1855 Wairarapa earthquake
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| Date | 23 January 1855 |
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| Magnitude | 8.2–8.3 Mw |
| Depth | 33 km |
| Epicenter | 41°12′S 175°12′E / 41.20°S 175.20°ECoordinates: 41°12′S 175°12′E / 41.20°S 175.20°E |
| Areas affected | New Zealand, North Island |
| Casualties | 5–9 deaths |
The 1855 Wairarapa earthquake occurred on 23 January at about 9 p.m., affecting much of the Cook Strait area of New Zealand, including Marlborough in the South Island and Wellington and Wairarapa in the North Island. In Wellington, close to the epicenter, shaking lasted for at least 50 seconds. The moment magnitude is estimated to have been in the range 8.2–8.3, the most powerful recorded in New Zealand since systematic European colonisation began in 1840. This earthquake was associated with the largest observed movement on a strike-slip fault, maximum 18 metres (59 ft). It has been suggested that the surface rupture formed by this event helped influence Charles Lyell to link earthquakes with rapid movement on faults.
New Zealand lies along the boundary between the 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. In the North Island the displacement is mainly taken up along the Kermadec subduction zone, although the remaining dextral strike-slip component of the relative plate motion is accommodated by the North Island Fault System (NIFS). A group of dextral strike-slip structures, known as the Marlborough Fault System, transfer displacement between the mainly transform and convergent type plate boundaries in a complex zone at the northern end of the South Island. The earthquake occurred on the Wairarapa Fault which is part of the NIFS.
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