Earthquakes in New Zealand

Major active fault zones of New Zealand showing variation in displacement vector of Pacific Plate relative to Australian Plate along the boundary
Distribution of earthquakes (magnitude 5 or greater)

Earthquakes in New Zealand are due to the country being part of the Pacific Ring of Fire, which is geologically active. About 20,000 earthquakes, most of them minor, are recorded each year.[1] About 200 of these are strong enough to be felt.[2] As a result, New Zealand has very stringent building regulations.

Distribution

Most earthquakes in New Zealand occur along the main ranges running from Fiordland in the southwest to East Cape in the northeast. This axis follows the boundary between the Indo-Australian and Pacific plates. Large earthquakes are less common along the central Alpine Fault, where the plates are not subducting and the forces are accommodated in different ways.

The largest city within this high-risk zone is the nation's capital, Wellington, followed by Hastings then Napier. All these cities have experienced severe earthquakes since European settlement.

Societal effects

Quite early on, European settlers were faced with the reality of earthquakes in their new home. On 26 May 1840, the new settlement at Port Nicholson was struck by the first of a number of earthquakes and tremors.[3] Today earthquakes are a common part of New Zealand society and people have become well equipped to deal with them. Each year sees at least one Magnitude 6.0 earthquake or above.

Public education

The New Zealand Earthquake Commission (EQC) provides public education to much of the country. As outlined in its statement of intent, it hopes to provide "public education about seismic hazards and methods of reducing or preventing seismic disaster damage." The EQC sponsors exhibitions on seismic hazards in the Te Papa Museum of New Zealand, and is responsible for social marketing campaigns.[4] An extensive advertising campaign by the EQC across New Zealand's main television networks ran from June 2005 to June 2006. The adverts outlined the risks earthquakes pose to New Zealand and measures households can take to "Quake Safe their house." The slogan used throughout EQC Quake Safe campaigns is "Fix. Fasten. Forget."[5] Additionally, in October 2006, many households received free "EQ-IQ" fridge magnets from the EQC.[6]

Building regulations

Early settlers learned fairly quickly the importance of using appropriate building methods in an earthquake-prone country. The 1848 earthquake, centred in Marlborough, caused great damage to the brick and masonry buildings in Wellington, and the city was rebuilt mainly in wood; consequently it suffered comparatively little damage in the 8.2 magnitude earthquake of 1855, which lifted the land 2–3m. After the 1931 Hawke's Bay earthquake, many buildings in Hastings and Napier were damaged. New building regulations meant that any new buildings constructed afterwards attempted to take earthquake shaking into account in building design.[7]

