East Coast and the Hikurangi tectonic plate boundary
Here on the East Coast, we are close to the Hikurangi tectonic plate boundary which lies just off the coast. This is the boundary between the Australian plate and the Pacific plate.
The Hikurangi tectonic plate boundary is a convergent boundary. This means that the Australian and Pacific plates are pushing against each other. There are two kinds of plates – oceanic and continental plates. When oceanic and continental plates meet, the denser oceanic plate moves under the less dense continental plate. The Australian plate is a continental plate and the Pacific plate is an oceanic plate. At this boundary, the Pacific plate is slowly moving under the Australian plate. This process is called subduction.
Subduction zones are a type of fault and are responsible for the largest and most powerful earthquakes and tsunamis in the world. The Hikurangi subduction zone is potentially the largest source of earthquake and tsunami hazard in New Zealand, but there is still much to learn about it as we don’t know how often these earthquakes tend to happen, nor do we know how large they can be.