Looming Threat Beneath the Surface: Why Adelaide Faces Australia’s Highest Earthquake Risk
Despite a reputation for stable weather, Adelaide is quietly sitting atop a geological hotspot, making it the most earthquake-prone capital city in Australia. Experts warn a significant earthquake is almost inevitable, potentially within decades.
The City of Churches experienced its most damaging earthquake on March 1, 1954, a magnitude-5.4 event that injured three people and caused approximately 30,000 insurance claims related to over 3,000 damaged buildings – cracked walls, collapsed chimneys, and shattered windows were commonplace. A University of Adelaide newsletter captured the front page of The News newspaper on that fateful day, a stark reminder of the city’s vulnerability.
A Foreseeable Future of Seismic Activity
Professor Alan Collins, from the University of Adelaide’s Tectonics and Earth Systems, believes another major earthquake is “almost certainly” going to happen in his lifetime. “Whether it happens this year, or in 10 to 15 or 20 years, who knows, but it’s likely to happen in that sort of timeframe — so in the foreseeable future,” he stated. Estimates from the university’s School of Civil and Environmental Engineering suggest a repeat of the 1954 quake could inflict a billion dollars in damage today.
Adelaide: Australia’s Seismic Epicenter
Adelaide’s position as Australia’s most seismically active region is due to a complex network of faults running beneath the Greater Adelaide area. These include the Willunga fault to the south, the Para fault to the north, and the Eden-Burnside fault, which stretches from near Seacliff into the Hills Face Zone. Notably, a fault line even runs through Bonython Park towards Thebarton Theatre, a factor considered during the planning stages of the new Torrens to Darlington project tunnel.
The underlying cause stems from the Indo-Australian tectonic plate, which encompasses the Indian subcontinent and roughly half of New Zealand, shifting approximately 7 centimeters northeast each year. As this plate moves, it’s pushed by a ridge in the Southern Ocean and grinds against other plates, creating immense force. “We’re in a weak zone within that plate, so when the forces get big enough from us grinding into those other plates, the weak rocks under Adelaide break and we create the Mount Lofty Ranges,” explained Professor Collins.
The Mount Lofty Ranges themselves are a testament to this ongoing geological process, having been formed over three million years by earthquakes capable of raising the earth by one to two meters in short, powerful bursts. These movements aren’t always sudden; the ranges also experience a gradual upward creep due to the constant seismic activity.
A History of Shakes and Tremors
While the 1954 earthquake remains the most destructive in South Australia’s recorded history, the strongest was a magnitude-6.5 quake near Beachport in 1897. Reports from the time described widespread devastation, with the post office and telegraph station wrecked and “the earth opened in the main street.” A house in Wangolina was wrecked, injuring an infant.
More recently, Adelaide experienced a “cluster of events” in 2022, according to one senior seismologist. On April 16, 2010, a magnitude-3.8 earthquake centered near Mount Barker shook the Adelaide Hills and was felt as far away as Kangaroo Island. Geoscience Australia deemed this quake “larger than usual” for the region.
Increasing Frequency of Earthquakes
Recent data reveals a consistent level of seismic activity. South Australia has recorded 126 earthquakes this calendar year (as of December 10), including three above magnitude-4 – two southeast of Hawker and one in the Lake Eyre region. In 2024, 137 earthquakes were recorded, including a magnitude-4.2 at Jamestown and a magnitude-4.1 northwest of William Creek. Prior years saw 88 earthquakes in 2023, 78 in 2022, and 52 in 2021.
Geoscience Australia seismologist Jonathan Griffin notes this frequency isn’t necessarily indicative of an impending “big one.” “It’s a random thing, like the toss of the coin — sometimes you’ll get three heads in a row,” he said. However, he acknowledged that moderate to large earthquakes often trigger aftershocks, increasing the likelihood of further tremors in the short term. While foreshocks – earthquakes preceding a larger event – are possible, aftershocks are far more common.
Assessing the Risk and Preparing for the Inevitable
Despite the potential for significant damage, the Department of Planning, Transport and Infrastructure classifies Adelaide’s earthquake risk as “low to moderate” on a global scale. However, the department emphasizes that, “by Australian standards, Adelaide has the highest risk of all capital cities.” Seismologists advise that earthquakes up to magnitude 7.5 are possible in South Australia.
The 2019 DPTI pamphlet highlighted the Mount Barker earthquake as a reminder of the need for critical infrastructure owners and managers to consider seismic activity in their planning. It’s a sobering thought, especially considering the 1989 Newcastle earthquake – a magnitude-5.6 event – resulted in 13 deaths and 160 hospitalizations. While smaller than the potential magnitude Adelaide faces, the Newcastle disaster underscores the devastating consequences even moderate earthquakes can have.
The geological reality is clear: Adelaide’s location makes it uniquely vulnerable to earthquakes. While predicting the exact timing remains impossible, the scientific consensus points to a significant seismic event occurring in the foreseeable future, demanding continued vigilance and proactive preparation.
