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Landslide susceptibility patterns and their implications for erosional amphitheater formation on Bioko Island (Equatorial Guinea)
Journal article   Open access   Peer reviewed

Landslide susceptibility patterns and their implications for erosional amphitheater formation on Bioko Island (Equatorial Guinea)

J. Brauner, M. A. Pando, T. R. Walter, O. A. N. Ela and L. Vanderkluysen
Natural hazards (Dordrecht), v 122(9), p401
01 May 2026
DOI: https://doi.org/10.1007/s11069-026-08110-z
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https://doi.org/10.1007/s11069-026-08110-zView
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Abstract

Earth and Environmental Science Earth Sciences Geophysics/Geodesy Geotechnical Engineering & Applied Earth Sciences Natural Hazards Original Paper Civil Engineering Environmental Management Hydrogeology
Volcanic landscapes undergo rapid morphological change, with landslides representing a key process controlled by volcano-tectonic structures, topography, and climate. In remote regions, limited accessibility hampers systematic investigation of these processes. On Bioko Island (Equatorial Guinea), landslides occur in distinct spatial clusters despite widespread steep terrain, pointing to additional controls and offering an opportunity to examine their geomorphic implications. Using 110 optical satellite scenes acquired between 2015 and 2024, we compiled the first landslide inventory for Bioko, identifying 275 landslides ranging from 463 to 55,076 m2 and covering a cumulative area of 1.7 km2. Most scars exhibit elongated and locally multilobate morphologies consistent with shallow debris slides and debris flows in clay-rich volcanic soils. A Random Forest (RF) classifier was applied to model landslide susceptibility and evaluate spatial controls. High susceptibility is concentrated along the inner caldera walls of Gran Caldera de Luba, fault-influenced summit and upper-flank sectors of Pico Biaó, and the headscarps of erosional amphitheaters on the flanks of Pico Basilé. Permutation importance and partial dependence analyses identify precipitation as the dominant predictor, followed by aspect and proximity to faults, whereas slope primarily represents a geometric precondition rather than a strong spatial discriminator. The close spatial correspondence between high-susceptibility zones and amphitheater headscarps indicates that regressive erosion, facilitated by structural weaknesses and hydrological forcing, plays a central role in shaping the volcanic edifices. Landslide occurrence is therefore spatially focused where structural and climatic controls coincide, rather than reflecting pervasive instability across the island.

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