Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 


Deep Alpine Fault sensitive to nearby earthquakes

MEDIA RELEASE

25 August 2014

___________________________________________________________

Deep Alpine Fault sensitive to nearby earthquakes

Victoria University of Wellington researchers have discovered that seismic waves produced by earthquakes happening several hundred kilometres away trigger activity deep beneath the Alpine Fault.

Using a network of seismic recorders called the Southern Alps Microearthquake Borehole Array (SAMBA), set up during a 2009 study, PhD student Calum Chamberlain is exploring the range of seismicity occurring in the central section of the Alpine Fault.

Calum is researching under the supervision of Associate Professor John Townend and Professor Tim Stern from the School of Geography, Environment and Earth Sciences and in collaboration with Dr David Shelly of the United States Geological Survey. This work was recently published online by the journalGeochemistry, Geophysics, Geosystems (G-Cubed).

The Alpine Fault runs along the western side of the Southern Alps and forms the boundary between the Pacific tectonic plate (to the east) and the Australian plate (to the west). Calum’s PhD research involves regular helicopter trips into the Southern Alps to download data and make sure the seismic recorders are operating reliably.

“The Alpine Fault is known from geological measurements to produce large earthquakes every few hundred years, most recently in 1717 AD, but this research is focussed on much, much smaller earthquakes happening almost every day. We are investigating how the fault is being loaded towards an eventual large earthquake,” says Dr Townend.

“Our group has recently detected very small earthquakes—smaller than magnitude one—occurring at depths of 15 to 40 km near the Alpine Fault. These earthquakes have distinctive low-frequency characteristics that enable them to be detected and monitored despite their small size, and provide one of the few signs we have of present-day faulting activity deep inside the plate boundary.”

Analysing three years of data, Calum has found that low-frequency earthquakes happen almost continuously near the Alpine Fault southwest of Aoraki Mt Cook. In addition, when a large earthquake happens elsewhere in the South Island, such as the Dusky Sound earthquake of 2009 in Fiordland or the 2010 and 2011 Canterbury sequence of earthquakes, there’s a sharp spike in the production of low-frequency earthquakes.

One example is the magnitude 6 earthquake near Christchurch in June 2011 that triggered many low-frequency earthquakes on the Alpine Fault over the course of several days. “The Alpine Fault responds to earthquakes hundreds of kilometres away, showing that it’s very sensitive to the small stresses associated with seismic waves,” says Calum.

The next stage of Calum’s study is focussed on understanding the conditions beneath the fault that make it extremely sensitive to weak triggers. This work will also add to knowledge of the fault’s structure at depth.

“Documenting how often these low-frequency earthquakes occur and how they’re triggered by very small perturbations in stress is important for determining how the Alpine Fault is loaded by tectonic processes and better understanding the hazard it poses,” says Dr Townend.

The research is funded by the Marsden Fund of the Royal Society of New Zealand and Victoria University of Wellington, and viewable online athttp://doi.wiley.com/10.1002/2014GC005436


© Scoop Media

 
 
 
 
 
Business Headlines | Sci-Tech Headlines

 

Future Brighter Money: RBNZ Releases New Bank Note Designs

New Zealand’s banknotes are getting brighter and better, with the Reserve Bank today unveiling more vibrant and secure banknote designs which will progressively enter circulation later next year. More>>

ALSO:

Commerce: Supermarket Inquiry Finds No Breaches By Countdown

The Commerce Commission inquiry into anti-competitive behaviour by Countdown supermarkets, alleged by former Labour Party MP Shane Jones, has found nothing to warrant prosecution, although it warns supermarkets to take care in the way they communicate... More>>

ALSO:

Crown Accounts: English Flags ‘Challenge’ To Budget Surplus

Finance Minister Bill English is warning next month’s half yearly fiscal and economic update from the Treasury may not forecast a budget surplus, saying that returning the government’s accounts to surplus in 2015 will be “a challenge”, given the decline in commodity prices and weak global inflation. More>>

ALSO:

March 2015: Netflix To Launch In Australia And New Zealand

World’s Leading Internet Television Network to Offer Original Series, Movies, Documentaries, Stand-Up Comedy Specials and TV Shows for Low Monthly Price More>>

ALSO:

Price Of Cheese (Is Up): Dairy Product Prices Fall To Five-Year Low

Dairy product prices fell in the latest GlobalDairyTrade auction to the lowest level in more than five years, led by declines in rennet casein and skim milk powder. More>>

ALSO:

Gordon Campbell: On The Australians Scoring Trade Points Against Us With The Chinese

It hasn’t been a great year for Trade Minister Tim Groser... To top it off, Australia has just signed a FTA with China that has far better provisions on dairy exports than what New Zealand currently enjoys in our own FTA with China. More>>

ALSO:

Iwi & Local Consultation: Oil And Gas Block Offer 2015 Begins

Energy and Resources Minister Simon Bridges today announced the start of the Block Offer 2015 process for awarding oil and gas exploration permits. More>>

Industrial Action: Stats NZ Throwing Public Money Away Duplicating Data

The Public Service Association (PSA) says Statistics NZ are throwing money away by collecting the same data twice for official statistics such as the Consumer Price Index... As part of the ongoing industrial action, field interviewers who are PSA members are continuing to collect data, but are not sending it through to Statistics NZ. More>>

ALSO:

Other Stats:

Space: Rosetta's 'Philae' Makes Historic First Landing On A Comet

After more than a decade traveling through space, a robotic lander built by the European Space Agency has made the first-ever soft landing of a spacecraft on a comet. More>>

ALSO:

Get More From Scoop

 
 
Standards New Zealand

Standards New Zealand
 
 
 
 
 
 
 
 
Sci-Tech
Search Scoop  
 
 
Powered by Vodafone
NZ independent news