A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra Leone
Abstract This work focused on three landslide events that have attracted significant public concern due to the associated calamities they recorded in 1945, 2017 and 2019, i.e. the Charlotte, Regent and Madina landslides, respectively. Their geology, tectonics (structural discontinuities) and geomorp...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2021-07-01
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| Series: | Geoenvironmental Disasters |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s40677-021-00187-x |
| _version_ | 1819141948912435200 |
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| author | Yusuf Alhaji Lahai Kelvin F. E. Anderson Yaguba Jalloh Ibrahim Rogers Mohamed Kamara |
| author_facet | Yusuf Alhaji Lahai Kelvin F. E. Anderson Yaguba Jalloh Ibrahim Rogers Mohamed Kamara |
| author_sort | Yusuf Alhaji Lahai |
| collection | DOAJ |
| description | Abstract This work focused on three landslide events that have attracted significant public concern due to the associated calamities they recorded in 1945, 2017 and 2019, i.e. the Charlotte, Regent and Madina landslides, respectively. Their geology, tectonics (structural discontinuities) and geomorphology, i.e. their GTG characteristics were studied to establish links between them and the landslide events. Field surveys were conducted, particularly on the Charlotte landslide, where the identification of geological structures was impeded to an extent by its obliteration by vegetation and sediment accumulations on relatively planar sections of the landslide area. Remote sensing and GIS techniques (earth imagery and drone images) enhanced the mapping and determination of landslides’ geometric and geomorphic parameters. Laboratory analyses of rock and soil samples provided the landslides’ petrological characterisation and were used to determine the particle-size distribution in the slide-prone soil. The study indicated a change in the gabbroic rock composition, variable geomorphological characteristics, and nature/pattern and density of the discontinuities. These factors, to a large extent, determined the nature and magnitude of the rainfall-triggered landslides. Charlotte lithology slightly differed from the other two landslides and recorded higher Silica (Si) and Aluminum (Al) and lower iron (Fe) from X-Ray Fluorescence (XRF) than rocks of Regent and Madina landslides. The study also revealed only a tenuous correlation between rock composition and weathering depth. The slope angles at the landslides’ prominent scarps (depletion zone) are steep (> 45 degrees) with altitudes of approximately 270 m, 200 m and 470 m above sea level for Charlotte, Regent and Madina, respectively. Unlike the Charlotte landslide, both Regent and Madina landslides are active, but geometrically, their area, length and run-out distances have relatively high variance with a coefficient of variance equals to 1. Information derived from this work can help understand the spatial variation in landslide characteristics and develop a susceptibility map. |
| first_indexed | 2024-12-22T12:02:34Z |
| format | Article |
| id | doaj.art-b01881e999d34073bf7be4775589a2aa |
| institution | Directory Open Access Journal |
| issn | 2197-8670 |
| language | English |
| last_indexed | 2024-12-22T12:02:34Z |
| publishDate | 2021-07-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Geoenvironmental Disasters |
| spelling | doaj.art-b01881e999d34073bf7be4775589a2aa2022-12-21T18:26:33ZengSpringerOpenGeoenvironmental Disasters2197-86702021-07-018111710.1186/s40677-021-00187-xA comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra LeoneYusuf Alhaji Lahai0Kelvin F. E. Anderson1Yaguba Jalloh2Ibrahim Rogers3Mohamed Kamara4Department of Geology, Fourah Bay College, University of Sierra LeoneDepartment of Geology, Fourah Bay College, University of Sierra LeoneDepartment of Geology, Fourah Bay College, University of Sierra LeoneSierra Rutile Company LimitedNational Minerals AgencyAbstract This work focused on three landslide events that have attracted significant public concern due to the associated calamities they recorded in 1945, 2017 and 2019, i.e. the Charlotte, Regent and Madina landslides, respectively. Their geology, tectonics (structural discontinuities) and geomorphology, i.e. their GTG characteristics were studied to establish links between them and the landslide events. Field surveys were conducted, particularly on the Charlotte landslide, where the identification of geological structures was impeded to an extent by its obliteration by vegetation and sediment accumulations on relatively planar sections of the landslide area. Remote sensing and GIS techniques (earth imagery and drone images) enhanced the mapping and determination of landslides’ geometric and geomorphic parameters. Laboratory analyses of rock and soil samples provided the landslides’ petrological characterisation and were used to determine the particle-size distribution in the slide-prone soil. The study indicated a change in the gabbroic rock composition, variable geomorphological characteristics, and nature/pattern and density of the discontinuities. These factors, to a large extent, determined the nature and magnitude of the rainfall-triggered landslides. Charlotte lithology slightly differed from the other two landslides and recorded higher Silica (Si) and Aluminum (Al) and lower iron (Fe) from X-Ray Fluorescence (XRF) than rocks of Regent and Madina landslides. The study also revealed only a tenuous correlation between rock composition and weathering depth. The slope angles at the landslides’ prominent scarps (depletion zone) are steep (> 45 degrees) with altitudes of approximately 270 m, 200 m and 470 m above sea level for Charlotte, Regent and Madina, respectively. Unlike the Charlotte landslide, both Regent and Madina landslides are active, but geometrically, their area, length and run-out distances have relatively high variance with a coefficient of variance equals to 1. Information derived from this work can help understand the spatial variation in landslide characteristics and develop a susceptibility map.https://doi.org/10.1186/s40677-021-00187-xGeologyGeomorphological characteristicsMappingPetrological characterisationTectonics |
| spellingShingle | Yusuf Alhaji Lahai Kelvin F. E. Anderson Yaguba Jalloh Ibrahim Rogers Mohamed Kamara A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra Leone Geoenvironmental Disasters Geology Geomorphological characteristics Mapping Petrological characterisation Tectonics |
| title | A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra Leone |
| title_full | A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra Leone |
| title_fullStr | A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra Leone |
| title_full_unstemmed | A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra Leone |
| title_short | A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra Leone |
| title_sort | comparative geological tectonic and geomorphological assessment of the charlotte regent and madina landslides western area sierra leone |
| topic | Geology Geomorphological characteristics Mapping Petrological characterisation Tectonics |
| url | https://doi.org/10.1186/s40677-021-00187-x |
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