New EQC funded research confirms major seismic events in West Otago
A press release from EQC on 24 March 2022 indicated that EQC-funded seismic research on the Nevis Fault in western Otago confirms that this low-seismicity area has the potential to create an earthquake similar in size to that of the 2010 Darfield Canterbury event.
“Professor Stirling, Postdoctoral Scholar Dr Jack Williams and a team of students and colleagues this week [24 March 2022] returned from digging two 25-metre long trenches high in the Upper Nevis Basin, south of Queenstown, to gain a better understanding of the Nevis Fault, and greater Nevis-Cardrona fault system”.
“The combined fault system stretches for about 100km from Lake Wanaka to near Garston in Southland, and has the potential to produce an earthquake well into the magnitude 7 range; with the new research finding evidence of at least two major prehistorical events”.
“We found evidence of the sediment layers being broken up, warped and thrust over each other, which would have been produced by significant seismic events,” says Professor Stirling.
Deep New Zealand sewer shaft completed
Ghella Abergeldie Joint Venture (GAJV) has completed the deepest open excavation shaft on Watercare’s Central Interceptor, New Zealand’s largest wastewater project.
The Central Interceptor team and its contractor GAJV have made progress on the $1.2bn(£630M) wastewater tunnel scheme in central Auckland.
The excavation crew has dug the 12.4m diameter May Road Shaft B to its final depth of 73.2m below ground level. The construction shaft to facilitate the main tunnel drive has been supported using secant bored piles, mesh, dowels and shotcrete at various depths.
According to the contractor, it reached the required depth on time and with no lost time injuries. “It is rare for engineers, geologists and operators to see how rock behaves at such depths. An achievement such as this can only be successfully undertaken with a strong team, great communication, and a positive attitude” GAJV said.
GAJV is delivering close to 20km of tunnels, 19 shafts, a pump station and wastewater management and network infrastructure works. The Central Interceptor tunnel will be 4.5m in diameter and run 14.7km from Grey Lynn under central Auckland and the Manukau harbour to Ma¯ngere.
From: Ground Engineering June 2022, digital edition https://www.geplus.co.uk/digital-edition/june-2022/