The motion mechanism of a boulder transported by landslide

Various soil-rock mixed landslides occur in the natural environment. Carried along in the slide, boulders will eventually come to rest. The origin of boulder motion provides crucial constraints for inferring geological events. To overcome the challenges posed by the limited visibility within landslides and the subsequent difficulty in observing boulder motion, we propose a novel device to measure three-axis acceleration and angular velocity using Inertial Measurement Unit (IMU) technology. By comparing with the traditional high-speed camera, the efficacy of the IMU sphere is validated. In the study of boulder movements within landslides, we employ the IMU sphere to characterize boulders. Through experiments varying two key parameters-the initial position of the IMU sphere and the mass of fine particles-this study identifies three distinct final deposition states of the IMU sphere: separate, partially submerged, and completely submerged. By analyzing the potential and kinetic energy during the sliding process of the IMU sphere, we delve into the combined effects of motion enhancement due to landslide deformation and motion hindrance as the IMU sphere passes through fine particles, thereby revealing the underlying movement mechanisms of boulders within landslides. Analysis of leading wave heights indicates minimal sensitivity to the initial position of the IMU sphere, with the mass of fine particles exerting the primary influence. At last, through a comprehensive analysis of the IMU sphere's motion, a novel positional parameter is introduced, leading to the identification of motion mechanisms and distinct phase diagrams depicting deposition states.