18 Jan 2021

18 Jan 2021

Review status: a revised version of this preprint is currently under review for the journal NHESS.

Main Ethiopian Rift landslides formed in contrasting geological settings and climatic conditions

Karel Martínek1,2, Kryštof Verner2,3, Tomáš Hroch2, Leta A. Megerssa3,2, Veronika Kopačková2, David Buriánek2, Ameha Muluneh4, Radka Kalinová3, Miheret Yakob5, and Muluken Kassa4 Karel Martínek et al.
  • 1Institute of Geology and Palaeontology, Faculty of Science, Charles University, Albertov 6, Prague, 12843, Czech Republic
  • 2Czech Geological Survey, Klárov 3, 118 21 Prague, Czech Republic
  • 3Institute of Petrology and Structural Geology, Faculty of Science, Charles University, Albertov 6, Prague, 12843, Czech Republic
  • 4School of Earth Sciences, Addis Ababa University, Arat Kilo, 1176, Addis Ababa, Ethiopia
  • 5Geological Survey of Ethiopia, CMC road, Bole Keb.10/Wor.6, POBox: 2302, Addis Ababa, Ethiopia

Abstract. 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 CMER and 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 Somalian plates moving apart with the presumed contribution of the NNE(NE) – SSW(SW) extension controlled by the Arabic Plate. The formation and polyphase reactivation of faults in the changing regional stress-field significantly increase the rocks' tectonic anisotropy and the risk of slope instabilities forming.

According to geostatistical analysis landslides in the central and southern MER occur on steep slopes, almost exclusively formed on active normal fault escarpments. Landslides are also influenced by higher annual precipitation, precipitation seasonality, vegetation density and seasonality.

A detailed study on active rift escarpment in the Arba Minch area revealed similar affinities as in regional study of MER. Landslides here are closely associated with steep, mostly faulted, slopes and a higher density of vegetation. Active tectonics and seismicity are the main triggers. The Mejo area situated on the uplifting Ethiopian Plateau 60 km east of the Rift Valley shows that landslide occurrence is strongly influenced by steep erosional slopes and deeply weathered Proterozoic metamorphic basement. Rapid headward erosion, unfavourable lithological conditions and more intense precipitation and higher precipitation seasonality are the main triggers here.

Karel Martínek et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2020-420', Anonymous Referee #1, 03 Feb 2021
    • AC1: 'Reply on RC1', Karel Martínek, 13 Apr 2021
  • RC2: 'Comment on nhess-2020-420', Anonymous Referee #2, 08 Feb 2021
    • AC2: 'Reply on RC2', Karel Martínek, 13 Apr 2021

Karel Martínek et al.

Karel Martínek et al.


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Short summary
This study combines field geological and geohazard mapping with remote sensing data. Geostatistical analysis evaluated precipitation, landuse, vegetation density, rock mass strength and tectonics. Contrasting tectonic and climatic setting of the Main Ethiopian Rift and uplifted Ethiopian Plateau have major impact on the distribution of landslides.