Queensland mining data informs better understanding of underground stresses

Australia Broadcast Center

4 days ago

New research into the world's tectonic plate stress patterns has led to a better understanding of how the mining and construction industry affects what goes on beneath the Earth's surface.
The latest World Stress Map, released this week, revealed new earthquake trigger data and information about how stress builds in the Earth's crust as a result of underground mining activity mapped in Queensland's Bowen Basin.
Mojtaba Rajabi, from University of Queensland's (UQ) School of Environment, said the latest update to the map could help make underground mining and construction activities safer by providing better insights into the Earth's stress conditions.
"Digging, drilling or injecting fluids in the wrong spot can tip the underground balance and induce a seismic event.
"Understanding stress helps us prevent these man-made shakes."
Through UQ's collaboration with Germany's GFZ Helmholtz Centre for Geosciences, the Earth's underground stress patterns have been mapped in more detail than ever before.
Dr Rajabi said the latest update included more than 100,000 stress data records.
"This is almost double the data from the previous release we published in 2016," he said.
The new data from central Queensland's mining heartland, the Bowen Basin, has found a dramatic rotation in underground stress of more than 50 degrees within 100 kilometres.
Dr Rajabi said the mining data, which was analysed remotely, would lead to pinpointing vulnerable areas that could potentially trigger earthquakes.
"The direction of the tectonic force coming from the plates east of Australia change dramatically, and when these forces interact with local geological conditions they redirect stress in different ways," he said.
"As a result, the safest directions for drilling and excavation can vary significantly between locations in the same region.
"This gives us a really great guide on ways we can dig safer in terms of mining or reservoir analysis studies, such as in our gas exploration."
The Queensland Mining and Energy Union said the new data would be a vital tool for researchers and industries working to ensure the safe use of the Earth's sub-surface.
Mining health and safety representative Jason Hill said it had the potential to help coal mines with strata control — a method used to maintain the stability of the ground.
"Strata control is a principal hazard and it has killed a lot of people over the years, so any data or research into the management of strata is very much welcome," he said.
Mr Hill said he hoped mining operators would adopt the findings.
"The most important thing now is the companies actually take a look at [the report] and use it to ensure that they are achieving an acceptable level of risk," he said.
The World Stress Map has been updated every decade for more than 40 years, drawing on data from seismology centres, the energy and resources sector and civil engineering projects across the globe.
Dr Rajabi said Australia's underground stress patterns were unlike any other continent.
"Highly variable, full of twists and turns, and not aligned with the direction the continent is moving," he said.
"With this [new] level of detail, we can now better understand how tectonic forces behave not just across regions but at the local scale too."