Seismic risk mitigation for the east African countries - case study: Salima, Malawi

Malawi is located in the Rift area of East Africa and is classified as one of the poorest countries in the world. Scarce seismic awareness and lack of economic resources have a negative impact on the technical practice adopted to build local houses, which results in inadequate resistance against seismic loads. The poor construction techniques, together with the absence of quality control, underline an urgent need to evaluate the seismic behaviour of local buildings to make informed decisions to improve resilience through risk mitigation plans. This report presents a strategy to mitigate seismic risk with low-cost
engineering solutions considering how the shortcomings of the poorly built informal masonry houses in Malawi affect their seismic response and failure modes. The proposed strategy is applied to Salima, a city in the central region of Malawi, which was severely damaged by an earthquake in 1989, causing about 50,000 homeless people. To characterize the geometric and structural characteristics of the Malawian buildings and to identify the resistance of construction materials, formal and informal settlements in Salima
are surveyed, and experimental works are carried out on local masonry and typical mortars adopted in the construction practice. The acquired information is employed to derive fragility curves for the building typologies proposed for Malawi by the classification of the World Housing Encyclopaedia (Novelli et al. 2018). The effectiveness of different mitigation solutions for enhancing the seismic resilience in Salima is also discussed and evaluated by comparing the building performance before and after the retrofitting
measures are applied to the existing houses. The case study shows that low-cost
engineering interventions are remarkable solutions to mitigate the seismic risk in the countries of the East African Rift region.