The 2017 Regent Landslide, Freetown Peninsula, Sierra Leone

Abstract

At 06:50 on Monday 14 th August 2017, a hillslope on the Freetown Peninsula, Sierra Leone, collapsed, sending 300,000 m 3 of debris into the flooded valley below. As this debris mixed with floodwater it became a sediment-laden flood which entered a drainage channel and travelled 6 km to the coastline. The event destroyed nearly 400 buildings, claimed the lives of an estimated 1,100 people and affected approximately 5,000 people. The mechanism was a two-stage rainfall-triggered landslide followed by a channelised debris-laden flood. The processes were similar to the nearby 1945 event in Charlotte, which killed at least 13 people.

Lion Mountain Landslide in Non-urbanized Terrain: Changing the Myth of Landslide Occurrence in Western Sierra Leone

“…Historically, landslide events have occurred in forested area (Redshaw et al, 2019), including an area formally designated as the Western Area Peninsula Forest (Sesay, 2005). Recent landslide inventory conducted through field surveys and the exploration of Google Earth satellite images (-accessed in 2019 and 2020) in the area represented by Figure 1, has shown greater percentage of landslide scars in forested area than the urbanized zones (Lahai, 2020).…”

A comparative Geological, Tectonic and Geomorphological assessment of the Charlotte, Regent and Madina Landslides, Western Areas, Sierra Leone

“…This is also supported by the exclusion of localized landslide crises in the International Emergency Database (EM-DAT) and the Global Disaster Identifier (GLIDE), despite its serious impacts; indicating a dearth in landslide knowledge in this part of the world. In effect, excluding work by Thomas (1983Thomas ( , 1994Thomas ( & 1998 which concentrates only on the central highlands, records show that, the only studies done are by Cui et al (2019); Redshaw et al (2019) and Lahai and Lahai, (2019), and these are focused on the Regent landslide. It is therefore clear that, the influences of geology, geomorphology and geological structures on landslide occurrences have neither been studied nor well defined in the country (landslide characteristic data remain poor or inexistent).…”

“…The hilly and mountainous central part of the Freetown Layered Complex, has documented more landslide events (FCC, 2014), and caused colossal losses (UNDP&EPA, 2017) than any other place within the Layered Complex. One such incident was the Regent landslide which affected the Sugarloaf Mountain, and claimed more lives than anywhere in the world in 2017 (Redshaw et al, 2019). This slide like other landslide events is influenced by multitude of factors.…”

“…Despite the socio-economic and geomorphologic impacts associated with landslides (Ngeku and Mathu, 1999;Ngeku et al, 2004 andJacobs et al, 2016), which are expected to increase with global climate change (Nugraha et al, 2015), studies are still rare in the Africa continent ( The situation is even worst in Sierra Leone, which has very limited and restricted scientific landslide studies (e.g. Thomas, 1983Thomas, , 1994Thomas, & 1998Cui et al, 2019, Redshaw et al, 2019; and Lahai and Lahai 2019), amidst a surge of landslides in its capital city. This is also supported by the exclusion of localized landslide crises in the International Emergency Database (EM-DAT) and the Global Disaster Identifier (GLIDE), despite its serious impacts; indicating a dearth in landslide knowledge in this part of the world.…”

“…Clays at Regent landslide are much more visible in joints, fractures etc, as a result of chemical weathering and breakdown of plagioclase feldspars, to form clay minerals (secondary minerals). The thickness of soil and rock weathering profiles at the three sites are locally affected by the following; bedrock texture, geochemistry, mechanical discontinuities (joints, faults and shears) and the degree/depth of laterization and saprolite development(Redshaw et al, 2019), and is much pronounced in the Regent landslide.4.2.2 Tectonics (Geological structures)Discontinuities and lineaments are used interchangeably in this study to describe faults, cracks andjoints. They are linear structures that represent mirror image of subsurface condition (O'Leary et al, 1976).…”