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


Multi-fault Quakes – It’s Complicated

EQC-funded research at the University of Canterbury is trying to pinpoint where faults might set each other off, creating a major multi-fault earthquake, and to estimate what the maximum magnitude could be.

Lead researcher Dr Tim Stahl says that the Kaikōura quake was the most complex multi-fault earthquake ever recorded, while other recent earthquakes have also involved more than one fault.

“Earthquakes that rupture across multiple faults don’t just affect a bigger area, they also add to the amount of energy released, creating stronger quakes,” says Dr Stahl.

“So it’s really important to understand more about multi-fault earthquakes,” he says.

Dr Stahl explains that if the 2016 Kaikōura quake had only ruptured the first fault, the Humps fault, it would have been a Mw 7 quake. But because it was the first of 20-odd other faults, it combined into a Mw 7.8 earthquake - which is around 16 times stronger.

“We really need to get a better idea of where this could happen and the impact it could create on the ground surface, on infrastructure like water and electricity, and on buildings,” he says.

EQC’s Chief Resilience and Research Officer Jo Horrocks says now that researchers can get detailed data on earthquakes through GeoNet, earthquakes rupturing across multiple faults almost seemed to be the “new normal”.

“Understanding more about how, when and where these types of multi-fault earthquakes might happen is critical for understanding natural hazard risk in New Zealand. Dr Stahl’s work bringing together the range of factors that lead to multi-fault earthquakes will be an extremely valuable contribution to understanding our earthquake risk and taking action to reduce the impact,” she says.

Dr Stahl says that while the Uniform California Earthquake Rupture Forecast is the current “gold standard” for understanding multi-fault earthquakes internationally, much more is needed for New Zealand conditions.

“When you’re looking at why and where an earthquake might jump across faults, you’re looking at factors like the distance between faults and whether a fault travels straight or on an angle. In New Zealand, however, we also want to be able to take into account how our rock types behave under seismic stress and what happens with faults that have been labelled ‘inactive’.”

Dr Stahl says that up until now, criteria for multi-fault earthquakes have been considered as black and white thresholds. His research is introducing “fuzzy logic” to put all the relevant factors together, giving a range of scenarios of what could happen.

“We want to be able to understand how all these factors might combine to make some rupture scenarios more likely than others. Ultimately the question we’re asking is “What is the maximum size earthquake we could have in a particular location?” says Dr Stahl.

Testing the computer modelling against real data is a critical part of the project.

“We have a huge amount of data from Kaikōura, Darfield and even Edgecumbe,” says Dr Stahl. “This gives us a great basis to test our modelling and make sure it is delivering good results for New Zealand conditions.

“Better models mean that we can give better information on the likelihood and impact of future multi-fault earthquakes to emergency managers, councils, infrastructure providers and the public.”

Dr Stahl says the project will focus on an area that has not had detailed investigation so far, between Waiau and Blenheim, where there are known faults that may rupture in future multi-fault earthquakes.

© Scoop Media

Business Headlines | Sci-Tech Headlines


Reserve Bank: Further Easing In Monetary Policy Delivered

Tēnā koutou katoa, welcome all. The Monetary Policy Committee agreed to expand the Large Scale Asset Purchase (LSAP) programme up to $100 billion so as to further lower retail interest rates in order to achieve its remit. The eligible assets remain ... More>>

Retail: Post-Lockdown Retail Card Spending Picks Up

The rise in retail card spending was boosted by sales of furniture, hardware, and appliances, Stats NZ said today. “For a third consecutive month, card spending on the long-lasting goods (durables) remained at higher levels than last year, after ... More>>

Contact: Business Drops, New Generation On Hold

New Zealand’s second-largest energy company Contact Energy (‘Contact’) released its full year financial results for the 12 months to 30 June 2020 (‘FY20’) this morning. More>>

Mining: OceanaGold Announces Receipt Of WKP Mining Permit

MELBOURNE, Australia, Aug. 6, 2020 /CNW/ - OceanaGold Corporation (TSX: OGC) (ASX: OGC) (the 'Company') is pleased to announce it has received the mining permit for Wharekirauponga ('WKP') on the North Island of New Zealand. ... More>>


Economy: COVID-19 Lockdown Has Widespread Effects On Labour Market

In the June 2020 quarter, the seasonally adjusted unemployment rate fell to 4.0 percent, down from 4.2 percent last quarter, while underutilisation rose, Stats NZ said today. More>>


NZ Post: New Research By NZ Post Shows Online Shopping Grew 105% In Alert Level 3

New research by NZ Post into how the COVID-19 response has impacted the way Kiwis shop online, shows online shopping increased 105%* when the country moved into Alert Level 3, and may have changed the way Kiwis shop permanently. Online spend peaked ... More>>


Antarctica NZ: Ice-Olation

Antarctica New Zealand is gearing up for a much reduced season on the ice this year and a very different deployment to normal! Before they head to one of the remotest places on the planet, all personnel flying south with the New Zealand programme will ... More>>


QV Valuations: July House Price Index Illustrates Market Resilience

According to the July 2020 QV House Price Index (HPI) results out today , property values recorded a marginal increase, up 0.2% over the month. This is somewhat of a turnaround from June, after the national index edged 0.2% lower. More>>


Property: Queenstown Rents Experience Biggest Drop In Seven Years

Rental prices in the Queenstown-Lakes district saw the biggest annual percentage drop in seven years after falling 28 per cent on June last year, according to the latest Trade Me Rental Price Index. Trade Me Property spokesperson Aaron Clancy said ... More>>

Seismology: The Quiet Earth

As many daily activities came to a halt during lockdown, the Earth itself became quiet, probably quieter than it has been since humans developed the technology to listen in. Seismologists have analysed datasets from more than 300 international ... More>>

RNZ: James Shaw Says Kiwibank, Not Ministers Should Decide On Investors

Climate Change Minister James Shaw says Kiwibank's decision to stop doing business with companies dealing in fossil fuels is the right one. More>>


FMA: Kiwis Confident Financial Markets Will Recover From COVID-19, Plan To Increase Investments

Despite the majority (60%) of investors experiencing losses as a result of COVID-19, the outlook on investing remains positive, according to a Financial Markets Authority (FMA) survey. Most Kiwis (71%) were optimistic that the pandemic will pass eventually ... More>>

FIRST Union: Warehouse Using Covid For Cover As Extensive Restructure Makes Everyone Worse Off

(FIRST Union comments on The Warehouse consultation and proposed restructure) 'Unfortunately the Warehouse have done the disappointing thing and used Covid-19 to justify a bunch of operational business decisions that will leave hundreds of workers without jobs ... More>>