Aftershocks from earthquakes near Milford Sound could last for days - seismologist

A series of earthquakes struck near Milford Sound on Wednesday night, with aftershocks potentially lasting for days, according to a seismologist. The tremors began around 6:16 pm local time, starting with a 5.5 magnitude quake, followed by a slightly stronger 5.6 magnitude shock just over 40 minutes later. Additional smaller quakes followed, measuring 4.8, 4.6, and 3.8 magnitudes, occurring shortly after the initial events. These quakes were centered approximately 40 kilometers northeast of Milford Sound, a popular tourist destination in New Zealand’s South Island. The sequence of tremors has raised concerns among residents and visitors in the area. Sam Taylor Offord, a representative from Earth Sciences NZ, noted that frequent aftershocks were observed during the late evening hours. He warned that smaller shocks might persist for several days, emphasizing that while the current activity does not indicate an immediate threat of a major disaster, vigilance is necessary. Offord explained that the quakes were not powerful enough to trigger landslides within the fiord or generate a tsunami, which alleviates some fears related to coastal safety. The location of the quakes, approximately 15 to 20 kilometers from the plate boundary, suggests they occurred along a less active fault system compared to the more notorious Alpine Fault. Although the type of tectonic movement observed was similar to that associated with the Alpine Fault, the depth and orientation of the faults involved differ significantly. This distinction is crucial in assessing the likelihood of future large-scale seismic events in the region. Residents living near the epicenter have been advised to remain cautious, particularly when the ground shakes. Offord recommended moving away from steep or unstable slopes during tremors to avoid potential hazards such as falling rocks or structural damage. While the immediate danger appears low, the ongoing activity serves as a reminder of the dynamic geological environment in the area. Local authorities and emergency services have been monitoring the situation closely. They have not issued evacuation orders but have encouraged individuals to stay informed through official channels. The Department of Conservation has also reminded visitors to the Fiordland National Park to exercise caution and follow guidelines regarding safe travel practices in the region. As the aftershocks continue, scientists will likely conduct further analysis to determine whether this sequence represents a minor episode or part of a larger pattern. The data collected from these quakes will contribute to a better understanding of seismic behavior in the area, helping to improve predictive models and preparedness strategies for future events. For now, the focus remains on ensuring public safety and maintaining communication with affected communities.