A powerful 5.3 magnitude earthquake that struck the lower North Island on Tuesday night was likely an aftershock of a 2014 quake in the same region, according to a GNS Science expert.
The earthquake, centred 10 kilometres east of Eketāhuna at a depth of 35km, was widely felt across the North Island. More than 20,000 people reported experiencing the shake, which occurred at 11:26pm. Reports of the tremor came from as far north as Doubtless Bay and as far south as Lake Manapōuri, with the strongest effects recorded in the central and lower North Island.
GNS Science principal scientist Dr Bill Fry explained that aftershocks from the magnitude 6.2 Wellington Anniversary Day earthquake in 2014 could continue for years.
“Because of the way tectonic plates move together, those disturbances take some time to play out, to redistribute themselves,” Fry said. “People will likely feel more shakes in the coming weeks and months.”
Despite the potential for further tremors, Fry noted that the likelihood of a significantly larger earthquake resulting from this event was low. “Earthquakes are unpredictable. There’s always a possibility of something bigger happening, but that’s not the typical way it evolves.”
Tuesday’s quake was notable for its intensity, with Fry suggesting it may have occurred within the Pacific Plate beneath the North Island, which could explain the sharp, jolting sensation experienced by many. Another possibility is that it originated in the “mega-thrust” fault, which separates the Pacific and Australian plates, though further analysis is needed to confirm this.
Earlier in the evening, two smaller earthquakes were recorded in the North Island. A 2.6 magnitude tremor struck 15km east of Stratford at 9:56pm, followed by a 2.4 magnitude quake 6km deep in Masterton at 10:38pm.
Fry noted that pinpointing exact causes for smaller quakes remains challenging. “We don’t fully understand the state of stress at depth, because we can’t actually touch it,” he said.
Residents are advised to remain prepared for further aftershocks in the coming weeks.
