Unlocking the Style and Timing of Submarine Landslides: Insights From the Tuaheni North Slide, Hikurangi Margin

We investigate the morphology and timing of Tuaheni North, a large submarine landslide within the Tuaheni Landslide Complex on Aotearoa New Zealand's Hikurangi Margin. We show a clear correlation between two major source volumes from Tuaheni North and two downslope mass transport deposits (MTDs), suggesting there were two distinct events. These two stacked MTDs have a distinct intermediate layer, indicating a time gap between the failures. We estimate the age of these two failure events using a novel method based on the gas hydrate stability zone response to sediment cooling. Our results suggest that the northern event is older than the southern, with estimated ages of 37,000 and 23,000 years, respectively, providing a timeline for the Tuaheni North landslide evolution. Our study highlights a contrast between the rapid, abrupt landslide activity at Tuaheni North and the slow, creeping movements of Tuaheni South, revealing distinct behaviors within the same landslide complex.