How will Auckland’s underground cables cope with an eruption
20 June 2018
Hot or not? How will Auckland’s underground cables and pipes cope in a volcanic eruption?
With eyes on Hawaii’s Kīlauea volcano, a local researcher is asking how Auckland's underground water pipes and power cables would cope if lava cut over their pathway.
Sophia Tsang, an EQC-funded student researcher at University of Auckland conducted tests at the end of last year at Syracuse University’s Lava Project in the USA and is in the final stages of answering the question.
"Syracuse University is the only place in the world you can do these kinds of tests on a large scale. The furnace heats rocks to 1300 degrees Celsius, above the melting point of basalt, which is the type of rock that Auckland’s volcanos produce.
“I used basalt to make pāhoehoe lava flows, one of the types of lava flows that we are likely to get in Auckland, and tested it over Auckland-type soil, asphalt roads and concrete footpaths – which are where a lot of our infrastructure is buried.”
To measure the heat effect, Sophia and the team buried temperature probes in the ground at various depths, before pouring lava of different thicknesses over the area.
"It was really exciting being so up close with lava. I've been to Hawaii and seen natural lava flows in the field, but what you don't commonly see in the field, is how the ground actually reacts under the lava.
"What we’ve found so far in our testing is that at one metre thick, the Auckland-type lava barely affected the ground past 40cm deep. But of course, if we get an eruption in Auckland, the lava flow could be a lot thicker and flow for longer than in my experiment,” she says.
"I’ve taken my results from the Lava Project to begin estimating temperatures under larger lava flows, which will allow researchers and companies that provide essential services to assess how a lava flow could impact Auckland’s underground pipes and cables.
Sophia’s preliminary results suggest that Auckland’s key infrastructure is likely buried deeply enough that it would not be impacted during a short eruption. She says that the length of time the lava flows could change that.
“The length of time the lava flow is active strongly controls how much heat is transferred into the ground below,” she says.
EQC Research Manager Richard Smith says Sophia's research will be a great addition to research on reducing the impact of a volcanic eruption on Auckland.
“Communities rely on infrastructure to keep functioning after a natural disaster. Even if your house is undamaged, you will only be able to stay there if you have services like water, sewerage and power. Research like Sophia’s helps understand what could happen to infrastructure in a volcanic eruption now, and also help planners working on future projects avoid these kinds of hazards,” says Dr Smith.
Sophia says that damage to pipes and cables is definitely something other places, such as Hawaii, have been concerned about during eruptions, as underground pipes and cables could heat up, potentially meaning limited water, sewerage and power service to parts of a city.
“In 2014 Department of Water engineers in Hawaii had to locate and install valves to minimise the number of customers affected by a lava flow and we’re keeping a close eye on what happens to water supply during the current Kīlauea eruption.”
Now that Sophia has gathered temperature data from under mini lava flows and created a model to estimate the heat transfer from lava flows into the soil below, her research will focus on determining where lava would flow in a series of eruptive scenarios developed by the Determining Volcanic Risk in Auckland (DEVORA) research programme. She will then take her work from the Lava Project to investigate potential impacts to buried infrastructure for the scenarios she models.
"These results will help planners and infrastructure providers reduce the risk of water, sewerage and power failing across a wide area if there is a lava flow. And with Auckland built on 53 volcanoes, it's something we need to think about,” she says.
Sarah Sinclair, Acting Director of Auckland Emergency Management, says that this research will be used to help with emergency planning.
“Knowing how our city and its infrastructure would cope in the aftermath of a volcanic eruption is critical. This kind of information is helping us to plan and build resilience and it’s important that we all think about these things. While it might seem daunting, planning for a volcanic eruption is no different to planning for any other disaster – have a talk with your loved ones and make a plan.”
DEtermining VOlcanic Risk in Auckland (DEVORA) is a collaborative research programme led by volcanologists at the University of Auckland and GNS Science and funded by EQC and Auckland Council. The project, now in its tenth year, aims to improve understanding of volcanic hazard and risk in Auckland. The findings have the potential to improve business decision-making and risk management, as well as make Auckland a safer place. To hear about the programme’s latest research, you can visit DEVORA’s webpage, or follow their Facebook page.
Funding for Sophia's research comes from EQC's annual $16 million funding for research to reduce the impact of natural disaster on people and property.