Scientists say it appears a typical roof on a New Zealand house can withstand flying volcanic rock during an eruption, but there's a catch.
The discovery comes as researchers wrap up an explosive study to help Auckland prepare for a volcanic disaster.
A group of Canterbury University scientists experimented, launching their own volcanic boulders onto a typical New Zealand roof to see how it would hold up during a volcanic eruption.
"There's about three to four tonne of ash on the roof, so it's all loaded up and we are close to the point of where we think it would actually collapse," says Canterbury University professor, Tim Wilson.
However, the roof doesn't collapse but holds. Wilson saying the ash cover "seems to be providing quite a considerable cushion for those ballistic strikes."
The Earthquake Commission-funded research is aimed at helping the insurance industry and other authorities better deal with a volcanic eruption and its aftermath in our biggest city.
"We've spent a lot of time in Chile and even places like Vanuatu and the Philippines where we observed buildings with a lot less ash on them and certainly ballistics collapsing at much lower thicknesses of ash, so it's great to see the New Zealand system holding up so well," Wilson says.
Auckland sits on an active volcanic field with 53 volcanic cones - the risk of eruption is low - only 5-15 per cent in a lifetime - but it will happen at some point.
Auckland activity is monitored around the clock.
"We'd be initially be looking for little earthquakes that show magma rising, which might tell us if it's on the way - but we don't know where it might come up in Auckland. It can come up in a new place everytime, anywhere in the Auckland field - which is pretty much anywhere in Auckland city," says Graham Leonard of GNS Science.
The next phase will see researchers turn up the heat, adding magma, hot rocks and lava flows to see how they hit.