Short sharp shaking from minor quake

Night owls were rocking and rolling early yesterday after a small earthquake struck about 30km to the west of Dunedin.

GeoNet reported the magnitude 3.8 earthquake took place at 12.57am at a depth of about 5km and was centred just outside Lee Stream.

GNS Science seismic duty officer Jonathan Hanson said the shaking felt in Dunedin would have been relatively sharp, but short, consistent with a shallow event of this magnitude and distance.

Earthquakes in the region while not common, were not unexpected.

"Over the last 20 years there have been 15 shallow earthquakes greater than magnitude 3 around Dunedin.

"In 2014 and 2015 we had a magnitude 4 and a magnitude 4.7 in a very similar location to last night’s event."

University of Otago chair of earthquake science Prof Mark Stirling said the focal mechanism of the earthquake was known as a reverse fault event.

"It was where two blocks of rock, both sides of the fault move towards each other, they squeeze together and flip."

The size of the earthquake meant it was not large enough to cause any surface effects like breaks or ruptures.

While yesterday’s quake was not of major concern, it served as a reminder that Otago was not exempt from seismic activity and people should be prepared for the small chance of a major shake.

"People should in a general way be aware of the earthquake hazard ... and about the scenario ‘what if there was a major earthquake and we didn’t have water and transport’ and things like that.

"Preparedness is what I emphasise. You can’t do anything about it, but you can be prepared."

Add a Comment