INJURY AND HARM Marked decline of sudden mass fatality events in New Zealand 1900 to 2015: the basic epidemiology Nick Wilson,1 Adrienne Morales, 1 Nicola Guy, 1 George Thomson1 ass casualty events are important Abstract internationally, with one report Midentifying 749,000 earthquake Objective: To describe the basic epidemiology of sudden mass fatality events for the 1900 to deaths in the past 20 years, more than 2015 period in New Zealand (NZ). 160,000 heatwave deaths and more than Methods: Official lists and internet searches were used to identify the events. Events were 1 130,000 deaths from one storm. The number categorised, rates calculated and time trends analysed. of weather- and climate-related disasters has Results: A total of 56 sudden mass fatality events with 10 or more fatalities between 1900 and more than doubled over the past 40 years, 2015 in NZ were identified. There were 1,896 deaths in total, with the worst event being the accounting for 6,392 events in the 20-years Hawke’s Bay earthquake (258 deaths). Events were classified as transportation-related (64%), 1996–2015, up from 3,017 in 1976–1995.1 natural causes (11%), industrial (9%), war (9%) and infrastructure (5%). There were marked Even though developing countries declines in the rate of events per person-years of exposure and the associated mortality rate experience relatively high mortality burdens (both p<0.0001). Knowledge gaps were identified around: i) the basic epidemiology, e.g. non- from such disasters, no country is immune. fatal injuries and numbers of survivors; ii) the role of subsequent official inquiries in guiding In New Zealand, for example, the Canterbury preventive measures; and iii) the likely cost-effectiveness of measures to prevent harm from earthquake caused 185 deaths, and 6,659 such events. people were injured in the first 24 hours.2 The Conclusions: The occurrence and health burden of sudden mass fatality events have markedly NZ Treasury has estimated the cost of this declined in NZ over time. earthquake to be around NZ$40 billion for capital costs alone.3 In the aftermath of such Implications for public health: There remains large scope for addressing the knowledge gaps events, large resources are also typically spent in the basic epidemiology and societal responses to these events to guide primary prevention on official inquiries, e.g. the inquiry into the and appropriate disaster response. Canterbury earthquake produced seven very Key words: mass fatality events, disasters, official inquiries detailed volumes.4 These inquiries may also lead to new practices and new laws – which Methods spread out over weeks, months or years (e.g. also can involve large levels of resource use, the 1918–1919 influenza pandemic and the such as with new building regulations for Event definition 1957–1959 influenza pandemic).7 earthquake resistance. We defined a sudden mass fatality event as Despite such impacts, we could not identify one that involved 10 or more fatalities, as per Identifying events any basic descriptive epidemiology of such one component of a previously published Most events were primarily sourced from mass fatality events for NZ. Indeed, official framework for “mass casualty incidents”.6 The an official list of disasters8 but with various lists of ‘disasters’ in NZ were not systematically ‘sudden’ component of the event required additions and subtractions based on collated and appear incomplete in various that most of the deaths occurred within a 24- additional searches. Most additions arose ways. An Australasian study provided hour period. The location – NZ’s boundaries from a detailed text on NZ shipwrecks,9 but descriptive epidemiology that included NZ in 2016 – included the country’s Exclusive others came from searches of online lists, e.g. events, but that list was also incomplete Economic Zone (EEZ; 200 nautical miles out to for air transport crashes and mass homicide and there were no NZ-specific analysis sea) and its territorial claim on Antarctica (the events. Subtractions relative to the official and trends.5 To facilitate further analysis of Ross Dependency). The time period used was list arose from definitional issues e.g., the this topic, we aimed to describe the basic 1900 to 2015. We excluded epidemics and 1988 Whanganui air crash in an official list8 epidemiology of sudden mass fatality events pandemics, given that these did not meet our appears to have involved nine rather than (10 or more deaths) in NZ for 1900 to 2015. criteria for being sudden as they are typically the 10 fatalities assumed. Events outside NZ’s 1. Department of Public Health, University of Otago, New Zealand Correspondence to: Professor Nick Wilson, Department of Public Health, University of Otago, PO Box 7343, Wellington South, Wellington 6021, New Zealand; e-mail: [email protected] Submitted: June 2016; Revision requested: October 2016; Accepted: November 2016 The authors have stated they have no conflict of interest. