In the Australian outback, we’re listening for nuclear tests – and what we hear matters more than ever
- Written by Hrvoje Tkalčić, Professor, Head of Geophysics, Director of Warramunga Array, Australian National University
Tyres stick to hot asphalt as I drive the Stuart Highway from Alice Springs northward, leaving the MacDonnell Ranges behind. My destination is the Warramunga facility, about 500 kilometres north – a remote monitoring station I’ve directed for the Australian National University for nearly 19 years, and one of the most sensitive nuclear detection facilities on Earth.
When I started exploring Earth’s inner core in 1997, I had no idea my calling would lead me here, or that I’d spend years driving this highway through the red expanse of the Australian outback.
And today, as the New START treaty curbing the US and Russian nuclear weapons programs expires, the work we do in the red centre has become more important than ever before.
A giant telescope pointed at Earth’s centre
Located 37km southeast of Tennant Creek – or Jurnkkurakurr, as it’s known in the local Warumungu language – Warramunga consists of what might generously be called a demountable building, surrounded by sensors lined up across 20km of savannah, covered by red soil and long, white spinifex grass.
The facility operates two sophisticated arrays. One consists of 24 seismometers detecting vibrations through Earth, the other eight infrasound sensors picking up ultra-low-frequency sound waves inaudible to human ears.
When North Korea detonated its largest nuclear device in September 2017 – about 7,000km away – our instruments captured it clearly. Warramunga detected all six of North Korea’s declared nuclear tests, and our data was among the first to reach the International Data Centre in Vienna.
The geological stability and remoteness mean we detect events that might be masked elsewhere. When a wild brumby gallops past our sensors, we pick it up. When a nuclear bomb is tested on the other side of the world, we definitely know about it. We can distinguish it from an earthquake because of the different kinds of vibrations it produces.
Warramunga detects more seismic events than any other station in the global network. With multiple instruments in a carefully designed configuration, far from the coast and human activity, you have something like a giant telescope pointed at the centre of Earth.
An unusual partnership
Warramunga’s story began in 1965 when Australia and the United Kingdom jointly established it for nuclear test detection during the Cold War. In 1999, it was upgraded and later certified as a primary station in the Comprehensive Nuclear-Test-Ban Treaty Organization’s International Monitoring System.
The CTBTO, headquartered in Vienna, operates a global network of more than 300 facilities designed to detect any nuclear explosion anywhere on Earth. Australia hosts 21 of these facilities – the third-largest number globally.
But Warramunga is unique. It’s operated by a university on behalf of both the CTBTO and the Australian government, located on Warumungu Country. The location of sensors was determined in consultation with Traditional Owners to ensure the instruments would not interfere with sacred sites.
The Research School of Earth Sciences at the Australian National University in Canberra has managed Warramunga for more than 50 years, and we still do.
Life at the station
The station requires constant attention. Two dedicated technicians drive from Tennant Creek to the array each morning. By the time they arrive, the Sun is already high above the red land across which the array’s elements and termite mounds are spread.
They keep a careful watch on the world’s earthquakes and explosions, enduring extreme heat, dust, flies, fires, floods, thunderstorms and the occasional visit from wildlife. They ensure data flows continuously via satellite to Vienna.
After one infrastructure reconstruction, we found two large goannas wrapped around a seismometer, having decided to spend their nights in the firm embrace of our equipment. You don’t learn about this kind of challenge in Vienna’s United Nations offices.
From Canberra, I coordinate between the on-site team, the Australian government, and our partners at the CTBTO. At least once a year, I make the drive up the Stuart Highway to Warramunga, checking equipment and discussing challenges with the technicians.
I also meet regularly with colleagues at the United Nations in Vienna. Managing this facility means bridging two worlds: the practical realities of maintaining sensitive equipment in a harsh environment and the international diplomacy of nuclear verification.
Why it matters now
For more than 30 years, the world has observed a de facto moratorium on nuclear explosive testing. The last US test was in 1992. Russia’s was in 1990.
This norm has been crucial in limiting nuclear weapons development. Verification systems such as Warramunga make this possible, because would-be violators know any significant nuclear explosion will be detected.
But this system faces its greatest challenge in decades. In October 2025, President Donald Trump announced the United States would begin testing nuclear weapons “on an equal basis” with Russia and China.
Days later, President Vladimir Putin directed Russian officials to prepare for possible nuclear tests. If this moratorium collapses, it opens the door to a new era of nuclear arms racing.
This is when verification becomes most crucial. The CTBTO’s network doesn’t just detect violations – its existence deters them. If the world knows a country has carried out a nuclear test and tried (but failed) to hide it, the testing country will face political consequences.
A hidden contribution
Warramunga’s data also helps researchers understand earthquakes, study Earth’s deep interior, such as the solid inner core, and track phenomena from meteorite impacts to Morning Glory clouds – extraordinary atmospheric waves travelling 1,400km from Cape York, first scientifically documented with Warramunga’s infrasonic array in the 1970s.
What strikes me after nearly two decades is how this unique partnership represents a remarkable example of academic institutions contributing directly to global security.
Few people realise that a university research school operates one of the world’s most crucial nuclear verification facilities. It’s an arrangement that brings together fundamental scientific research with practical obligations under international treaties – a model for how researchers can engage with pressing global challenges.
As nuclear rhetoric intensifies globally, the quiet technical work in the Australian outback gains new significance. Nuclear test monitoring is essential to deter would-be nuclear nations – and that’s a mission worth maintaining, even from the remote red centre of Australia.
Authors: Hrvoje Tkalčić, Professor, Head of Geophysics, Director of Warramunga Array, Australian National University
