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The aim of this paper is to report on fatal landslides resulting from two extraordinary storm events in January and February 2023, in Auckland, New Zealand, including the characteristics of the terrain, the site geology, and the storms. The January 27 Auckland Anniversary storm was from an "atmospheric river," dumping Summer's worth of rain (265 mm) in one day. This was the highest 24-h total on record, estimated a 1 in 200-year event, with a peak 2-min rainfall of 4.2 mm, coinciding with Friday's evening "rush hour." This led to widespread landsliding throughout Auckland, including a fatal landslide in Parnell, central Auckland. Notably, this occurred only meters from a similarly destructive landslide in 1997. With January 2023 Auckland's wettest January on record, and with the region still in a state of emergency, Tropical Cyclone Gabrielle crossed the region on February 13–14. This also caused widespread landsliding, including a fatal landslide at Muriwai on the west Auckland coast. Fatal landslides from the same escarpment had occurred in 1965, close to the February 13, 2023, fatal landslide. Taken together, both storm events caused > 140,000 landslides across the North Island, and flooding, making hundreds of people homeless, with damage estimates of > US$8.6 billion (3.4% of NZ's GDP). For future disaster risk reduction, attention should be paid to revising legislation and local planning, which currently allows people to legally build (and re-build) houses in landslide-prone areas of New Zealand. [ABSTRACT FROM AUTHOR]

A brief investigation of an ongoing urban landslide complex in Auckland, New Zealand, is presented. After progressive deformation of a carpark surface in the centre of Birkenhead over several months, two landslides occurred, in October and November 2017. The landslides occurred adjacent to each other at the head of the Rawene Reserve area, with rotational slumping forming headscarps and each landslide developing an earthflow component with a runout over 100 m. The failures appear to be formed of fill and residual soil. While the residual soil is formed on Miocene East Coast Bays Formation sands and silts, historical aerial images reveal that the fill was emplaced on the slopes in the 1970s and 1980s within gullies, to allow the carpark to be built. The precise triggering mechanism of the landslide activity is unknown. Although rainfall-triggered landslides occurred over much of the Auckland region in early 2017 due to the passing of ex-tropical cyclone Debbie, total rainfall for 2017 in the area (1299 mm) closely mirrored the 1980-2010 ‘normal’ of 1231 mm. Anecdotal evidence from eyewitnesses in days leading up to the first landslide highlighted resident’s concerns about the effects of vibration from piling operations at a construction site adjacent to the carpark, where cracking and subsidence was evident. Thus, given the timeline of observations recorded at the site, and local geology, progressive failure along a weak surface, affected by dynamic loading from piling-induced vibrations, may have increased pore pressure and decreased the shear strength of the residual soil and fill. [ABSTRACT FROM AUTHOR]