December 10, 2023

Hawke’s Bay could continue to feel aftershocks for months following severe earthquake

Watch: Two severe earthquakes have shaken the North Island within minutes of each other.

Hawke’s Bay continues to shake after a severe earthquake hit, followed by a flurry of over 80 aftershocks.

But an expert has warned the tremors are expected to continue even into the coming months.

A severe earthquake followed by a significant aftershock shook the North Island within minutes of each other on Wednesday morning.

The first quake was magnitude 5.9 and struck near Pōrangahau in Hawke’s Bay at 10:19am. GeoNet categorised the 22km deep quake as ‘severe’. More than 22,000 people reported feeling the tremors.

A 5.4-magnitude aftershock in the same location struck about four minutes after the initial quake. It was 13km deep and also categorised as severe.

There was no tsunami threat from the quakes, National Emergency Management Agency confirmed. 

GNS Science duty seismologist Katie Jacobs said since the magnitude 5.9 earthquake more than 80 aftershocks have been recorded and there are likely more to come.

“This is an area that does experience frequent earthquake activity, and this number of aftershocks is typical for events of this magnitude,” Jacobs said in a statement to Newshub. 

“We can expect ongoing aftershocks which might be large enough to be ‘felt’ in the coming weeks to months, with decreasing likelihood over time.”

Pōrangahau, a small township in the southernmost part of Hawke’s Bay, is located along the Hikurangi Subduction Zone which drives much of the earthquake activity along the East Coast of the North Island.

The Hikurangi Subduction Zone runs offshore from the east of Gisborne down to the top of the South Island. A subduction zone is where one tectonic plate subducts or dives under another, and the boundary between the two plates forms a large fault.  

Jacobs said the region also experiences slow slip events. These are earthquakes that happen very slowly and are not felt, with energy that is released over weeks to months.

Jacobs said scientists are continually working to understand more about New Zealand’s seismic activity and subduction processes behind it.

“Some of these scientific investigations involve field work, and the deployment of additional sensors and equipment,” she said. 

“We’d like to thank all those people that help advance our scientific understanding by hosting our equipment and allowing us access to make observations.”

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