Tuesday 8 March 2011: A matter of fact
I was doing some research into earthquakes
I couldn't understand how Christchurch had such damage given the strick building codes in New Zealand.
I soon had my answer
The lateral acceleration of the quake was completely out of character for a Quake of 6.3.
The central city experienced acceleration of 1.8G (1.8 times gravity). Most of this was vertical leading to reports of people being physically thrown into the air.
To put this into perspective, the recent devastating Haiti quake reached only 0.5G. The highest measure for Christchurch was 2.2G.
Some estimates put this level of force at a once in a 1000 year event. A real test for New Zealands building standards which aim to cover a 'once in 500 year event'. Initial reports from GNS show this quake significantly exceeded even 2500-year design principles.
It is generally agreed that these levels of acceleration and force would flatten most modern cities in the world, resulting in massive loss in life.
All in all, two things are clear from the night of research.
1) Christchurch has been devastated.
2) The precautions NZ has taken have minimised a lot of the potential damage, and saved a lot of lives.