Notable earthquakes

Date Location Region Magnitude (ML) Magnitude (Mw) Depth Latitude Longitude Fatalities Further information
8 July 1843 Near Wanganui Manawatu 7.6 7.5 12 km 39.59°S 176.20°E 2 1843 Wanganui earthquake
16 Oct 1848 Blenheim Marlborough 7.4 7.8 12 km 41.89°S 173.60°E 3 1848 Marlborough earthquake
23 Jan 1855 Lake Wairarapa Wairarapa 8.2 8.2 33 km 41.198°S 175.20°E 9 1855 Wairarapa earthquake[8][9][10][11]
23 Feb 1863 Waipawa Hawke's Bay 7.5 39.57°S176.34°E 1863 Hawke's Bay earthquake[12]
5 Jun 1869 Christchurch Canterbury 5.7 1869 Christchurch earthquake
1 Sep 1888 Lewis Pass North Canterbury 7.0 7.1 12 km 42.59°S 172.55°E 1888 North Canterbury earthquake
16 Nov 1901 Cheviot North Canterbury 6.8 12 km 42.74°S173.35°E 1 1901 Cheviot earthquake
9 Mar 1929 Arthur's Pass Canterbury 7.0 12 km 42.83°S 171.83°E 1929 Arthur's Pass earthquake
17 Jun 1929 Murchison West Coast 7.3 7.8 20 km 41.69°S 172.20°E 17 1929 Murchison earthquake
3 Feb 1931 North of Napier Hawke's Bay 7.4 7.8 20 km 39.29°S177.00°E 256 1931 Hawke's Bay earthquake
5 Mar 1934 Pahiatua Manawatu 7.2 12 km 40.54°S176.29°E 2 1934 Pahiatua earthquake
24 Jun 1942 Masterton Wairarapa 6.5 12 km 40.95°S175.68°E June 1942 Wairarapa earthquake
1 Aug 1942 Masterton Wairarapa 6.8 40 km 41.01°S175.51°E 1 August 1942 Wairarapa earthquake
24 May 1968 Inangahua Junction West Coast 6.7 7.1 12 km 41.75°S 172.04°E 2 1968 Inangahua earthquake
5 Jan 1973 Taupo Waikato 7.0 7.0 163 km 39.03°S 175.26°E 1973 Taupo earthquake
2 Mar 1987 Edgecumbe Bay of Plenty 6.1 6.5 10 km 37.88°S176.80°E 1987 Edgecumbe earthquake
20 Dec 2007 Gisborne East Cape 6.7 6.6 44 km 38.89°S 178.44°E 1 2007 Gisborne earthquake
25 Aug 2008 Hastings Hawke's Bay 5.9 6.0 32 km 39.72°S 176.85°E 2008 Hastings earthquake
15 Jul 2009 Dusky Sound Southland 7.8 12 km 45.76°S 166.58°E 2009 Fiordland earthquake
4 Sep 2010 Darfield Canterbury 7.1[13] 7.2 10 km 43.52°S172.16°E 2010 Canterbury earthquake
22 Feb 2011 Christchurch Canterbury 6.3 6.2 5.9 km 43.58°S 172.67E 185[14] 2011 Christchurch earthquake
13 Jun 2011 Christchurch Canterbury 6.4 6.0 6.9 km 43.56°S 172.73°E 1 June 2011 Christchurch earthquake
3 Jul 2012 South Taranaki Bight Taranaki 7.1 6.3 229 km 40.00°S173.75°E 2012 Opunake earthquake
21 Jul 2013 Cook Strait Wellington Marlborough 6.5 6.5 17 km 41.61°S 174.33°E 2013 Seddon earthquake
16 Aug 2013 Lake Grassmere Marlborough 6.6 6.5 8 km 41.73°S 174.15°E 2013 Lake Grassmere earthquake
20 Jan 2014 Eketahuna Wairarapa 6.2 - 33 km 40.62°S 175.85°E 2014 Eketahuna earthquake [15]

See also

Notes

  1. ↑ Radio NZ news report on 2007 Gisborne earthquake
  2. ↑ Earthquakes: The Short Story, Te Ara Encyclopedia of New Zealand
  3. ↑ Dench 2005, p. 57.
  4. ↑ EQC Statement of Intent EQC Statement of Intent
  5. ↑ "EQC Annual Report 2006-2007"EQC Annual Report 2006-2007
  6. ↑ "EQC Annual Report 2005-2012" EQC Annual Report 2005-2006
  7. ↑ McSaveney, Eileen 'Earthquakes', Te Ara - the Encyclopedia of New Zealand, updated 21-Sep-2007
  8. ↑ GeoNet. "M 8.2, Wairarapa, January 23, 1855". Retrieved 26 December 2011.
  9. ↑ McSaveney, M.J., Graham, I.J., Begg, J.G., Beu, A.G., Hull, A.G., Kyeong, K. & Zondervan, A. 2006. Late Holocene uplift of beach ridges at Turakirae Head, south Wellington coast, New Zealand. New Zealand Journal of Geology and Geophysics abstracts, 49, 337-358.
  10. ↑ Rodgers, D.W.; Little T.A. (2006). "World's largest coseismic strike-slip offset: The 1855 rupture of the Wairarapa Fault, New Zealand, and implications for displacement/length scaling of continental earthquakes". Journal of Geophysical Research 111 (B12408). Bibcode:2006JGRB..11112408R. doi:10.1029/2005JB004065.
  11. ↑ McSaveney, Eileen (2 Mar 2009). "Story: Historic earthquakes Page 3 – The 1855 Wairarapa earthquake". Te Ara - the Encyclopedia of New Zealand. Retrieved 26 December 2011.
  12. ↑ http://www.gns.cri.nz/Home/Learning/Science-Topics/Earthquakes/New-Zealand-Earthquakes/Where-were-NZs-largest-earthquakes
  13. ↑ "New Zealand earthquake report - Sep 4 2010 at 4:35 am (NZST)". GeoNet. 4 September 2010. Retrieved 4 September 2010.
  14. ↑ "List of deceased - Christchurch earthquake". New Zealand Police. 3 May 2011. Retrieved 31 May 2011.
  15. ↑ "New Zealand Earthquake Report Magnitude 6.2, Monday, January 20, 2014 at 3:52:45 pm (NZDT)". GeoNet. 21 January 2014. Retrieved 21 January 2014.

References

External links

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