ANU Hidden Gems – Between a rock and a hard place

27 November 2017

A machine invented in the 1960's, and still at the forefront of ANU research in the field of Rock Physics, has recently celebrated its 50th birthday.

Dubbed 'the Paterson rock deformation apparatus', the machine was designed to measure and understand the strength and deformation processes in earth materials at conditions equivalent to those deep in the Earth's crust and underlying mantle, where temperatures can be as high as 1,000°C.

Built largely in-house at ANU by technical staff and overseen by geophysicist, Emeritus Professor Mervyn Paterson, the 'Paterson apparatus' still provides mechanically precise readings for rock experiments conducted under high pressures and temperatures.

Professor Stephen Cox, who has worked alongside Professor Paterson and the apparatus for many years, took us on a tour into the basement of the building at the Research School of Earth Sciences where it's kept.

"An interesting feature about the apparatus is that Professor Paterson originally designed it to explore slow plastic deformation that occurs deep in the Earth's crust," Professor Cox said.

"These experiments lasted hours to days and simulated processes that took millions of years in nature."

PhD student Kathryn Hayward is the latest researcher to use it, modifying the apparatus to study the incredibly fast deformation processes associated with an earthquake slip.

"In our current research, newly-developed technology is being used to record earthquake slip events lasting as little as a few milliseconds. Development of the new technology allows data sampling on microsecond timeframes," she said.

A demand for similar high-pressure, high-temperature rock deformation apparatus overseas led to Professor Paterson designing a commercial version in the 1980s. As a result, 12 machines were sold to labs in the UK, France, Germany, Switzerland, the US and China. More recently, Emeritus Professor Paterson has made his designs freely available to be archived and used in institutions in Europe and the USA.

As for the ongoing research with the upgraded Paterson apparatus?

"The machine continue to provide fundamental new insights about processes controlling whether earthquake slip events grow to become large, damaging events, or die out as small, inconsequential "micro-earthquakes", Kathryn said.

You can read more about this remarkable machine and the man who created it 50 years ago, on the Research School of Earth Sciences' publication page On Circulation.