Key Takeaways
- Adelaide is considered the most earthquake-prone of Australia’s capitals, with a history of significant seismic activity.
- The city’s last major earthquake, which occurred in 1954, resulted in significant damage and injuries, and experts predict that another big one is likely to happen in the foreseeable future.
- Adelaide sits atop the Indo-Australian tectonic plate, which moves about 7 centimeters north-east each year, contributing to the region’s seismic activity.
- The city has several active fault lines, including the Willunga fault, the Para fault, and the Eden-Burnside fault, which increase the risk of earthquakes.
- Experts estimate that if a repeat of the 1954 earthquake were to occur, it would cause around $1 billion in damage.
Introduction to Adelaide’s Seismic Activity
Adelaide is often considered to have a stable climate, but beneath the surface, the city is at risk of significant seismic activity. In fact, Adelaide is the most earthquake-prone of Australia’s capitals, with a history of destructive earthquakes. The city’s last major earthquake occurred in 1954, resulting in three serious injuries, damaging over 3,000 buildings, and leading to around 30,000 insurance claims. According to Professor Alan Collins from the University of Adelaide’s Tectonics and Earth Systems, another big earthquake is likely to happen in the foreseeable future, although the exact timing is uncertain.
The Geology of Adelaide
Adelaide sits atop the Indo-Australian tectonic plate, which includes the Indian subcontinent and about half of New Zealand. The plate moves about 7 centimeters north-east each year, contributing to the region’s seismic activity. The city has several active fault lines, including the Willunga fault, the Para fault, and the Eden-Burnside fault, which increase the risk of earthquakes. Professor Collins notes that the Mount Lofty Ranges have been constructed over about three million years by earthquakes, which can push the earth upwards by one to two meters in short bursts of power.
Historical Earthquakes in Adelaide
While the 1954 earthquake remains the state’s most destructive on record, its strongest was a magnitude-6.5 earthquake near Beachport in 1897. The earthquake caused significant damage, including the wrecking of a house and the injury of an infant. More recently, Adelaide experienced two notable earth tremors in one month during 2022, and in 2010, a magnitude-3.8 earthquake occurred in the Adelaide Hills, shaking houses from the hills to the coast. According to Geoscience Australia, South Australia has experienced 126 earthquakes this calendar year, including three above magnitude-4.
The Risk of Future Earthquakes
Experts predict that Adelaide will experience another big earthquake in the foreseeable future. The Department of Planning, Transport and Infrastructure states that Adelaide’s earthquake risk is "low to moderate" on a global scale, but by Australian standards, the city has the highest risk of all capital cities. Seismologists advise that earthquakes up to Richter Magnitude 7.5 can occur in South Australia. Geoscience Australia seismologist Jonathan Griffin notes that while there is no real reason for having a greater or lower number of earthquakes on average in the region, the city’s high level of seismic activity means that residents should be prepared for the possibility of a significant earthquake.
The Potential Impact of a Major Earthquake
If a repeat of the 1954 earthquake were to occur, experts estimate that it would cause around $1 billion in damage. The University of Adelaide’s School of Civil and Environmental Engineering estimated in 2011 that a repeat of the 1954 earthquake would have a significant impact on the city’s infrastructure and economy. The Department of Planning, Transport and Infrastructure notes that the Mount Barker earthquake was a reminder that earthquakes need to be a consideration for critical infrastructure owners and managers in the state. As such, it is essential for residents and authorities to be prepared for the possibility of a significant earthquake and to take steps to mitigate its impact.