Vivian Bih Che

Investigating the Management of Geological Hazards and Risks in the Mt Cameroon Area Using Focus Group Discussions

The scientific evaluation of hazards and risks remains a primary concern in poorly known volcanic regions. The use of such information to develop an effective risk management structure and risk reduction actions however also poses important challenges. We here present the results of a series of focus group discussions (FGDs) organised with city councillors from three municipalities around Mt Cameroon volcano, Cameroon. The Mt Cameroon area is a volcanically and tectonically active region regularly affected in the historical past by lava flows, landslides and earthquake swarms, and has a potential for crater lake outgassing. The lower flanks of the volcano are densely populated and the site of intense economic development. The FGDs were aimed at the elicitation of (1) the knowledge and perception of geological hazards, (2) the state of preparedness and the implementation of mitigation and prevention actions by the municipalities, (3) the evaluation of the effectiveness of the structure of communication channels established to respond to emergency situations, and (4) the recovery from an emergency. In all three municipalities stakeholders had good knowledge of the risks, except for processes never experienced in the region. They generally grasped the causes of landslides or floods but were less familiar with volcano-tectonic processes. Stakeholders identified the lack of strategic planning to monitor hazards and mitigate their impacts as a major weakness, requesting additional education and scientific support. Response to natural hazards is mostly based on informal communication channels and is supported by a high level of trust between local scientists, decision makers and the population. Actions are taken to raise awareness and implement basic mitigation and prevention actions, based on the willingness of local political leaders. The strong centralisation of the risk management process at the national level and the lack of political and financial means at the local level are major limitations in the implementation of an effective risk management strategy adapted to local risk conditions. Our case study highlights the need for earth and social scientists to actively work together with national and local authorities to translate the findings of scientific hazard and risk assessment into improved risk management practices.

Socio-political drivers and consequences of landslide and flood risk zonation: A case study of Limbe city, Cameroon

Disaster risk zonation is often proposed as a long-term disaster risk reduction strategy by international treaties and academic research. This strategy has been implemented in the city of Limbe, which is known to be a disaster-prone one. Citizens are forced to settle in unsafe terrains, ranging from wetlands to unstable hillslopes due to the city’s geographical location and economic attraction. Following the fatal landslides and floods in 2001, a local crisis committee identified affected areas and declared them ‘risk zones’ to prevent further exposure. Empirically, this study narrates the production and implementation of risk zonation policy in the city of Limbe. Theoretically, it uses an urban political ecology perspective, which incorporates science and technology studies, post-political theory and disaster research to interpret the drivers and implications of the mismatch between research, policy and action. In this case study, we investigate the implications for disaster risk reduction by describing three underlying socio-political drivers of the risk zonation policy: (i) authoritarian science regime, (ii) post-political discourse, and (iii) blame diversion. We argue that authorities from national to local level use a post-political discourse to promote and implement disaster risk reduction in the city of Limbe through the development and the application of risk zonation policy. As a consequence, risk zonation leads to poor enforcement of the law and corruption, ultimately leading to risk accumulation in this case. This analysis allows us to draw broader conclusions on drivers and implications of the implementation of disaster risk zonation policy in urban areas that are primarily governed hierarchically and prone to corruption.

Geotechnical and Mineralogical Characterisation of Soils from Landslide Scars and Inferred Sliding Mechanism: Case of Limbe, SW Cameroon

The occurrence of landslides in any area may be attributed to the geotechnical, mineralogical and chemical properties of the soils as well as to forces acting on these materials. In this paper, we investigate the role of geotechnical and mineralogical properties of soils in the occurrence of shallow translational landslides in Limbe, SW Cameroon. Laboratory results show that the soils are mainly inorganic silts of medium to high plasticity with clay fraction composed of non-swelling clay minerals. Calculated factor of safety using the infinite slope model for completely saturated soil is greater than 1.5. We therefore propose that failure is generated as a result of fracture enhanced permeability in localized zones of the superficial soils leading to rainwater accumulation and the development of a perched water table in the saprolite from which high positive pore pressure may development and result in the mobilisation of the overlying soil column.