Jamie Morton is the NZ Herald's science reporter.

7.8 earthquake: How does it compare?

The elevation of Monday's quake from a magnitude 7.5 to 7.8 makes it compare in size only with four other New Zealand quakes in the past 150 years.

They are the 8.2 Wairarapa Earthquake in 1855, the Dusky Sound quake in 2009, the Napier Earthquake in 1931 and the Murchison Earthquake in 1929.

"GNS Science informed my office of the revised magnitude earlier today after reassessing the data from its stations across the country," Acting Civil Defence Minister Gerry Brownlee said.

"Because it took over a minute for the fault to rupture during this event, the standard method normally used to calculate the energy released during an earthquake was insufficient.

"The revised magnitude just tells us what anyone who felt the earthquake would already know - that it was a powerful tremor that lasted for a long time.

"It does not change what happened or how central government or local authorities responded.

It simply provides us with more knowledge about how significant this earthquake was.

Damage to infrastructure following earthquake near the Kaikoura coast. Photo / Supplied
Damage to infrastructure following earthquake near the Kaikoura coast. Photo / Supplied

"As expected with a larger earthquake, the revised magnitude does have an effect on the probabilities of forecast aftershocks, meaning it is now forecast that aftershocks may be larger in magnitude for a longer period of time.

"We know from the Christchurch earthquakes, the likelihood of earthquakes greater than magnitude 5 decreases over time."

The five largest quakes in the world since 1900 was the magnitude 9.4-9.6 quake that struck Valdivia, Chile on May 22, 1960; the 9.2 quake that struck Prince William Sound, Alaska, United States on March 27, 1964; the 9.1 to 9.3 Indian Ocean earthquake on December 26, 2004; the 9.0 Tohoku earthquake that hit Japan on March 11, 2011, 2011; and the 9.0 Kamchatka earthquakes in Russia on November 4, 1952.

Damage caused by the quake near Kaikoura. Photo / via Twitter
Damage caused by the quake near Kaikoura. Photo / via Twitter

New Zealand's biggest earthquakes

8.2 - Wairarapa, January 23, 1855
7.8 - North Canterbury, November 14, 2016
7.8 - Murchison, June 17, 1929
7.8 - Hawke's Bay, February 3, 1931
7.8 - Dusky Sound, July 15, 2009
7.6 - Pahiatua, March 5, 1934
7.5 - Marlborough, October 16, 1848
7.5 - Hawke's Bay, February 23, 1863
7.5 - Cape Farewell, October 19, 1868
7.3 - Hawke's Bay, February 13, 1931
7.3 - Auckland Islands, December 30, 2007
7.3 - North Canterbury, September 1, 1888
7.3 - Auckland Islands, December 30, 2007
7.2 - Puysegur Trench, south-west of Fiordland, November 23, 2004
7.2 - Wairarapa, June 24, 1942
7.1 - East Cape, September 2, 2016
7.1- Darfield, September 4, 2010
7.1 - Fiordland, August 22, 2003
7.1 - Arthurs Pass, March 9, 1929
7.1 - Inangahua, West Coast, May 24, 1968
7 - East Cape, February 6, 1995
7 - Wairarapa, August 2, 1942
6.9 - Nelson, February 12, 1893
6.8 - Gisborne, December 20, 2007
6.8 - Secretary Island, 10 August 1993
6.7 - George Sound, 16 October 2007
6.7 - Te Anau, 4 June 1988
6.6 - Grassmere, August 16, 2013
6.5 - Edgecumbe, March 2, 1987
6.5 - Cook Strait, July 21, 2013
6.4 - Porangahau, 13 May 1990
6.3 - Christchurch, February 22, 2011
6.2 - Eketahuna, 20 January 2014
6 - New Brighton, December 23, 2011
6 - Christchurch, June 13, 2011
Source: GNS Science

- NZ Herald

Get the news delivered straight to your inbox

Receive the day’s news, sport and entertainment in our daily email newsletter

SIGN UP NOW

© Copyright 2017, NZME. Publishing Limited

Assembled by: (static) on production bpcf03 at 27 May 2017 19:16:26 Processing Time: 618ms