Post-earthquake Demolition in Christchurch, New Zealand: A Case-Study Towards Incorporating Environmental Impacts in Demolition Decisions

Abstract

The 2010/2011 Canterbury Earthquake Sequence resulted in severe loss and disruption in Christchurch, New Zealand due to liquefaction and damage from strong shaking. Following the earthquake, over 60% of concrete buildings with 3 + stories in the Christchurch CBD were demolished, resulting in a widespread displacement of people and business, an excess of $NZD 40 billion in losses, and significant environmental impacts from the demolition. Following the event, it was revealed that environmental impacts were not a direct consideration in demolition decision making. This paper provides a quantitative evaluation of the environmental impacts of the demolitions in Christchurch to highlight the importance of including environmental considerations when deciding between repair or demolition of a damaged building. First, the quantitative and qualitative factors that led to the demolitions following the Canterbury Earthquake Sequence are discussed to provide context for the argument that environmental impacts should be included in such considerations. Next, the environmental impacts of building demolitions in Christchurch are presented in terms of the embodied CO2 and energy in the building materials; the demolition process and waste disposal are not considered in this initial evaluation. Finally, a brief discussion on incorporating environmental impacts into the demolition decision making paradigm is presented. Moreover, consideration of environmental impacts of demolitions supports the need to move toward low-damage design in the future evolution of building codes.

Earthquake Resilient near Zero Energy Buildings: Attributes and Perspectives

“…Moreover, the collapsed buildings should be replaced with new ones. As an example, approximately 70% of the district of Christchurch, after the 2011 earthquake, was demolished (namely, over 60% of the reinforced concrete building with three stories and more, around 1000 commercial properties, and 10.000-15.000 residential properties) [20,21]. The recent Kahramanmaras earthquake in Turkey in 2023, which affected nearly 16 million people, resulted in approximately 280.000 buildings collapsing or being severely damaged; hence, it was the second most severe case of post-earthquake demolition [22].…”

Enhancing Seismic and Resilient Performance of Resilient Walls with Concealed Bracings: Experimental and Numerical Investigation

“…During a series of earthquakes in New Zealand in 2010-2011, 60% of buildings with more than three stories in the Christchurch CBD were demolished due to repair costs being much higher than reconstruction costs. The demolition also had a significant impact on the environment and economic, with the loss exceeding NZ $40 billion (Gonzalez et al 2021). Furthermore, the earthquake that struck Turkey in 2023 resulted in severe damage to over 300,000 buildings, which were damaged beyond repair and slated for demolition.…”

Influence of Prior Shaking on Seismic Drift Demands

“…Current building code provisions require a designer to consider the drift response of a structure to a single high-intensity earthquake event. These design practices can produce structures which must be demolished and reconstructed after each high-intensity motion as was the case for 60% of buildings in the Christchurch Central Business District following the 2011 Christchurch, New Zealand earthquake (Gonzalez, Stephens, Toma, Elwood, & Dowdell, 2021) 1 . To reduce monetary and environmental costs associated with such demolition and reconstruction, structures need to be proportioned to resist more than one strong ground motion.…”