Monitoring landslides in hazardous terrain using terrestrial LiDAR: an example from Montserrat

Abstract

Listen

Translate article

It is important to monitor unstable slopes to determine where adverse changes in morphology are indicating the likelihood of failure and a consequent risk to life and property. However, where highly unstable slopes need to be monitored, their very nature precludes the use of direct measurement by surveyors and remote means must be used to protect the safety of the survey team. The use of LiDAR (Light Detection and Ranging) enables the accurate location of a network of points that can be used to create a detailed 3D terrain model, or DEM (Digital Elevation Model), of greater coverage and accuracy than conventional methods, with almost complete safety of the operators. There can be few more hazardous situation than that of monitoring a volcanic andesite lava dome for signs of an impending collapse. Partial collapse of a lava dome generates hot, fast-moving pyroclastic density currents, which are categorized as pyroclastic surge or block-and-ash flow deposits based on sedimentary structures. Monitoring in such circumstances requires that measurements are taken from a distance that minimizes the threat from eruption and from asphyxiation by volcanic gases. The method also needs to be rapid to minimize the time spent by the monitoring team in the hazardous zone. The techniques described here are applicable to the monitoring of any unstable slopes and active landslide where hazardous conditions threaten the survey team. Montserrat is a volcanic island of the Leeward Islands in the Caribbean Sea situated 43 km SW of Antigua. The survey was carried out from Perches Mountain, on the margin of the Soufriere Hills volcanic crater (Fig. 1). The survey covered …