Local Govt | National News Video | Parliament Headlines | Politics Headlines | Search

 

New Research Shows Lower Threat From Wgtn Fault

Media Release
18 September 2009

New Research Shows Lower Threat From Wellington Fault


Click for big version

Shepherds Gully Fault (yellow), Ohariu Fault (green), Wellington Fault (red)



Click for big version


The major fault running through Wellington City is about 50 per cent less likely to rupture in the next 100 years than previously thought, according to research carried out under the ‘It’s Our Fault’ project.

Project Leader Russ Van Dissen, of GNS Science, points out that earthquakes will still occur in the Wellington region and the need to be prepared remains the same.

“There are about 50 active faults in the Wellington region and many of them are capable of producing a damaging earthquake,” Mr Van Dissen said.

Scientists have found that the Wellington Fault, regarded until recently as primed and capable of producing a big earthquake fairly soon, has longer quiet spells between big ruptures than was generally accepted.

‘It’s Our Fault’ is a seven-year, multi-agency project to improve the knowledge of the frequency, size and impacts of earthquakes in the Wellington region.



The $3.5 million project started in 2006 and is the most comprehensive study of earthquake risk in Wellington to date.

“For some years we have suspected that Wellington’s reputation for being ‘overdue for the big one’ was an exaggeration,” Mr Van Dissen said.

“Now that we have a more accurate picture of the hazard posed by the Wellington Fault, we expect this will assist civil defence planning and reduce uncertainty for those making business investment decisions.”

The Wellington Fault extends between Wellington and the Bay of Plenty. However, the study focused on the 80km-long segment closest to the Capital. It starts in Cook Strait and extends through Karori and Wellington City and along the Hutt Valley into the Tararua Mountain Range.

Until recently, available evidence suggested that this southern segment ruptured at intervals of about 600 years and last ruptured about 450 years ago, producing an earthquake of at least magnitude 7.

The new findings show it ruptures about every 900 years and last ruptured about 300 years ago.

“We are delighted to have made solid progress in understanding the Wellington Fault and its threat to the Wellington region,” Mr Van Dissen said.

The findings come from detailed geological investigations to better characterise the earthquake activity of the faults in the Wellington region. The project also incorporated the accurate mapping of Cook Strait faults by the National Institute of Water and Atmospheric Research (NIWA).

Scientists have also used Global Positioning System (GPS) studies to better understand the movement of the tectonic plates under Wellington, as well as computer modelling of the complex relationships among the many faults in the lower North Island.

The work has been a collaborative effort involving GNS Science, NIWA, Victoria University of Wellington, and the University of Canterbury.

Mr Van Dissen said a reduced likelihood of the Wellington Fault rupturing in the near future did not mean that damaging earthquakes were no longer a threat to Wellington.

Moderate-sized local earthquakes – magnitude 6.0 to 6.9 – or larger distant earthquakes, now have more relevance in terms of planning and preparedness in Wellington.

“Strong ground-shaking from these categories of earthquakes could be expected to occur several times in an average person’s lifetime.”

Earthquakes of moderate magnitude generally cause damage over a smaller area. The resultant impact on communities and infrastructure would be less than a rupture of the Wellington Fault, which is expected to produce an earthquake of about magnitude 7.5.

“However, smaller magnitude earthquakes are more frequent than large ones,” Mr Van Dissen said.

The new knowledge and understanding being built through this project will enable more accurate hazard and risk estimates for the Wellington region. This will benefit a wide range of industries and agencies, help boost community resilience, and facilitate quick recovery from a damaging earthquake if proper preparation is in place.

To date the ‘It’s Our Fault’ project is supported by the Earthquake Commission, Wellington City Council, the Accident Compensation Corporation, and the Foundation for Research Science and Technology. Greater Wellington Regional Council has recently committed to support the project.

Its Our Fault (pdf)

Note: The Richter or Local magnitude scale for earthquakes assigns a number to quantify the amount of energy released by an earthquake. It is a logarithmic scale meaning an increase of a whole unit – magnitude 6.0 to magnitude 7.0 – represents 30 times more energy produced. An increase of two units – magnitude 5.0 to magnitude 7.0 – represents 900 times more energy. The energy released by an earthquake closely relates to its destructive power.

ENDS

© Scoop Media

 
 
 
Parliament Headlines | Politics Headlines | Regional Headlines

Mosque Shooting Response: Ban On Military Style Semi-Automatics And Assault Rifles

Military style semi-automatics and assault rifles will be banned in New Zealand under stronger new gun laws announced today, Prime Minister Jacinda Ardern says... Related parts used to convert these guns into MSSAs are also being banned, along with all high-capacity magazines.

“An amnesty will be put in place for weapons to be handed in, and Cabinet has directed officials to develop a buyback scheme...All semi-automatic weapons used during the terrorist attack on Friday 15 March will be banned." More>>

RNZ Report: No Mention Of Right-Wing Threat In 10 Years Of GCSB/SIS Docs
There is not one specific mention of the threat posed by white supremacists or right-wing nationalism in 10 years of public documents from the Security Intelligence Service or the GCSB. More>>

Two Minute Silence Friday: Auckland Mosques Opening Their Doors To All
Mosques in the four corners of Auckland will open their doors on Friday night for people of all faiths to gather in remembrance of the 50 lives lost in the Christchurch shootings. More>>

SCOOP COVERAGE: CHRISTCHURCH MOSQUES TERROR ATTACK
For the Latest: Scoop Search - Christchurch
 

Gordon Campbell: On The School Climate Strike

Locally, the school strike has won a ton of support for bringing climate change to the fore. Yet the strikers don't want mere expressions of support. They want action. More>>

ALSO:

"Grabbed And Struck In The Face": Greens Co-Leader Attacked While Walking To Work

Green Party co-leader James Shaw was the victim of an unprovoked attack when he was walking to work in Wellington. More>>

ALSO:

████████ ████ ███: Latest OIA Statistics Released

The latest statistics cover 110 agencies that collectively completed 18,106 official information requests between July and December 2018, a 16.4% increase on the 15,551 requests for the previous six months. More>>

ALSO:

'Hit And Run' Inquiry: New Legal Action Over Secrecy

The lawyer representing the Afghan villagers in the inquiry into Operation Burnham has launched legal proceedings calling for a judicial review in the investigation. More>>

ALSO:

From Hydro Plan To...: Mokihinui River Land To Join Kahurangi National Park

A total of 64,400 hectares of conservation land in the Mokihinui River catchment on the West Coast north of Westport, including 15 km of riverbed, is being added to Kahurangi National Park. “Adding this area, roughly half the size of Auckland City, to Kahurangi is the largest addition of land to an existing national park in New Zealand’s history,” Eugenie Sage said. More>>

ALSO:

 
 
 
 
 

LATEST HEADLINES

  • PARLIAMENT
  • POLITICS
  • REGIONAL
 
 

InfoPages News Channels