News release

From: The University of New England

Research uncovers the trigger behind slow earthquakes

New research led by the University of New England’s Dr Timothy Chapman has uncovered the trigger behind slow earthquakes, providing valuable answers forthose living in disaster-prone areas.

Unlike regular earthquakes that cause sudden, quick movement, slow earthquakes are rarely felt, with seismic activity occurring over days and in some cases months.

Dr Chapman says these earthquakes follow a rhythmic, predictable cycle and only need a small force equivalent to the weight of a filled bathtub to rupture.

“This research explored how water becomes rapidly available from otherwise solid minerals in a cyclical fashion over thousands or millions of years,” he says.

“As the water is available in the pores of the rock it enables the low forces needed to induce slow earthquakes and can account for their repeated activity.”

To uncover this development, the research team travelled to New Caledonia to explore possible ‘fossil’ examples of slow earthquakes recorded in rocks on the Earth’s surface.

The samples were put under the microscope and analysed for tiny features that indicated water was once present.

By uncovering this information, scientists will be better equipped to prepare and minimise risk surrounding these elusive earthquakes.

“This research is important as billions of people live in regions at risk of earthquakes,” said Dr Chapman.

“Many more, including Australians, live along coastlines that can be impacted by earthquake-generated tsunamis.

“Improved understanding of how and why slow earthquakes do or do not occur is at the core of any hazard assessment.”

While this stage of the research has wrapped up, Dr Chapman says there is still much more that needs to be done.

“The next steps include assessing the scales of movement experienced in the rocks during these slow earthquake events,” he says.

“One of the challenges we face is that looking for these ‘fossil’ features is akin to finding a needle in a haystack due to the small duration of activity (days or months) in rocks formed over millions of years.

“Once found, these features need to be connected back to much larger scale forces within sequences of rock or upwards of an entire movement of a tectonic plate.”

The research has been published in the world’s top geoscience journal, Geology, and can be viewed here.