How New Zealands improved earthquake resilience helped withstand Wellington quake

Following the country's most destructive cyclone in decades, New Zealand's North Island was hit by a 6.1-magnitude offshore earthquake yesterday, but the infrastructure and resilience systems are in place to deal with it more effectively than they were a few years ago, according to a former resident and chartered geologist. The improvement in New Zealand's reaction to severe weather events after the magnitude-6.3 Christchurch earthquake in 2011 and the magnitude-7.8 Kaikura earthquake in 2016 is demonstrated. In 2011, following the major Christchurch earthquake, Jamie Codd, Aecom's assistant director for ground engineering, relocated to New Zealand. The closest major city to this week's earthquake, Wellington, he claimed, has previously been in a very precarious situation. In Wellington is significantly different from Christchurch; it has a larger population and is a little bit more remote physically," he added. Since there were few entrances, there was a chance that it would become isolated in a strong earthquake. The Waka Kotahi NZ Transport Agency has spent money to make the roadways more resilient and to provide access for people, resources, and commodities into and out of the city in order to counteract this. The Transmission Gully Motorway, a new 27-km route that extends past Wellington with the express goal of increasing safety and providing greater access, has been built as a result of this. The NZ$1.25 billion (£650 million) road's construction began in 2014 and was finished in 2022. The plan for using this access is also an element of the strategy.of developing toughness. "I'm certain that the local authorities on the Kapiti Coast, where this earthquake occurred, will implement resilience strategies," Codd said. They react to them since they are aware of which roadways and critical infrastructure would be impacted. The machinery and plants required for repair activities will have routes planned to get to their destinations.

Meanwhile, State Highway 1, the nation's longest and busiest road, was a crucial piece of infrastructure that was harmed in the 2016 Kaikura earthquake. Numerous rockfalls, more than 750,000 m3 of debris from 85 landslides, and substantial damage were all sustained by the transit route north and south of Kaikura. Since then, a specific section of the road beneath a steep 90-meter-high cliff face has continued to endure perilous rock falls that might harm the road or even worse. The optimum mitigation for the situation was determined to be the possibility of a self-cleaning rockfall canopy. The 104-meter-long one that was created and put in place for this area after careful rock fall modelling is the first of its kind in the southern Hemisphere. It is "self-cleaning" because the building's elasticity is sufficient to utilise the kinetic energy of the falling boulders to deflect them into a safe area- off the road. In June 2021, the canopy was completed. When it comes to the structures, Codd noted that "after the Christchurch earthquake, there was a lot of debate about construction rules and how vital they are." He said, "There was a time where teams were inspecting which buildings conformed and which didn't in Christchurch, Wellington, and presumably Auckland as well. Some structures were flagged as needing renovation and not conforming. Since it occurred in 2012 and 2013, there was plenty of time to update those structures and introduce new technology.

Base isolators, often referred to as a base isolation system, are a technique that was developed by New Zealand scientist Dr. William Robinson in the 1970s to lessen the effects of earthquakes on structures. The building's weight is supported by the base isolation, which also distributes seismic pressures and enables the foundations to move horizontally and independently of the superstructure. Base isolation may be achieved using a variety of methods, most often employing rubber bearings, friction bearings, ball bearings, and spring systems. Base isolation has been used in the construction of several significant structures in New Zealand. The Wellington William Clayton Building, Wellington's Te Papa Museum, Parliament House,Christchurch Women's Hospital. Te Papa's base isolation system consists of 152 flexible bearings that lie between the main structure and the concrete slab of its foundation. These bearings are defined as a "rubber-and-steel sandwich with a core of lead." When there is an earthquake, it will move apart from the structure and absorb most of the shock, while the main Te Papa "rolls with the punches" and experiences a slower, longer motion. For this movement, there is a 400-mm seismic gap; during the 2016 earthquake, it "slid" around 15-20 mm.

Although New Zealand is well-equipped to handle earthquakes, it is constantly enhancing its preparedness. The most recent earthquake will reveal the nation's level of preparedness for the next major one and areas for improvement. This is particularly significant since the South Island of New Zealand is situated immediately on top of the 800-km Alpine Fault, which separates the Australian and Pacific tectonic plates. On the Alpine Fault, a significant earthquake has occurred every 300 years or so for the past 8,000 years. The last one, known as the Alpine Fault of magnitude 8 (AF8), happened in 1717; the next one is expected to happen within the next 50 years. Although Codd admits that "humans have short memory,"claims that the government of New Zealand works to maintain inhabitants' awareness of the need for earthquake resilience through the Toka T Ake Earthquake Commission, GNS Science, and the institute of geological and nuclear sciences. They do an excellent job of keeping it on people's minds and ensuring that they are prepared to act when necessary. He stated, "I believe it may be one of the lessons they've learnt from Christchurch.

Mining and civil engineering company Seequent, with headquarters in New Zealand, has also researched how the Christchurch earthquake changed New Zealand's seismic resistance. Prior to 2011, residents were not generally aware of the natural phenomenon of liquefaction, in which sands or silts that are saturated with water almost turn into liquid when shaken, according to Seequent Geotechnical Analysis Content Development Manager Dennis Waterman. However, residents are now frequently faced with it. Because of the way they were formed, the Canterbury Plains in particular contain a lot of liquefiable sands, which should be taken into consideration for any construction projects, according to Waterman. "For example, one may envision keeping the regions that are more liquefiable for sports fields or parks instead of residential areas and developing new residential areas on these less delicate parts This is a thought that was never previously entertained.

The reclaimed area between Lambton Quay and the shoreline is really also made of loose material and is thus liquefiable, he explained, adding that the Christchurch earthquakes "raised a lot of awareness." In reality, a similar earthquake closer to Wellington will definitely produce that again, but on a greater scale, as the 2016 Kaikoura earthquake had significantly liquefied the land around Wellington Port. Nevertheless, it is difficult to stop liquefaction from happening or to construct buildings that won't be significantly impacted by it. The lesson from Christchurch of trying to avoid development on liquefiable soils cannot be applied to the existing parts of Wellington longer, And the next step is to use measures to reduce the danger and harm of an earthquake in Wellington. That is not to say that it is a simple answer; inside a city, such measures are expensive and challenging to use. It demonstrates that there may be a big gap between understanding a lesson and being able to implement it. We must immediately find a solution since we are aware that Wellington may have an issue.