The 2011 Civil Engineering Winner - Slope ALARMS

Landslides are a hazard all over the world, killing thousands of people every year and causing expensive damage to critical infrastructure. And, worryingly, partly down to the growing frequency of extreme weather events and uncontrolled development in some of the world’s most populous areas, they are becoming more common.

In many countries, it’s rare for slopes to be routinely monitored due to the high cost of instrumentation. But, in response to calls from the UN for the development of early-warning systems that could be deployed in low-income economies, a group led by Loughborough University has developed a low-cost sensor system that is able to predict whether a landslide is likely to occur.

Working alongside the British Geological Survey and Geotechnical Observations, the Loughborough-led team has developed the Slope Acoustic Landslide Real-time Monitoring System (ALARMS), a sensor-based technology that can be embedded in the soil and that is able to detect the high-frequency acoustic emissions (AE) generated by deforming materials. All materials emit noise when they deform. A significant part of the noise emitted by deforming materials is at a frequency higher than can be detected by the human ear. The Slope ALARMS sensors monitor AE generated as soil grains move against each other. As there is always some initial movement before a landslide occurs, this can be used to provide an early warning. The sensors only detect the high-frequency AE – this reduces false warnings, because everyday noise is excluded. The system is able to compare the frequency of this noise with a set of trigger values and generates an alarm if they are exceeded.