We describe and model the evolution of a recent landslide, tsunami, outburst flood, and sediment plume in the southern Coast Mountains, British Columbia, Canada. On November 28, 2020, about 18 million m³ of rock descended 1,000 m from a steep valley wall and traveled across the toe of a glacier before entering a 0.6 km² glacier lake and producing >100‐m high run‐up. Water overtopped the lake outlet and scoured a 10‐km long channel before depositing debris on a 2‐km² fan below the lake outlet. Floodwater, organic debris, and fine sediment entered a fjord where it produced a 60+km long sediment plume and altered turbidity, water temperature, and water chemistry for weeks. The outburst flood destroyed forest and salmon spawning habitat. Physically based models of the landslide, tsunami, and flood provide real‐time simulations of the event and can improve understanding of similar hazard cascades and the risk they pose.

The stability and deformation behavior of high rock slopes depends on many factors, including geological structures, lithology, geomorphic processes, stress distribution, and groundwater regime. A comprehensive mapping program is, therefore, required to investigate and assess the stability of high rock slopes. However, slope steepness, rockfalls and ongoing instability, difficult terrain, and other safety concerns may prevent the collection of data by means of traditional field techniques. Therefore, remote sensing methods are often critical to perform an effective investigation. In this paper, we describe the application of field and remote sensing approaches for the characterization of rock slopes at various scale and distances. Based on over 15 years of the experience gained by the Engineering Geology and Resource Geotechnics Research Group at Simon Fraser University (Vancouver, Canada), we provide a summary of the potential applications, advantages, and limitations of varied remote sensing techniques for comprehensive characterization of rock slopes. We illustrate how remote sensing methods have been critical in performing rock slope investigations. However, we observe that traditional field methods still remain indispensable to collect important intact rock and discontinuity condition data.

The stability and kinematics of rock slopes are widely considered to be functions of lithological, structural, and environmental features. Conversely, slope damage features are often overlooked and considered as byproducts of slope deformation. This paper analyzes and discusses the potential role of slope damage, its time-dependent nature, and its control on both the stability of rock slopes and their kinematics. The analysis of several major landslides and unstable slopes, combined with a literature survey, shows that slope damage can play an important role in controlling short- and long-term slope stability. Seasonal and continuously active events cause permanent deformation within the slope due to the accumulation of slope damage features, including rock mass dilation and intact rock fracturing. Rock mass quality, lithology, and scale control the characteristics and complexity of slope damage, as well as the failure mechanism. The authors propose that the role of slope damage in slope kinematics should always be considered in slope stability analysis, and that an integrated characterization–monitoring–numerical modelling approach can enhance our understanding of slope damage, its evolution, and the controlling factors. Finally, it is emphasized that there is currently a lack of guidelines or frameworks for the quantitative assessment and classification of slope damage, which requires a multidisciplinary approach combining rock mechanics, geomorphology, engineering geology, remote sensing, and geophysics.