Experts in New Zealand have developed new tools to predict the effects of liquefaction during earthquakes.

Professor Misko Cubrinovski and his team from the University of Canterbury say their work will improve analysis of liquefaction risk across different soil types and help the quake-prone nation make more resilient buildings.

Liquefaction occurs during quakes when water pressure in saturated soil causes the ground to lose strength and stability.

Professor Cubrinovski says it is one of the biggest seismic hazards in New Zealand, accounting for nearly 40% of economic losses during the 2010 Canterbury quakes, or about $NZ15 billion ($13.9 billion).

His team, funded by government insurer EQC Toke Tu Ake, have created specialist sampling techniques to retrieve soil samples while preserving their density, and used computer modelling to simulate how ground and structures might behave in liquefiable soil during quakes.

“The old methods did not reflect the interaction between different layers of soils that can increase damage to buildings in earthquakes, or in other cases actually prevent damage from liquefaction,” Professor Cubrinovski said.

He says the team focused on “vulnerable soils, like reclaimed land in Wellington Harbour, where we noticed a lot more damage to buildings than you might have expected in that level of shaking.

“Those high-quality soil samples gave us invaluable new insights around liquefaction.”

EQC risk reduction and resilience principal adviser Caleb Dunne says Professor Cubrinovski’s work will be vital in understanding New Zealand’s liquefaction risk.

“Being able to better predict how soil will behave in an earthquake will help New Zealand plan for future events – whether that’s reinforcing at-risk properties or choosing safer building sites,” he said.