Main Ethiopian Rift landslides formed in contrasting geological settings and climatic conditions
<p>The Main Ethiopian Rift (MER), where active continental rifting creates specific conditions for landslide formation, provides a prospective area to study the influence of tectonics, lithology, geomorphology, and climate on landslide formation. New structural and morphotectonic data from cen...
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| Autores principales: | , , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/3daeb7e272d74a81a21c7a6e008c85f4 |
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| Sumario: | <p>The Main Ethiopian Rift (MER), where active continental
rifting creates specific conditions for landslide formation, provides a
prospective area to study the influence of tectonics, lithology,
geomorphology, and climate on landslide formation. New structural and
morphotectonic data from central Main Ethiopian Rift (CMER) and southern Main Ethiopian Rift (SMER) support a model of progressive change in the regional extension from NW–SE to the recent E(ENE)–W(WSW)
direction, driven by the African and Somali plates moving apart with the
presumed contribution of the NNE(NE)–SSW(SW) extension controlled by the
Arabian Plate. The formation and polyphase reactivation of faults in the
changing regional stress field significantly increase the rocks' tectonic
anisotropy, slope, and the risk of slope instabilities forming.</p>
<p>According to geostatistical analysis, areas prone to landslides in the
central and southern MER occur on steep slopes, almost exclusively formed on active normal fault escarpments. Landslide areas are also influenced by
higher annual precipitation, precipitation seasonality, vegetation density,
and seasonality. Deforestation is also an important predisposition because
rockfalls and landslide areas typically occur on areas with bushland,
grassland, and cultivated land cover.</p>
<p>A detailed study on active rift escarpment in the Arba Minch area revealed
similar affinities as in a regional study of MER. Landslides here are
closely associated with steep, mostly faulted, slopes and a higher density
of vegetation. Active faulting forming steep slopes is the main
predisposition for landslide formation here, and the main triggers are
seismicity and seasonal precipitation. The Mejo area situated on the
uplifting Ethiopian Plateau 60 km east of the Great Rift Valley shows that
landslide occurrence is strongly influenced by steep erosional slopes and a
deeply weathered Proterozoic metamorphic basement. Regional uplift,
accompanied by rapid headward erosion forming steep slopes together with
unfavourable lithological conditions, is the main predisposition for
landslide formation; the main triggers here are intense precipitation and
higher precipitation seasonality.</p> |
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