The Alpine fault and the active faults of New Zealand.

The South island's faults.

The Australian plate and the pacific plate in the South Island have formed the most dense clusters. The faults in the southern part of the Island, branch off and are the much larger. The Alpine fault which is the longest fault in New Zealand is also the longest straight fault in the world, spanning 500km in a straight line, and the full length of the fault line is about 600km. The fault patterns follow the edge of the tectonic plates, as the majority of the fault lines in the South Island are located up in Christchurch and beyond, and the rest are scattered across the rest of the South Island. As in the North Island, almost every single fault line is brushed across the eastern side of the Island, and the faults are very scattered, much more than in the South Island. This is due to the fact that New Zealand is right in between two tectonic plates, which are constantly pushing, sliding and going under each other, which produces thousands of tiny earthquakes a day and many many faults across New Zealand.

the different ways faults form in New Zealand.

The Faults of New Zealand are formed via the Pacific plate and the Australian plate moving in a subduction, sliding and spreading motion, which in the South Island caused the formation of the Alpine fault. The other faults are scattered across the Canterbury Plains down to Southland, while the faults in the upper part of Canterbury and beyond are more condensed due to the Alpine fault branching off into many different faults. This is caused by the Australian plate and pacific plate pushing together in a transform motion which has caused the Alpine fault and the other faults that branch off it.

Impacts of the rupture of faults

In 2011, February 22th, 12:51pm, a magnitude 6.3 earthquake hit Christchurch, the earthquake itself was 6.7km away from Christchurch's central business district and it's depth was 5km. The actual earthquake wouldn't have been that destructive if the shockwaves of the earthquake hadn't reflected off a hill of basalt and redirected the waves towards the business district, which at the time, the buildings were at least fourteen stories high and were not designed to withstand an earthquake. This resulted in the loss of 185 deaths, approximately 1500-2000 people were injured, with 164 people being seriously injured. The damage from the earthquake resulting in damages excessing 44 billion dollars.

The reason why the 2011 earthquake was much more destructive and deadly than the 2010, was due to it being a magnitude of 7.1. There are several reasons why the 2011 earthquake was worse than the one a year before. Firstly, it was much closer to Christchurch city centre as it was only 6.7km away, while the 2010 earthquake was 40km away. Secondly, the depth of the earthquake in which occurred was also significant, being that the 2011 earthquake happened at 5km deep as opposed to the 2010 earthquake, being 10km. Another contributing factor was the time of day, in the 2010 earthquake, it happened at 4am as opposed to the 2011 when it occurred during the middle of the day, 12noon. This meant that there were a lot more more people out and about or at work.

Another major contributing factor was the basalt hill and how it redirected the seismic waves back towards the city which are believed be have amplified due to the soft unstable ground, which resulted in extensive damage to infrastructure and the loss of life.

In response to the 2011 earthquake, the Christchurch council decided on making sure no buildings from 2011 onwards be more than 2 stories tall in the city center. They introduced new and improved building consents in an attempt to minimize damage in the future should earthquakes occur and hopefully save lives.