Estimating fire following earthquake risk for Wellington City, New Zealand

Abstract

Fire following earthquake (FFE) is a significant hazard in urban areas subject to high seismicity. Wellington City has many characteristics that make it susceptible to ignitions and fire spread. These include proximity to major active faults, closely spaced timber-clad buildings, vulnerable water and gas infrastructure, frequent high winds and challenging access for emergency services. We modelled the ignitions, fire spread and suppression for five earthquake sources. Uncertainty in ground motions, the number and location of ignitions, weather conditions and firefighting capacity were accounted for. The mean loss per burn zone (area burnt due to ignition and fire spread) is $46m without fire suppression, indicating the potential property damage avoided by controlling the fire spread. The mean total loss for earthquake scenarios ranges from $0.28b for the Wairau Fault through to $3.17b for a Hikurangi Subduction Zone scenario, including the influence of fire suppression. Wind speed has a strong influence on the potential losses for each simulation and is a more significant factor than the number of ignitions for evaluating losses. Areas in Wellington City of relatively high risk are identified, which may inform risk mitigation strategies. The models may be applied to other urban areas.

I Cannot Afford The Current Crisis; Let Alone Prepare For a Future One

“…Close buildings can become a massive blaze if a fire starts due to a gas leak, as experienced in the 1906 San Francisco earthquake, where a fire burned for three days and destroyed 25,000 buildings (Mondal, 2019). Post-earthquake fires can be fuelled by high winds acting as fans for the fire and carrying it between buildings, resulting in widespread damage in Wellington City (Scheele & Horspool, 2018). Large-scale fires following an earthquake could cause further harm to residents due to the increased likelihood of losing possessions following an earthquake and their houses catching fire.…”

“…Perhaps, the more 'earthquake-proof' a building is, the less likely people are to prepare as the perceived risk of an earthquake is reduced. Importantly, people need to realise that more secure buildings do not reduce the likelihood of broken water mains (Cousins, 2013b;Mondal, 2019;Potter et al, 2015), fire risk from damaged gas pipes (Mondal, 2019;Scheele & Horspool, 2018), disrupted food supplies (Mason, 2019), medical emergencies (Cousins, 2013a;Goda et al, 2018), and internal furniture damage (Cousins, 2013b;White et al, 2015), that could be mitigated and managed by preparing. This is the first time I've heard of earthquake risks Some participants explained that other elements, such as being a migrant, were a barrier to preparedness.…”

“…While the public is likely to help each other, this attitude indicates a lack of understanding about first responders and emergency and other services being disrupted. As previously discussed, Wellington City is at risk of landslides, tsunamis, liquefaction (Goda et al, 2018), fires (Scheele & Horspool, 2018), and damaged access to and from Wellington to the rest of Aotearoa New Zealand (Mason, 2019); consequently, there is likely to be delays in professional help due to Wellington City and its range of hazards and the number of people that may require assistance. Professional emergency services aim to help everyone possible; however, there is often limited supplies and more at-risk are likely to get preferential treatment than those who are younger and more capable, as suggested in a National Emergency Management Agency Review (2017) following the Christchurch earthquakes.…”

“…Current research posits that Wellington City will likely experience severe damage in a large-scale earthquake due to its geographic location, in which it is likely to become isolated from the rest of Aotearoa New Zealand and is at risk of landslides, liquefaction, tsunamis (Goda et al, 2018), fires (Scheele & Horspool, 2018), and water and food shortages (Mason, 2019;Wellington Water, n.d.a, n.d.b;Cousins, 2013b). To reduce the vulnerability that an 'young and healthy' and consequently capable of looking after themselves.…”