The 2020 New Zealand Earthquake (pronounced "TWENTY-TWENTY", also known as the Alpine Fault Quake and the 2020 South Island Quake) is a magnitude 8.7 earthquake that will occur on the Alpine Fault in New Zealand's South Island at 11:31 (local) on Thursday, June 18th, 2020. It will be centred roughly 60km west of Queenstown, in the South Westland area.
The earthquake is the first major earthquake of the 2020s decade, and will be the worst quake (both in casualties and devastation) in New Zealand's history. In terms of total death toll, it will be the worst earthquake since the 2015 Nepal Earthquake and the worst earthquake to occur in a Western nation since the 2011 Christchurch Earthquake, also in New Zealand. It will also become the world's most widely-felt earthquake, being felt more than 2100km away in Sydney, Australia. The earthquake will trigger a horizontal earth shift of between 6 to 8 metres, and a vertical shift of 4 metres.
Over the last thousand years, there have been four major ruptures along the Alpine Fault causing earthquakes of about magnitude 8. Average slip rates in the fault's central region are about 30mm a year, very fast by global standards.
By the early 21st century, information about the risks associated with the Alpine Fault is common-place. A poll that will be conducted in 2017 stated that 74% of New Zealanders view the rupture of the Alpine Fault as the "greatest potential disaster ever for New Zealand". Despite this, however, very little preparation will have been made by 2020, despite repeated warnings that began well over a decade earlier.
At 11:31am (local time) on Thursday, June 18th, 2020, the Alpine Fault will rupture along 350km of the fault, from south-west South Westland to an area of dense forest 100km south of Westport. Violent shaking will occur in Queenstown, where severe structural damage or complete destruction will occur. Shaking ranging from violent to strong will also be felt in Wanaka, where damage will occur, and moderate to strong shaking will also be recorded in Dunedin, which experiences minor damage. The earthquake will be felt along the east Australian coastline, including in cities such as Sydney.
A powerful tsunami on New Zealand's west coast will devastate both the South and North Islands of New Zealand, and damage will occur as far north as New Plymouth and as far south as Stuart Island. The death toll from the tsunami will be over 3,000.
The shaking will be felt all over the South Island, as far as Nelson in the north and Invercargill in the south, which will also face moderate or minor damage. Many bridges and roads will be damaged or completely destroyed, and tsunamis up to 30m high will occur in Milford Sound, where over 500 people will die when tour boats, loaded with passengers from the United States and France, will be destroyed. Westport's road links will be severely damaged and the town will remain cut off after the earthquake for five days.
The final death toll will stand at 9,305 (including subsequent tsunami) of which over 6000 of these casualties will occur in Queenstown, where many foreign nationals and tourists will be holidaying during the winter ski season. 9 hotels will completely collapse during the earthquake, and a further 20 will be severely damaged. The remaining casualties will occur in Wanaka, which recorded around 300 deaths. International aid will flow into New Zealand in the weeks following the quake.
Aftershocks will continue for years, including a magnitude 7.0 earthquake that will strike just two weeks after the initial quake, killing a further 14 people.