A common nomenclature of landslide geometry is the basis for describing and understanding landslides. A landslide is defined as the movement of a mass of rock, debris, or earth down a slope – a phenomenon in 3D space.

However, in the current international nomenclature, landslide geometry is defined in 2D space, therefore, it cannot effectively reveal landslide movement characteristics. Traditional nomenclature defines landslide length (L) and width (W) in 2D space (in a planar or sectional view), which is inevitably misleading when used for understanding landslides.

Prof. LAN Hengxing’s team at the Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of Sciences, and their cooperators proposed an upgrade of the widely-used international nomenclature, in which landslide geometry is defined in 3D space, thus favors a better understanding of landslide motion processes. This work was published in Landslides.

Researchers put forward to define and measure landslide length, width, and their ratio (aspect-ratio, ε) in 3D space. They found that measurements in 3D space can derive true “path-dependent” geometric parameters, which reveal landslide movement characteristics, while traditional measurements in 2D views only generate “path-independent” parameters.

“We developed an automatic approach for measuring those “path-dependent” landslide geometric parameters, and implemented the approach in an open-source software Automatic Landslide Profile Analysis (ALPA) ,” Dr. LI Langping said.

The study is also a recent progress of the Commission 37 on Landslide Nomenclature of the International Association for Engineering Geology and the Environment (IAEG). Upon hearing about this study, Prof. Rafig Azzam, President of the IAEG said “Congratulation to you and to the C37 team. IAEG is proud about the active members and their contribution to our discipline and society”.

The study was done in collaboration with the Geodynamics Research Center LLC, Russia and the University of Alberta, Canada.

The work was supported by the Second Tibetan Plateau Scientific Expedition and Research Program, the National Natural Science Foundation of China and the Strategic Priority Research Program of Chinese Academy of Sciences.

Reference:
Li, L.-P., Lan, H.-X., Strom, A., Macciotta, R., 2022. Landslide length, width, and aspect ratio: path-dependent measurement and a revisit of nomenclature. Landslides.

Upgrade of the widely-used international nomenclature of landslide geometry. (Image by Prof. LAN’s team)