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

 


Liquefaction Hazard Low in Taranaki

Liquefaction Hazard Low in Taranaki

Thu 23 May 2013

The possibility of earthquake-caused liquefaction in Taranaki is low, with just a few coastal areas potentially having the type of soil that might liquefy.

However those areas would need to be soil-tested before the potential for liquefaction can be confirmed or discounted.

A report by GNS Science has today (Thursday) been released by the region’s four councils, Powerco and Transpower.

In preparing the report, GNS Science examined existing land data held by South Taranaki, Stratford and New Plymouth district councils and Taranaki Regional Council as well as geological information held by GNS.

The key points in the report are:

• Taranaki’s geology is dominated by materials that are not liquefiable. Potential liquefaction hazards in Taranaki are limited to only a few sites.

• The potential for liquefaction hazards has been identified at Port Taranaki; and at the lower reaches of the Mohakatino, Rapanui, Tongaporutu, Mimi, Urenui, Onaero and Waitara rivers and their tributaries (in New Plymouth District); and the lower reaches of the Waitotara, Whenuakura and Patea rivers and their tributaries (in South Taranaki).

• The hazards are based on long time periods: Earthquakes strong enough to cause liquefaction damage to land (a Modified Mercalli Intensity of 8) are expected, on average, every 150 years at Port Taranaki and between 980 and 1070 years at the river areas.

• If liquefaction does occur, it is expected to be of low impact – nothing like what Christchurch experienced following the 2010 and 2011 quakes.

“This is not to say that a big earthquake would definitely cause liquefaction at these coastal sites,” says TRC Director – Environment Quality Gary Bedford.

“The report says these sites could have the potential to liquefy when the right conditions are present: Soil type, high water table and a very strong earthquake.

“The only way to know if a hazard does exist is to undertake direct soil testing at these sites.”

New Plymouth District Council will carry out more detailed investigations (cone penetrometer tests) at five river-mouth areas that have urban areas or residential buildings to confirm or discount the liquefaction potential. These areas are at Waitara, Onaero, Urenui, Tongaporutu and Mohakatino.

South Taranaki District Council Environmental Group Manager John McKenzie says STDC will add the GNS report to its hazard information that is used at times of development, such as when a building consent is applied for or when a land information memorandum is produced.

“The risk of liquefaction in South Taranaki is low and the areas identified are not subject to development pressure. However we will follow closely the results of the cone penetrometer tests,” says Mr McKenzie.

NPDC Manager Quality Assurance John Sutton says the study shows that if liquefaction ever did occur, it is likely the effect would be minor.

“This report was initiated as a result of Christchurch’s experience after the earthquakes in 2010 and 2011 and the enormous amount of liquefaction that resulted,” he says.

“The good news from this report is that if liquefaction ever occurs in Taranaki it probably wouldn’t be anywhere near Christchurch’s level of liquefaction, even with an earthquake that produces Modified Mercalli Intensity shaking of 8.”

The New Zealand MM – or Modified Mercalli – intensity scale grades the impact of an earthquake on people, which can be more useful as an indicator of the earthquake’s significance to the community than the absolute size of the earthquake itself. More information on the MM intensity scale is available on GeoNet’s website.


Documents

Fact sheet (One page 68KB PDF)

Liquefaction Hazard in the Taranaki Region report (34 pages 8.5MB PDF)


ENDS

© Scoop Media

 
 
 
 
 
Parliament Headlines | Politics Headlines | Regional Headlines

 

Two Years With New Methods: Crime Stats Show Increase Led By Burglary

The two years of data show an increase in the total victimisation rate of 3.1 per cent, with 12,060 more victimisations in the 2015/16 year when compared to 2014/15 year. From this increase, 72 per cent is attributable to burglaries. More>>

ALSO:

Auckland Relocation Grants: 12 Grants Paid So Far

Since the policy took effect one month ago, 12 applicants have received the non-recoverable grant, supporting 32 people. $54,508 has been paid out, covering things like moving costs, bond, rent in advance and letting fees. More>>

ALSO:

Vaccine Funding Change: HPV Vaccines For All Children

PHARMAC has today announced changes to funded vaccines, which will benefit an extra 100,000 people... The human papillomavirus (HPV) vaccine will be available for all children and adults up to the age of 26 years, and boys will now be included in the HPV school vaccination programme. More>>

ALSO:

Gordon Campbell: On Why The Opinion Polls For Key And Trump Defy Gravity

What is going on? Donald Trump got confirmed as the Republican presidential candidate at a bizarrely chaotic political convention… and promptly received an upwards bump in the polls to where he’s now rating ahead of Hillary Clinton, for only the second time this year. More>>

Sugar: Auckland Leisure Centres Axe Unhealthy Drinks

Auckland Council is to stop selling drinks that are sweetened by sugar from vending machines at its leisure centres in a bid to try to reduce obesity and type 2 diabetes... More>>

ALSO:

Gordon Campbell: On Todd McClay’s Faulty Memory

Time and again, whenever an issue arises the initial response by government is to deny or diminish the problem – nothing to worry about here, everything’s OK, move on. Then, hang on. In line with the usual pattern, as embarrassing details emerged into daylight, the story changed. More>>

ALSO:

Labour's 'Future Of Work': Major Reform Of Careers And Apprenticeships

The next Labour Government will transform careers advice in high schools to ensure every student has a personalised career plan, Leader of the Opposition Andrew Little says. More>>

ALSO:

State Investments Management: Treasury Likes IRD, Not Education Or Corrections

The Inland Revenue Department has scored an 'A' in the first tranche of the Treasury's investor confidence rating for state agencies that manage significant Crown investments and assets, gaining greater autonomy as a result, while the Corrections and Education ministries gained a 'C' rating. More>>

ALSO:

Govt Goal: NZ To Be "Predator Free" By 2050

Prime Minister John Key has today announced the Government has adopted the goal of New Zealand becoming Predator Free by 2050... “That’s why we have adopted this goal. Our ambition is that by 2050 every single part of New Zealand will be completely free of rats, stoats and possums." More>>

ALSO:

Get More From Scoop

 

LATEST HEADLINES

 
 
 
 
 
 
 
 
 
Regional
Search Scoop  
 
 
Powered by Vodafone
NZ independent news