I assume that soil saturation affects the transmission of sound. Make a birdhouse on a post, with a solar panel roof and a subsonic transducer in the base. Put a sparse array of these landslide detecting birdhouses (LDBs) on an experimental hillside. Tell an AI to learn which change in sound transmission precedes landslides. Wait for storms, or speed things up with sprinklers. Once you establish predictive power, add a system that makes noise and sends text messages to warn people and notify authorities.