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Aust NZ J Public Health. 2017; 41:275-9; doi: 10.1111/1753-6405.12652 2017 VOL. 41 NO. 3 Australian and New Zealand Journal of Public Health 275 © 2017 The Authors Wilson et al. Article EEZ were not included, given our definition categories. Some of the early inquiries into events, a flood and a major storm. Following of an event (e.g. various ship sinkings, such as ship sinkings were held in Australia and we this were industrial causes (9%), with all four the Turakina and Rangitane in 1940, and air included these. related to coal mining; those related to war crashes of two NZ Air Force bombers on route (9%); and those related to infrastructure (5%), from Fiji to NZ in 1944). Denominator data and rates i.e. two fires and a platform collapse. However, After this initial search work, a comparison Population denominator data was sourced multiple causal pathways were often involved was made with the Australasian study by from Statistics NZ for mean population and such nuances are not captured in Table 1. Bradt et al.5 that covered the period 1900 estimates by year.13 Where these data were For example, some of the transport-related to 2012 (and included 38 events with missing for specific years (in those prior to events such as ship sinkings were also 10+ fatalities). This comparison resulted 1926), we interpolated from the five-yearly sometimes related to storms and so could be in no changes in the number of events Census values (assuming linear population partly related to natural events. Also, some but stimulated further research by us to growth). Rates for events and deaths were transport-related shipping events could also identify additional deaths for one event calculated using millions of person-years be considered due to industrial activity (e.g. (the delayed deaths from a 1943 Liberator exposure for the whole NZ population ships carrying coal or used for industrial-scale air crash). Remaining differences with the (the issues around other denominators are fishing). Furthermore, while we classified work by Bradt et al. appear to result from detailed in the Discussion Section). the Ongarue train crash and the Tangiwai various methodological differences, e.g. their train crash as primarily being transportation- related, natural events were also implicated (a inclusion of other types of disasters with <10 Results fatalities, events outside of NZ territory, and storm-related landslide and a volcanic-related what seem to have been 18 events they did Types of events lahar (flow of mud or debris), respectively). not include (mainly less well-known ship The classification of five events as primarily A total of 56 events were identified and sinkings in the early 1900s). ‘war-related’ was also complex. These events summary details on each are in the were unusual in their characteristics, e.g. Supplementary Table (available online). The enemy mine explosions in NZ waters in World Data on cause, fatalities and inquiries results of our classification of the major event War I and a riot in a prisoner-of-war camp. These data were sourced from official cause are shown in Table 1 and this suggests Three of the five related to United States sources: either Te Ara (the Encyclopaedia of that most (64%) of events involved forms 10 military aircraft or naval vessels that were in NZ), the online official site New Zealand of transportation: especially ships (n=26), 11 NZ during World War II. History, or the official inquiry into the event. then aircraft (n=6) and trains (n=3). Next in NZ has many types of official inquiries,12 frequency were events classified as having but for simplicity we took the approach of predominantly natural causes (11%), which Mortality burden and trends not distinguishing between the different included three earthquakes, two volcanic The total mortality burden was 1,896 deaths with the most severe single event being the Table 1: Primary causes of the sudden mass fatality events identified (see text for multiple causal pathways Hawke’s Bay earthquake in 1931 (258 deaths). sometimes being involved). There was an average of 16.3 deaths per year Time period Transport Natural Industrial War Infrastructure Human Total over the period studied. Natural events had agency* the highest average mortality burden per 1900-1919 18 0 2 1 0 0 21 event (Table 2), but the standard deviations 1920-1939 4 4 1 0 0 0 9 were large. Earthquakes were the most lethal 1940-1959 7 0 0 4 2 0 13 natural event and there were three of these 1960-1979 5 1 1 0 0 0 7 with 460 deaths in total (4.0 deaths per year 1980-1999 1 0 0 0 1 1 3 on average).