The South Island, with an area of , is the largest landmass of New Zealand; it contains about one-quarter of the New Zealand population and is the world's 12th-largest island. It is divided along its length by the Southern Alps, the highest peak of which is Aoraki / Mount Cook at , making it 9th-highest island, with the high Kaikōura Ranges to the northeast. There are eighteen peaks of more than in the South Island. The east side of the island is home to the Canterbury Plains while the West Coast is famous for its rough coastlines such as Fiordland, a very high proportion of native bush, and Fox and Franz Josef Glaciers. The dramatic landscape of the South Island has made it a popular location for the production of several films, including The Lord of the Rings trilogy and The Chronicles of Narnia: The Lion, the Witch and the Wardrobe. It lies at similar latitudes to Tasmania (an island south of the Australian mainland), and parts of Patagonia in South America.
Geology and earthquakes
On 4 September 2010, the South Island was struck by a 7.1 magnitude earthquake, which caused extensive damage, several power outages, and many reports of aftershocks. Five and a half months later, 22 February Christchurch earthquake of 6.3 magnitude caused far more additional damage in Christchurch, resulting in 181 deaths. This quake struck at about lunchtime and was centred closer at Lyttelton, and shallower than the prior quake, consequently causing extensive damage.
The Alpine Fault runs through most of the South Island, The last major earthquake on the fault was in 1717, and it is likely that another one will occur in the next fifty years. Previous earthquakes have also occurred on the Apline Fault.
Climate
The climate in the South Island is mostly temperate. The mean temperature for the South Island is . January and February are the warmest months while July is the coldest. Historical maxima and minima are in Rangiora, Canterbury and in Ophir, Otago.
Conditions vary sharply across the regions from extremely wet on the West Coast to semi-arid in the Mackenzie Basin of inland Canterbury. Most areas have between of rainfall with the most rain along the West Coast and the least rain on the East Coast, predominantly on the Canterbury Plains. Christchurch is the driest city, receiving about of rain per year while Invercargill is the wettest, receiving about . The southern and south-western parts of South Island have a cooler and cloudier climate, with around 1,400–1,600 hours of sunshine annually; the northern and north-eastern parts of the South Island are the sunniest areas and receive about 2,400–2,500 hours.
Climate data
Climate change
Natural geographic features
Fiords
The South Island has 15 named maritime fiords which are all located in the southwest of the island in a mountainous area known as Fiordland. The spelling 'fiord' is used in New Zealand rather than 'fjord', although all the maritime fiords use the word Sound in their name instead.
A number of lakes in the Fiordland and Otago regions also fill glacial valleys. Lake Te Anau has three western arms which are fiords (and are named so). Lake McKerrow / Whakatipu Waitai to the north of Milford Sound / Piopiotahi is a fiord with a silted-up mouth. Lake Wakatipu fills a large glacial valley, as do lakes Hakapoua, Poteriteri, Monowai and Hauroko in the far south of Fiordland. Lake Manapouri has fiords as its west, north and south arms.
The Marlborough Sounds, a series of deep indentations in the coastline at the northern tip of the South Island, are in fact rias, drowned river valleys.
Glaciers
Most of New Zealand's glaciers are in the South Island. They are generally found in the Southern Alps near the Main Divide.
An inventory of South Island glaciers during the 1980s indicated there were about 3,155 glaciers with an area of at least . About a sixth of these glaciers covered more than 10 hectares. These include the Fox and Franz Josef glaciers on the West Coast, and the Haupapa / Tasman, Hooker, Mueller and Murchison glaciers in the east.