NATIONWIDE EARTHQUAKE RISK MODEL FOR MASONRY BUILDINGS IN MALAWI

Risk-informed decisions are the key to using the limited resources for disaster risk management efficiently. For low-to-middle-income countries that are exposed to seismic hazards, accessibility to quantitative seismic risk decision-support tools is limited. This is particularly important for East African countries, where available seismic data and models are lacking, building and population exposure models are incomplete, and appropriate seismic vulnerability models are not developed. This study presents the most recent development of a nationwide earthquake risk model for masonry buildings in Malawi. Malawi is one of the least developed countries in Sub-Saharan Africa and faces various economic and social problems, including a fast-degrading environment, rapid population growth, and a low-income volatile economy. Due to its location within the East African Rift system, Malawi experienced several moderate earthquakes that caused seismic damage and loss. As part of the PREPARE (enhancing PREParedness for East African countries through seismic Resilience Engineering) project, a new probabilistic seismic hazard model has been developed by taking into account fault-based seismic sources, in addition to conventional areal sources. The most recent 2018 national census data provide more accurate exposure information for Malawian people and their assets at detailed spatial resolutions. From seismic fragility assessment viewpoints, building surveys and experimental tests of local construction materials have been conducted, and new seismic vulnerability functions have been derived. By integrating these new developments on seismic hazard, exposure, and vulnerability modules, a quantitative seismic risk model for Malawi is developed at a national scale. For the rapid computation of seismic risk curves at individual locations, an efficient statistical approach for approximating the upper tail distribution of a seismic hazard curve is implemented. Using this technique, a seismic risk curve for a single location can be obtained in a few seconds, thereby, this can be easily expanded to the whole nation with reasonable computational times. The results from this new quantitative decision-support tool will allow the calculations of annual expected losses for the whole country and provide a sound basis for science-based policies for seismic risk mitigation in Malawi.