Objective versus subjective landslide risk: A case of Cache Creek Landslide in California

Landslides pose a significant threat to infrastructure, communities, and human life throughout the world. A critical first step toward landslide risk reduction lies in risk awareness and proactive risk mitigation. However, in some cases, a lack of awareness or underestimation of landslide risks among communities and local stakeholders can lead to increased losses from potential landslide events. This study explores divergences between objective and subjective landslide risk assessments, focusing on the Cache Creek Landslide in Lake County, California. The landslide is in a region highly susceptible to various hazards. For the objective assessment of landslide risk, this study utilized imagery from Google Earth and publicly available digital elevation models to track the movements of the Cache Creek Landslide since 1953. Landslide movements over time were analyzed regarding cascading hazards such as heavy precipitation, post-wildfire conditions, and seismic activity. For subjective landslide risk assessment, a survey was conducted among adult residents throughout Lake County. Survey results revealed that most of the residential community surrounding Cache Creek is predominantly unaware of the landslide and the cascading hazards it poses. We argue that engineers and scientists must better convey disaster potential to the public to motivate community and governmental response. These differences in objective findings and subjective perceptions have significant implications, including potential delays in implementing necessary mitigation strategies and increased vulnerability of at-risk populations. Addressing these gaps is essential to enhance landslide risk awareness and foster proactive measures, ultimately reducing the devastating impacts of landslides in vulnerable communities.