhere we drove. Places I had admired in 2010 were in ruins or closed. Upheaval was ongoing including occasional aftershocks. There were also signs of vitality. The Restore Mall had recently opened with shops in shipping containers.
UK Sarah made time on our road trip to meet Ole for breakfast (Karen was on a business trip) and he gave us another deluxe tour. The roads are in much better shape. There are more and more signs of life returning to normal. The Children’s Bookstore I love is closing/for sale; however, it is hard to say if it is earthquake or book industry related. Now the Sumner suburbs are completely cleared and going back to nature. The fallen rock along the Redcliffs is almost completely removed and many people have already rebuilt to a new standard.
I predict that Christchurch will go from tragedy to triumph. It takes time. And they’ve only just stopped shaking.
This documentary gives a moving account of the “big one”.
Postscript: Their Monday morning they experienced more earthquakes (7.8 Richter, 5+ aftershock(s)). The epicenter was further north near Kaikoura. I am sad to see the photos of the destruction of this beautiful seaside town. My prayers are with them. We can also donate to the NZ Red Cross.