New Zealand's Hidden Megathrust Fault | Discovery Geology

So here we are at Tarakarai Head on the south coast of New Zealand's North Island and here we can see stunning physical evidence of past large earthquakes I'm standing on a gravel ridge and among these stones we see fossil shells that tell us this ridge was once down by sea level So we can see in these images a whole series of these lines along the coastline of bare rock and each of these lines represents a raised beach The beach we are standing on right now was actually raised in a massive magnitude 8.2 earthquake on the Wairarapa Fault in 1855 AD It raised this part of the coastline by 6.4 meters The horizontal movement was 16 meters along a 120-kilometer length of fault line This earthquake also triggered a massive tsunami that was 10 meters high So is this one of the largest events we could ever see in New Zealand No because actually right beneath me here is New Zealand's largest fault About 20 kilometers down is the Hikurangi subduction zone and this marks the boundary where the Pacific Plate It meets the Australian Plate and they crash together The Pacific Plate is actually being pushed down beneath the Australian Plate creating a giant fault surface These subduction zone boundaries cause the largest earthquakes and tsunamis that we've ever seen around the world For example in Japan in 2011 and in Sumatra in 2004 Here in New Zealand this fault extends across the entire eastern North Island from Marlborough in the south to East Cape in the north It's vital for us to better understand this zone To deal with the hazards it poses to us The New Zealand Government has funded a five-year research program to really delve into some of these questions We want to investigate how the plates are moving right now We want to know the structure of the plates and how they are interacting We also want to look at past earthquake records like we see here Where have these earthquakes occurred How big have they been And what other hazards such as tsunamis and landslides have they triggered