2007 Gisborne earthquake

Tectonic setting

New Zealand lies along the boundary between the Indo-Australian plate and Pacific plate.

• 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, displacement is mainly taken up along the Kermadec-Tonga subduction zone, although the remaining dextral strike-slip component is accommodated by the North Island Fault System. Subduction off the coast takes place at the Hikurangi Trough, which runs parallel to the East Coast of the North Island and is the southern extension from the Kermadec Trench, however earthquakes here occur less frequently.

Earthquake

The earthquake occurred at 8:55 pm on 20 December 2007 off the coast of Gisborne, at a depth of about 40 kilometres. Shaking mostly affected Gisborne, but was felt throughout the country, from Auckland to Dunedin. Small appliances or furniture slipped or fell as far south as Wellington.

Effects

While the earthquake was initially reported to have caused no deaths, an elderly woman in Gisborne suffered a heart attack and died shortly after the quake. A number of buildings in central Gisborne were damaged and had their roofs cave in. The central business district was closed off to allow building inspectors to assess buildings for damage; three buildings had collapsed. Gisborne's standby sewage system was activated. There were power outages immediately after the earthquake hit. Temporary problems with phone, water and gas lines also occurred. The town clock stopped at 8:55 pm. The Earthquake Commission had received over 6,200 insurance claims costing a total of about $25 million, the biggest number since the 1987 Edgecumbe earthquake. It was earlier estimated that the cost of damage caused by the earthquake could rise to $30 million.

The National Crisis Management Centre was activated after the earthquake struck. A state of emergency started on 21 December and lasted until 22 December.

Liquefaction occurred near the Waipaoa River, and there was an increased activity in nearby mud volcanoes.

References

References

1. [https://www.geonet.org.nz/earthquake/story/2839343 M 6.7, Gisborne, 20 December 2007] {{Webarchive. link. (15 October 2018 . GeoNet.)
2. Mouslopoulou, V., Nicol, A., Little, T. A., & Walsh, J. J. (2007). [http://sp.lyellcollection.org/content/290/1/387.abstract Terminations of large strike-slip faults: an alternative model from New Zealand] {{Webarchive. link. (7 April 2022 . Geological Society, London, Special Publications, '''290''' (1), pp 387–415.)
3. link. (26 January 2020 , ''[[The New Zealand Herald]]'', 21 December 2007.)
4. (21 December 2007). "Quake 6.8 magnitude hits east coast". [[1News]].
5. (21 December 2007). "Woman's death blamed on NZ quake". ABC News.
6. [http://www.3news.co.nz/Rattled-Gisborne-residents-pick-up-the-pieces-after-quake/tabid/209/articleID/42241/cat/167/Default.aspx 'Rattled Gisborne residents pick up the pieces after quake'], 3News. 21 December 2007. Retrieved 6 June 2009. [https://web.archive.org/web/20120224195402/http://www.3news.co.nz/Rattled-Gisborne-residents-pick-up-the-pieces-after-quake/tabid/209/articleID/42241/cat/167/Default.aspx Archived] 10 June 2009.
7. "Earthquake Commission Annual Report 2007–2008".
8. [http://www.stuff.co.nz/4332985a11.html The $30m shockwave] {{Webarchive. link. (23 December 2007 , 22 December 2007)
9. (15 May 2008). "City was lucky, earthquake seminar told". NZPA.
10. (4 December 2008). "The Mw 6.6 Gisborne Earthquake of 2007: Preliminary Records and General Source Characterisation".