1843 Wanganui earthquake

1843 Wanganui New Zealand

1843 Wanganui earthquake
Date	8 July 1843 (1843-07-08)
Magnitude	Mw 7+
Epicenter	near Wanganui, North Island
Countries or regions	New Zealand
Casualties	2 deaths

The 1843 Wanganui earthquake occurred on 8 July 1843 with an epicenter near Wanganui, North Island New Zealand. This was the first earthquake in New Zealand over magnitude 7 for which written records exist.^[1]

Tectonic setting

New Zealand lies along the boundary between the Australian and Pacific Plates. In 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 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).^[2] 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 South Island.^[3] The presumed epicenter of the 1843 earthquake is not, however, associated with any known fault.

Earthquake characteristics

Very little is known about the details of this earthquake except that it lasted for a few minutes.^[4] There is insufficient information to identify the epicenter or say anything about the type or amount of displacement involved.

Damage

Damage in the Wanganui area reached IX-X on the Mercalli intensity scale.^[5] Many houses were damaged, and a brick church at Pūtiki was destroyed.^[6] There was extensive lateral spreading of the terrace margin to the Whanganui River, and a section of Shakespeare Cliff fell into the river. Two people were killed when their house was swept away by one of the landslides caused by the earthquake.^[7]

See also

• 1848 Marlborough earthquake
• Earthquakes in New Zealand

References