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  3. Q. How was the Hikurangi Trench created?

Q. How was the Hikurangi Trench created?

Hikurangi tectonic plate boundary

Answers to your Questions:

Q. How do tectonic plates move?

A. Tectonic plates move because they are floating on top of hot liquid rock (called the mantle) under the earth’s crust.  Big swirls of moving liquid rock jostle the tectonic plates on top and make them move.


Q. Can the plates break?

A. Tectonic plates are very thick and as far as scientists know they do not break.


Q. Why is it called Hikurangi?

A. Not sure! Perhaps in respect of our maunga Hikurangi 


Q. How was the Hikurangi Trench created?

A. The Hikurangi Trench was created by the Pacific tectonic plate subducting under the Australian tectonic plate.  The ocean plate (the Pacific Plate) is being pushed (converged) under the thicker Australian continent plate and as it is forced underneath it creates a big gully called a trench.  Because it is near land, this gully fills up with rubble (sand and silt – called sediment) and is quite shallow.  


Q. How far off-shore is the Hikurangi trench?

A. Along the East Coast the Hikurangi Trench is 60 - 90km from the coast


Q. How long does it take to travel back to shore from the trench?

A. It depends where you travel from, in some places the trench is close to shore and in other places it is further away.


Q. How long, how deep (underwater) and how wide is the trench?

A. The Hikurangi Trench is 2.5 – 4 kms deep.  It runs from Kaikoura in the South to Tonga in the North.


Q. Why is the research being done on the trench?

A. Tectonic plates are quite a new idea (first ‘discovered’ in the 1960s).  There is a lot that scientists would like to know about how they move and work.  As well it is good to have a lot of information about hazards (like earthquakes and tsunami) so we can be prepared.  Scientists think that some earthquakes at tectonic boundaries can be “mega-quakes” so the more we know about the Hikurangi Trench the better prepared we are for a big earthquake and possible tsunami.


Q. How many layers does the earth have?

A. The earth has four layers – the crust, the mantle, the outer and the inner cores. 


Q. Will New Zealand shape change after a while?

A. Yes.  New Zealand is intersected by two tectonic plates – the Pacific and the Australian plates.  As these plates continue to move past and into each other, New Zealand’s landscape will continue to change.