Otira Valley on the South Island of New Zealand is a geologically active area. High erosion, uplift and rain lead to a lot of relief, high valleys and unstable slopes. These create frequent and intense landslides, posing serious threats to those who drive through this area. It is believed that there was one seismic event that caused the major destruction in this valley. 186 A.D. was the last major Taupo volcanic eruption, which probably had caused enough seismic energy and shock to initiate an epic landslide. Charcoal was found and dated back to 1900 BP, showing that the Taupo eruption could have a strong connection to the origin of the landslide. A viaduct was created in the valley to stabilize the road, as it previously built on top of a landslide. This project cost $25 million and was constructed over 2 years. This viaduct was created because it is well-resistant to earthquakes and is minimally affected by erosion from landslides. The viaduct can withstand earthquake stresses 40% more than all other forms of protection created in New Zealand. There are also V-supports that reflect landslide debris, these supports are visible on the 2 end piers, but not in the middle pier because this is not a big path for landslide debris. The overlying problem is that the alpine fault goes through this valley so it is very geologically active; this is one of the most tectonic areas in the world because of increased precipitation, uplift, and increased relief of unstable slopes. All of these characteristics make it very unstable and an area of concern, which is why the viaduct was created. A road was initially created in this unstable valley in the 1860s for transportation and took 18 months to create.

-By: Jordan Silletti