The Geomorphic Effectiveness of Landslides

• Published in: Journal of geophysical research. Earth surface 2023-12, Vol.128 (12), p.n/a
• Main Authors: Dente, E., Katz, O., Crouvi, O., Mushkin, A.
• Format: Article
• Language: English
• Subjects: Cliffs; coastal cliff; Distribution; earthquake; Earthquake damage; Earthquakes; Effectiveness; Environmental changes; Environmental conditions; Evolution; geomorphic effectiveness; Geomorphology; Inventories; Landscape; Landslides; Landslides & mudslides; Lidar; Lithology; Precipitation; Probability theory; Rainfall; Seepage; Seismic activity
• ISSN: 2169-9003; 2169-9011
• DOI: 10.1029/2023JF007191

Landslides are widely recognized as key components of landscape evolution in areas of steep topography. Here, we present a new framework for examining landslide inventories in the context of the volume‐based impact that different landslide sizes have on shaping the landscape, that is, their geomorphic effectiveness (GE). Focusing on an actively retreating coastal cliff in the Eastern Mediterranean and utilizing a LiDAR‐derived inventory of over 1,100 cliff landslides that occurred between 2014 and 2019, we show that segments of the cliff are characterized by two principal types of GE distributions: (a) A “humped” GE distribution where the accumulated erosion volume of the largest and rarest collapses in the inventory is similar or lower than that of more frequent, mid‐range collapses and (b) Nearly monotonically increasing GE distribution where the cumulative volume of larger collapses consistently surpasses that of smaller magnitude collapses. Regardless of the GE distribution type, we found that the cumulative geomorphic impact of the small and most probable collapses was negligible. Extending this new GE framework to 9 other previously published landslide inventories (coastal and mountainous), we demonstrate that precipitation and seepage‐induced landslide inventories are commonly characterized by monotonic‐type GE distributions, dominated by large landslides (>10−1 of the volume of the largest landslide), and that hump‐shaped GE distributions, dominated by more frequent mid‐size landslides, commonly occur under “dry” triggers (e.g., earthquakes). We propose that the humped GE distribution could reflect the lack of deep mechanical weakening, which exerts a higher probability of the largest landslides in the inventories triggered by “wet” factor. Plain Language Summary Landslides are a vital component of landscape evolution and can cause catastrophic damage to infrastructure and human life. While larger landslides hold the potential to be the most destructive and effective events sculpting the landscape, their occurrence is relatively rare compared to smaller landslides that may be less destructive but occur more frequently. This study presents a new approach that examines the accumulated impact of different landslide magnitudes as a function of volume and frequency of occurrence. We suggest that the lithological setting and the triggering mechanism of landslides can determine which landslide magnitude will be more impactful. In all the analyzed landslid