1968 Inangahua earthquake
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| Date | 24 May 1968 |
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| Origin time | 5:24 am NZDT (UTC+13) |
| Magnitude | 7.1 Mw |
| Depth | 12 km (7.5 mi) |
| Epicenter | 41°46′S 172°02′E / 41.76°S 172.04°ECoordinates: 41°46′S 172°02′E / 41.76°S 172.04°E |
| Areas affected | New Zealand |
| Max. intensity | X (Very Destructive) |
| Peak acceleration | ~0.6 g |
| Casualties | 3 dead, 14 injured |
The 1968 Inangahua earthquake struck 25 kilometres (16 mi) west of Murchison, New Zealand, near the small town of Inangahua Junction at 5:24 am NZDT on 24 May 1968. The earthquake had a moment magnitude of 7.1, a local magnitude of 6.7, a surface wave magnitude of 7.4 and a maximum Mercalli intensity of X (Very Destructive). It occurred at a depth of only 12 kilometres (7.5 mi), being extremely shallow for an earthquake of its size. It resulted in the deaths of three people, with a further 14 people injured, making it the fifth deadliest earthquake in New Zealand's recorded history. Numerous aftershocks followed the quake, including 15 that were magnitude 5 or greater and occurred within a month.
New Zealand lies along the boundary between the Indo-Australian and Pacific Plates. In the South Island most of the relative displacement between these plates is taken up along a single dextral (right lateral) strike-slip fault with a major reverse component, the Alpine Fault. The 1968 Inangahua earthquake occurred along the Northern section of the Alpine Fault, and was considered quite average for what the fault can produce.
The earthquake ruined many years of expensive work improving State Highway 6 in the Inangahua and Buller Gorge areas. In a section of 50 kilometres (31 mi), the road through Buller Gorge was blocked in more than 50 places, either buried under landslides or where the road itself had collapsed into the gorge. The earthquake also damaged or destroyed more than 50 bridges. It also derailed two goods trains, and over 100 kilometres (62 mi) of damaged railway track had to be replaced.
All roads in and out of Inangahua were blocked by landslides. The electricity and phone networks were out, and many water pipes in Inangahua were damaged beyond repair.
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