To cordon or not to cordon: The inherent complexities of post-earthquake cordoning learned from Christchurch and Wellington experiences

Abstract

The use of post-earthquake cordons as a tool to support emergency managers after an event has been documented around the world. However, there is limited research that attempts to understand the inherent complexities of cordoning once applied, particularly the longer-term impacts and consequences. This research aims to fill the gap by providing a detailed understanding of cordons, their management, and the implications of cordoning in a post-earthquake environment. We use a qualitative method to understand cordons through case studies of two cities where cordons were used at different temporal and spatial scales: Christchurch (M6.3, February 2011) and Wellington (M7.8 in Kaikōura, November 2016), New Zealand. Data was collected through 21 key informant interviews obtained through purposive and snowball sampling of participants who were directly or indirectly involved in a decision-making role and/or had influence in relation to the cordoning process. The participants were from varying backgrounds and roles i.e. emergency managers, council members, business representatives, insurance representatives, police, and communication managers. We find that cordons are used primarily as a tool to control access for the purpose of life safety and security, but cordons can also be adapted to support recovery. Broadly, our analysis suggests two key aspects, ‘decision-making’ and ‘operations and management’, which overlap and interact as part of a complex system. The underlying complexity arises in large part due to the multitude of sectors affected by cordons: economics, law, politics, governance, evacuation, civil liberties, available resources etc. The complexity further increases as the duration of cordoning is extended.

Understanding the wider social and economic context of post-earthquake cordons: A comparative case study between Christchurch, Aotearoa (New Zealand) and L’Aquila, Italy

“…A cordon is a visible barrier used by an authorized institution to temporarily manage access to and from a given site during critical situations. In relation to earthquakes, the criticality of the situation is indicated by the risks from damaged buildings and potential falling debris due to aftershocks that follow major seismic events (Shrestha et al, 2021). Cordons impose a strict spatial demarcation that delineates the degree of safety and security within it.…”

Prioritising earthquake retrofitting in Wellington, New Zealand

“…For the spatial location criterion, the study measured the building's distance from emergency transport routes (as defined by Wellington City Council), the number of crossroads within a 50-metre radius of the building, and the height of a building as a proxy for how its failure will expand the required cordon-see Shrestha et al (2019) for information on the detrimental impact of a long-term cordon after a seismic occurrence. Data on other lifeline networks (such as electricity and water) were not used, as these are all below ground, and nothing was known about their vulnerability to a building failure.…”

“…This risk is not only to life safety, but also to the ability of the city to continue functioning after an earthquake. A long‐term closure of Wellington's CBD, similar to what occurred in Christchurch after the earthquake of 2011, will have a far‐reaching detrimental impact on the local and national economy (Shrestha et al, 2019). In light of these concerns, it is in the interest of the city's government to facilitate a deliberate programme of retrofits and demolitions that will increase Wellington's resilience to seismic events in the future.…”

High-resolution post-earthquake recovery simulation: Impact of safety cordons

“…When considering the performance of a dense urban downtown area, it is important to recognize the potential for widespread access restrictions due to post-earthquake safety cordons (hereafter, cordons). Cordons restrict access into potentially dangerous zones, preventing casualties in the event of an aftershock by inhibiting the zone’s pre-earthquake community functions (Shrestha et al, 2021). The February 2011 Canterbury earthquake in Christchurch, New Zealand demonstrated the potential scale and political/legal challenges of this issue, with cordons restricting access to the Central Business District (CBD) for many months after the earthquake (Chang et al, 2014; Marquis et al, 2017; Underwood et al, 2020).…”