Landslide analysis combining laser scanning and photogrammetry

Abstract

After a sequence of weeks of heavy raining, a catastrophic mass movement occurred in the parish of Palmeira de Faro, Esposende (N Portugal) on November 23, 2022. The collapsed slope presented a maximum height of about 21 m and a length of 45 m. In order to document and analyse this case from the geotechnical perspective, a general survey was devised including the use of aerial photography, laser scanning and conventional topographic survey methods. The results obtained showed that these techniques provide very accurate and abundant information that is essential to support a comprehensive documentation of the features and variables of the slope. The mechanisms involved in this catastrophic collapse are still under investigation, and causes such as the excessive rainfall in the previous months or geologic conditions are still being considered, although currently the existing information seems to indicate for a combination of debris flow / rock slide driven event.