Home Energy Magnitude 6.2 earthquake hits New Zealand
Magnitude 6.2 earthquake hits New Zealand GeoNet

New Zealand was hit by a 6.2 magnitude earthquake on Tuesday afternoon. Very unusually for New Zealand, this quake was very deep, yet still very strong, and in a somewhat unexpected location.

This earthquake was centred about 25km southwest of Taumarunui, a regional town approximately 200km south of Auckland.

There were a few unusual features. Firstly the depth — 207km — is quite rare for New Zealand, and most earthquakes of that depth occur around the Fiordland area of southwest South Island, not in the west of the North Island.

Beyond that, reports of where (and where not) it was felt vary very widely with some close-by locations not noticing it – a local government councillor just a few tens of kilometres away reported feeling nothing, yet there were strong reports from Christchurch around 500km away.

This earthquake appears to be the result of the Pacific ocean floor being subducted under the North Island. The quake's location is approximately 300km from the subduction zone (running parallel to the eastern coast of North Island) and with typical subduction angles of about 30 degrees, the geometry is about right. There is an excellent summary of the process here. Observe that the volcanic action takes place relatively close to the subduction zone (as is true in New Zealand – with the geothermal zone to the east of this current earthquake). Most volcanoes of this type are due to the super-heating of water held within the seafloor sediments – it has to escape somehow!

Generally, major earthquakes related to subduction zones are caused by "lumps and bumps" on the seafloor which struggle to slide past the lithosphere above – eventually they move with a big 'shock' hence the earthquake. Readers may observe that many of the very large earthquakes occurring along the Chilean coast can be matched with chains of undersea volcanic peaks – these have a major difficulty sliding under the South American plate.

The variability in perceived strength of the quake is due primarily to the depth, but this is tempered by various obstacles and free-flowing zones in the crust above which can guide and concentrate (or disseminate) the earthquake waves – much like the perceived signal strength of a far-off radio station where driving a short distance can yield stronger and weaker signal with no obvious reason.

No significant damage has been reported – this is entirely typical of deep volcanoes. In addition, there was no tsunami warning – the only time a tsunami can occur is when the earthquake is shallow, under water and includes vertical movement of the sea bed - none of those were true in this instance. 

CDAO SYDNEY TURNS 5 IN 2019

With 50+ Speakers, 300+ senior data and analytics executives, over 3 exciting days you will indulge in all things data and analytics before leaving with strategic takeaways that will catapult you ahead on your journey

· CDAO Sydney is designed to bring together senior executives in data and analytics from progressive organisations
· Improve operations and services
· Future proof your organisation in this rapidly changing technological landscape
· CDAO Sydney 2-4 April 2019
· Don’t miss out! Register Today!
· Want to find out more? Download the Agenda

REGISTER HERE!

LEARN HOW TO REDUCE YOUR RISK OF A CYBER ATTACK

Australia is a cyber espionage hot spot.

As we automate, script and move to the cloud, more and more businesses are reliant on infrastructure that has the high potential to be exposed to risk.

It only takes one awry email to expose an accounts’ payable process, and for cyber attackers to cost a business thousands of dollars.

In the free white paper ‘6 Steps to Improve your Business Cyber Security’ you’ll learn some simple steps you should be taking to prevent devastating and malicious cyber attacks from destroying your business.

Cyber security can no longer be ignored, in this white paper you’ll learn:

· How does business security get breached?
· What can it cost to get it wrong?
· 6 actionable tips

DOWNLOAD NOW!

 

Popular News

 

Telecommunications

 

Sponsored News

 

 

 

 

Connect