ES AT1 2017 Case Study: Christchurch Earthquake
Part A: Analysis of Event
Analysis of the tectonic movement or process involved
The Christchurch earthquake in 2011 was a result of a transform boundary. Transform boundaries are when two separate plates slide past each other in their movement. During this process of movement, lithosphere is neither created nor destroyed. Many of these transform boundaries are found on the seafloor. This slide of plates can often lead to major earthquakes. In the central south island of New Zealand, consisting of Christchurch, much of the plate movement and collision is taken up by the movement across the Alpine Fault. The movement across this fault is mainly transform boundaries as the plates shift together …show more content…
The earthquake struck at a shallow depth of 5kms and was measured at 6.1 on the Richter scale, this disaster affected the majority of the southern island and the base of the northern island of New Zealand, showing the dramatic proportion of the damage that occurred. The city of Christchurch however was the hardest hit and the surrounding area which covered 1,426 square kilometres. Approximately 100,000 buildings were damaged from the earthquake and roughly 10,000 buildings had to be knocked down. The cause of the serious damage in city was the process of liquefaction. Over thousands of years, sediment was deposited in the Christchurch area, the top layer of this sediment hardens and dries, making it seem like a good spot to build on. Underneath this hard layer however, was underlying layers that consisted of silt and sand mixed in with water. During the 2010 Canterbury earthquake these layers of silt and sand were shaken and stirred up, liquefaction occurred in some areas but was mild in comparison to the Christchurch earthquake. As a result of the previous earthquake, the liquefaction process occurred at a more significant extent, the silt and sand had already been disturbed, so the second time around when the ground shook, sodden silt rose from cracks in the ground and flooded a significant section of the city. Streets and houses were flooded with this sludge-like mixture and the foundations of many houses and buildings were destroyed. This destruction was worst in the eastern areas of Christchurch, this is because there was previously a swamp there, the liquefaction was at it’s height in the eastern area of Christchurch, and it is likely that re-building will never take place in this area
Part A: Analysis of Event
Analysis of the tectonic movement or process involved
The Christchurch earthquake in 2011 was a result of a transform boundary. Transform boundaries are when two separate plates slide past each other in their movement. During this process of movement, lithosphere is neither created nor destroyed. Many of these transform boundaries are found on the seafloor. This slide of plates can often lead to major earthquakes. In the central south island of New Zealand, consisting of Christchurch, much of the plate movement and collision is taken up by the movement across the Alpine Fault. The movement across this fault is mainly transform boundaries as the plates shift together …show more content…
The earthquake struck at a shallow depth of 5kms and was measured at 6.1 on the Richter scale, this disaster affected the majority of the southern island and the base of the northern island of New Zealand, showing the dramatic proportion of the damage that occurred. The city of Christchurch however was the hardest hit and the surrounding area which covered 1,426 square kilometres. Approximately 100,000 buildings were damaged from the earthquake and roughly 10,000 buildings had to be knocked down. The cause of the serious damage in city was the process of liquefaction. Over thousands of years, sediment was deposited in the Christchurch area, the top layer of this sediment hardens and dries, making it seem like a good spot to build on. Underneath this hard layer however, was underlying layers that consisted of silt and sand mixed in with water. During the 2010 Canterbury earthquake these layers of silt and sand were shaken and stirred up, liquefaction occurred in some areas but was mild in comparison to the Christchurch earthquake. As a result of the previous earthquake, the liquefaction process occurred at a more significant extent, the silt and sand had already been disturbed, so the second time around when the ground shook, sodden silt rose from cracks in the ground and flooded a significant section of the city. Streets and houses were flooded with this sludge-like mixture and the foundations of many houses and buildings were destroyed. This destruction was worst in the eastern areas of Christchurch, this is because there was previously a swamp there, the liquefaction was at it’s height in the eastern area of Christchurch, and it is likely that re-building will never take place in this area