A 4.1-magnitude earthquake that struck Muswellbrook in New South Wales on Tuesday is likely part of an ongoing “earthquake swarm” that could result in hundreds, if not thousands, of small to moderate tremors over the coming months, according to a seismologist from Geoscience Australia.
The shallow quake, which occurred around midday at a depth of just 3 kilometers, marks the fourth seismic event of magnitude 4.0 or greater in the Hunter region in the past three months. In late August, a 4.7-magnitude quake hit Muswellbrook, causing damage to homes and businesses.
Hadi Ghasemi, senior seismologist at Geoscience Australia, explained that the region is experiencing a series of moderate seismic events that are happening in close proximity both in time and location. These types of “earthquake swarms” could continue for months.
“We’ve already seen four magnitude-4 or larger quakes in the area,” Ghasemi noted. “These swarm sequences can involve hundreds to thousands of smaller to moderate shocks.”
Ghasemi described “moderate” shocks as earthquakes with magnitudes of 5.0 or lower, which may cause damage such as cracks in walls, items falling off shelves, and strong ground shaking for people near the epicenter.
The recent quake left approximately 2,500 homes and businesses in Muswellbrook without power. According to Geoscience Australia’s map, the epicenter was near the Mt. Arthur coalmine, just outside the town.
A BHP spokesperson confirmed there were no injuries following the earthquake and that mining operations had temporarily paused for a site inspection.
While it’s unclear whether the earthquake was directly linked to mining activity, Ghasemi pointed out that mines are often located on fault lines, which are naturally formed due to mineral deposits. He said that while some seismic activity can be induced by mining—due to the removal of large volumes of rock—there isn’t enough information yet to determine if this quake was a result of such activity.
“Mines are typically constructed on ancient faults because those faults often host the mineral deposits,” Ghasemi said. “Seismicity can sometimes be induced by mining, but it’s still too early to say with certainty whether this earthquake was triggered by the mining activities at Mt. Arthur.”
The region may also face further tremors, as earthquake swarms often continue for months, potentially impacting local communities.
In related news, Peter Dutton, leader of the opposition, announced that if his party wins the upcoming election, they plan to build a nuclear reactor in Liddell, located less than 20 kilometers from Muswellbrook.
