Climate change could challenge the downward trend of large-scale fatal disasters in New Zealand.

A University of Otago study in Wellington analysed sudden events in New Zealand between 1900 and 2015 that caused at least 10 deaths.

Its findings were published in the Australian and New Zealand Journal of Public Health.

It found a sharp drop in the number of fatal large-scale events, from 21 between 1900 and 1919, to just three between 2000 and 2015.

It also found that earthquakes were our most lethal natural disaster, with an average of four deaths a year over the 115-year period covered by the study.

Public health researcher Professor Nick Wilson, who led the research with associate professor George Thomson, put the drop down to safer transportation.

People had found much safer ways of getting around, he said.

"They were largely driven by the reduction in transport-related events. So, ships sinking, trains crashing, aircraft crashing.


"This transportation category reduction probably reflects a large number of factors, such as improvements in vehicle design, marine and aircraft navigation systems, weather forecasting and safety systems in general."

But the downward trend may not last forever, Wilson said.

"In the future, it's still uncertain, because climate change does seem to be happening rapidly.

"So there could even be those sort of risks that New Zealand has to think about in the future."

There were 56 sudden mass casualty disasters in New Zealand during the 115-year period covered by the study, Wilson said.

"We discovered 18 more events than reported previously, partly due to the identification of less well-known ship sinkings.

"There were 1896 deaths in total from these events, with the Hawke's Bay earthquake of 1931 having the highest death toll [258 deaths]."

Three earthquakes killed 460 people - an average of four deaths a year.

But in Australia, disasters have increased since the 1980s, peaking between 2005 and 2009, mainly because of bushfires and floods.

"If future climate change continues to be rapid, these types of events, along with mass deaths in heatwaves, could become more relevant in New Zealand as well," Wilson said.

New Zealand's 10 deadliest disasters 1900-2015

1. Hawke's Bay earthquake, 1931: 258 deaths
2. Crash of Air New Zealand flight TE901 into Mt Erebus, 1979: 257 deaths
3. Christchurch earthquake, 2011: 185 deaths
4. Tangiwai train crash following lahar from volcanic activity, 1953: 151 deaths
5. Sinking of the SS Penguin in heavy seas near Wellington, 1909: 75 deaths
6. Cyclone Giselle and the sinking of the Wahine inter-island ferry, 1968: 53 deaths
7: Featherston prisoner-of-war camp riot, 1943: 49 deaths
8. Sinking of the SS Elingamite off the Three Kings Islands, 1902: 45 deaths
9. Ralph's Mine explosion in Huntly, 1914: 43 deaths
10. Ballantyne's department store fire in Christchurch, 1947: 41 deaths