Causes and triggers of deep-seated hillslope instability in the tropics - Insights from a 60-year record of Ikoma landslide (DR Congo)

被引：35

作者：

Dille, Antoine ^{[1
,2
]}

Kervyn, Francois ^{[1
]}

Bibentyo, Toussaint Mugaruka ^{[3
]}

Delvaux, Damien ^{[1
]}

Ganza, Gloire Bamulezi ^{[3
]}

Mawe, Guy Ilombe ^{[3
]}

Buzera, Christian Kalikone ^{[3
]}

Nakito, Evelyne Safari ^{[4
]}

Moeyersons, Jan ^{[1
]}

Monsieurs, Elise ^{[1
,5
,6
]}

Nzolang, Charles ^{[3
]}

Smets, Benoit ^{[1
]}

Kervyn, Matthieu ^{[2
]}

Dewitte, Olivier ^{[1
]}

机构：

[1] Royal Museum Cent Africa, Dept Earth Sci, Leuvensesteenweg 13, B-3080 Tervuren, Belgium

[2] Vrije Univ Brussel, Earth Syst Sci, Dept Geog, Pl Laan 2, B-1050 Brussels, Belgium

[3] Univ Officielle Bukavu, Dept Geol, Site Univ Karhale, Kadutu 570, Bukavu, Rep Congo

[4] Ctr Rech Geol & Minieres, Stn Prov Lwiro, BP 7, Bukavu, Rep Congo

[5] Univ Liege, Dept Geog, Clos Mercator 3, B-4000 Liege, Belgium

[6] Fonds Rech Sci FNRS, Rue Egmont 5, B-1000 Brussels, Belgium

来源：

GEOMORPHOLOGY | 2019年 / 345卷

关键词：

Landslide mechanisms and timing; Weathering; Hillslope evolution; Tropical Africa; UAV; Historical aerial photography; WESTERN BRANCH; LANDSCAPE EVOLUTION; GROUND CONTROL; RAINFALL; INITIATION; KINEMATICS; STRENGTH; EROSION; RIFT; EARTHQUAKES;

D O I：

10.1016/j.geomorph.2019.106835

中图分类号：

P9 [自然地理学];

学科分类号：

0705 ; 070501 ;

摘要：

Studying the causes and triggers of landslides is essential to understand the key process of hillslope evolution and the hazards they generate. Such understanding is crucial in tropical areas where landslide impacts are high and on the rise, and the dearth of accurate processes characterisation is large. Here we investigate the timing and the mechanisms of relatively slow-moving deep-seated landslides in weathered tropical environments through the analysis of a landslide located in the Kivu Rift (DR Congo). This landslide, developed in weathered basalt, shows obvious deformation features at its surface indicating large deformations during recent years, making it a unique natural laboratory in an underexplored area. High-resolution topographic data, historical aerial photographs, satellite imagery and careful field investigations are used to detail the landslide mechanisms and investigate failure development over a 60-year record. By confronting rainfall time series and earthquake sequences with the different deformation episodes, we show that the relation between instability triggers and slope failure is not straightforward; e.g., the largest instability occurred at the end of a dry season during a period of relatively low seismicity. Instead of direct influence of external triggers, we show that some phases of instability may be caused by the intrinsic evolution of the hillslope associated with weathered-related weakening of the slope strength through time. Our results question the relative weight of the commonly recognized causes and triggers of slope instability in this area. Analysis of landslide causes and triggers provided here should help improve the understanding of how surface processes influence the pace of hillslope evolution. It also contributes to a more accurate evaluation of the landslide hazard in the area and across other regions where similar environmental conditions are met. (C) 2019 Published by Elsevier B.V.

引用

页数：14

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