submergence of Zealandia at c. 23 Ma (earliest Miocene) there may not have been any land in the area now occupied by New Zealand (Campbell and Hutching, 2007; Landis et al., 2008). Since the Miocene New Zealand has been pushed up and Zealandia divided into northern and southern crustal plates so creating the Alpine Fault and subduction zones beneath Fiordland and eastern North Island. Extent of New Zealand The 'Extended Continental Shelf' (ECS) of New Zealand lies within the submarine boundary, recognised by the United Nations, that delineates sovereignty over the seabed spanning from 159°E-166°W, and 23-58°S (Figure 1). The offshore area of New Zealand is c. 24 times its land area. The land area of 267,707 km 2 , is about the same size as the United Kingdom or Japan. The highest point above sea level is 3,754 m (Mount Cook/Aoraki) and the lowest point (onshore) is 462 m below sea level (bottom of Lake Hauroko). New Zealand consists of the North and South islands that are separated by the 20 km wide (minimum) Cook Strait, Stewart Island and subantarctic Auckland, Campbell, Snares, Antipodes and Bounty islands to the S, the Chatham Islands to the E, the Kermadec Islands to the N, and a host of tiny islands proximal to the two main islands. New Zealand is more than 1,600 km long and up to 450 km wide, with a coastline of more than 18,000 km. About 75% of the land is over 200 m above sea level. In the South Island 223 named peaks are more than 2,300 m above sea level. New Zealand on a plate Most of New Zealand lies NE-SW, reflecting the principal 'grain' of the country, parallel to and straddling the active segment of the Pacific-Australian plate boundary. The plate boundary (Figure 2) runs down the eastern side of the North Island, some tens of kilometres offshore, and is defined by the Tonga-Kermadec Trench and Hikurangi Trough. The North Island is on the Australian Plate. The boundary swings around the SE end of the North Island and cuts through the northern half of the South Island along the Hope Fault (Rattenbury et al., 2006). The Wairau, Awatere, Clarence faults are active sub-parallel faults in this Marlborough region but the Hope Fault is most active and the best proxy for the boundary. The Hope Fault runs along the southern margin of the Seaward Kaikoura Mountains inland towards Hanmer Springs, to cross the Southern Alps where it joins the Alpine Fault near Inchbonnie on the West Coast of the South Island. The Alpine Fault can be traced on land from the entrance of Milford Sound at its southern end, to Tophouse near Lake Rotoiti. It continues to the Cook Strait coast as the Wairau Fault. South of Milford Sound, it skirts around New Zealand is renowned for its diverse geology and dynamic tectonic setting astride an active segment of the boundary between the Pacific and Australian plates. New Zealand is an emergent fraction (5%) of the largely submerged 'continent' of Zealandia which is half the size of Australia. Zealandia is comprised mainly of continental crust but because it is less than 30 km thick, it ...
