What Are Earthquake Swarms? 30 Seismic Events In Australia Reveal New Details

Seismic experts are raising concerns that long periods without earthquake activity could lead to complacency, following recent tremors in the Hunter region of New South Wales (NSW) and Western Australia’s (WA) wheatbelt.

Geoscience Australia reported more than 30 seismic events in NSW, including a 4.5 magnitude earthquake near Muswellbrook, just weeks after a 4.8 magnitude tremor near Denman. Similarly, WA’s wheatbelt has experienced a cluster of 30 or more quakes, some reaching magnitudes up to 4.4, near Wyalkatchem.

Adam Pascale, chief scientist at Victoria’s Seismology Research Centre, explained that earthquake swarms are a series of tremors in a particular area, which are different from typical earthquakes where aftershocks follow the main event.

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These swarms can occur anytime, anywhere, as the Earth releases accumulated tectonic stress. While swarms are often natural, certain human activities like mining can sometimes trigger seismic activity, according to Pascale.

Gary Gibson, a seismologist from the University of Melbourne, added that extracting resources can contribute to earthquakes, depending on the geology and fault lines.

Despite the sporadic nature of seismic activity in Australia, the country’s long history of minimal earthquakes has led to a degree of complacency. Gibson highlighted that although Australia’s earthquake frequency is low, the damage caused can be significant.

He noted that engineering standards for earthquake-resistant infrastructure vary globally, with countries like Chile being leaders in earthquake-safe construction. In Australia, the strength of the rocks and faults means a high level of stress is required for failure, raising potential risks.

While major infrastructure can be built to withstand some seismic activity, the cost is often higher. Pascale pointed out that nuclear power stations have been discussed in relation to these seismic events, given one was proposed near the affected areas.

As for predicting the end of the swarm, Gibson stated it’s difficult to determine. Earthquake swarms can last from days to months, with some smaller tremors potentially signaling a larger event. Pascale added that forecasting swarm activity is far more challenging than predicting typical earthquake sequences.