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The Chaos Canyon landslide, which collapsed on the afternoon of 28 June 2022 in Rocky Mountain National Park, presents an opportunity to evaluate instabilities within alpine regions faced with a warming and dynamic climate. Video documentation of the landslide was captured by several eyewitnesses and motivated a rapid field campaign. Initial estimates put the failure area at 66 630 m2, with an average elevation of 3555 m above sea level. We undertook an investigation of previous movement of this landslide, measured the volume of material involved, evaluated the potential presence of interstitial ice and snow within the failed deposit, and examined potential climatological impacts on the collapse of the slope. Satellite radar and optical measurements were used to calculate deformation of the landslide in the 5 years leading up to collapse. From 2017 to 2019, the landslide moved ∼5 m yr−1, accelerating to 17 m yr−1 in 2019. Movement took place through both internal deformation and basal sliding. Climate analysis reveals that the collapse took place during peak snowmelt, and 2022 followed 10 years of higher than average positive degree day sums. We also made use of slope stability modeling to test what factors controlled the stability of the area. Models indicate that even a small increase in the water table reduces the factor of safety to <1, leading to failure. We posit that a combination of permafrost thaw from increasing average temperatures, progressive weakening of the basal shear zone from several years of movement, and an increase in pore-fluid pressure from snowmelt led to the 28 June collapse. Material volumes were estimated using structure from motion (SfM) models incorporating photographs from two field expeditions on 8 July 2022 – 10 d after the slide. Detailed mapping and SfM models indicate that ∼1 258 000 ± 150 000 m3 of material was deposited at the slide toe and ∼1 340 000 ± 133 000 m3 of material was evacuated from the source area. The Chaos Canyon landslide may be representative of future dynamic alpine topography, wherein slope failures become more common in a warming climate. 

The Miocene Columbia River Basalt Group (CRBG) is the youngest and best studied continental flood basalt province on Earth. The 210,000 km3 of basaltic lava flows in this province were fed by a series of dike swarms, the largest of which is the Chief Joseph dike swarm (CJDS) exposed in north- eastern Oregon and southwestern Washington. We present and augment an extensive data set of field observations, collected by Dr. William H. Taubeneck (1923–2016; Oregon State University, 1955–1983); this data set elucidates the structure of the CJDS in new detail. The large-scale structure of the CJDS, represented by 4279 mapped seg- ments mostly cropping out over an area of 100 × 350 km2, is defined by regions of high dike density, up to ~5 segments/km−2 with an average width of 8 m and lengths of ~100–1000 m. The dikes in the CJDS are exposed across a range of paleodepths, from visibly feeding surface flows to ~2 km in depth at the time of intrusion. Based on extrapolation of outcrops, we estimate the volume of the CJDS dikes to be 2.5 × 102–6 × 104 km3, or between 0.1% and 34% of the known volume of the magma represented by the surface flows fed by these dikes. A dominant NNW dike segment orientation characterizes the swarm. However, prominent sub-trends often crosscut NNW-oriented dikes, suggesting a change in dike orientations that may correspond to magmatically driven stress changes over the duration of swarm emplacement. Near-surface crustal dilation across the swarm is ~0.5–2.7 km to the E-W and ~0.2–1.3 km to the N-S across the 100 × 350 km region, resulting in strain across this region of 0.4%–13.0% E-W and 0.04%–0.3% N-S. Host-rock partial melt is rare in the CJDS, suggesting that only a small fraction of dikes were long-lived.