Correlation of acoustic emissions with patterns of movement in an extremely slow-moving landslide at Peace River, Alberta, Canada

Abstract

The Peace River region, Alberta, Canada, has experienced extensive landslide activity since deglaciation. Shear zones within weak lacustrine silt and clay layers typically experience continuous creep, damaging highway and utilities infrastructure. However, occasionally, movement accelerates and potentially catastrophic failures occur. Conventional deformation monitoring approaches provide incremental measurements with low temporal resolution and do not necessarily allow rapid changes in stability to be detected and communicated sufficiently in advance to provide early warning. The study objectives were to (i) acquire a long-term dataset of continuous deformation measurements with high temporal resolution of a case study slope in Peace River, (ii) enhance understanding of a typical creeping Peace River slope’s behavior in response to climatic drivers, and (iii) investigate the potential of an acoustic emission (AE) monitoring system to provide early warning of accelerating deformation behavior. ShapeAccelArray (SAA) and AE instruments were installed, in addition to conventional inclinometers and piezometers. Measurements show that the landslide is “extremely slow”, moving on average 5 mm annually, and reveal seasonal activity with periods of acceleration and deceleration driven by pore-water pressures. Measured AE correlated strongly with the rate and magnitude of SAA-measured displacement, demonstrating the potential of the AE technique to warn of accelerating deformation behavior.