Exploring Seismic Hazard and Risk in Africa

The Global Earthquake Model (GEM) is leading an initiative to develop open and transparent earthquake risk models for active seismic regions in Africa. Activities involved in the Sub Saharan Hazard and Risk Assessment (SSAHARA) comprises the three fundamental aspects of earthquake risk: the earthquake hazard, the physical risk and the socio-economic vulnerabilities of the countries. They are then integrated to assess the “Integrated Earthquake Risk” of the region, which would guide decision- and policy-making activities to reduce earthquake risk and promote sustainable development.

Under a USAID-funded project, GEM has completed first phase of the project which delivered preliminary risk models for 8 countries in Africa, namely Ethiopia, Uganda, Kenya, Malawi, Rwanda, Mozambique, Burundi and Rwanda. With up to 23 participants from 11 different countries, models, methodologies and results were presented and discussed. Most participant for the first time could prepare their own input models and run risk analysis for their countries. Participants had the opportunity to discuss and update GEM’s mapping scheme used for exposure modelling

GEM is extending its activities to cover all the 26-active seismic countries in Africa in the second phase of its activities. In order to calculate reliable risk metrics for all countries, participants are invited to review the mapping scheme used to compute exposure models.

Exposure Modelling in Africa

Developing exposure models for earthquake risk assessment involves understanding the type of construction exposed to seismic hazard. Within this project, information from census have been utilized to calculate the total number of residential buildings for each country at national and sub-national level. Buildings within a census survey are usually classified according to a number of attributes such as type of roof, floor and material of the walls. Therefore, it is fundamental to establish a link between these attributes and a seismic vulnerability class (mapping scheme). In this context, GEM invites any expert to provide their feedback regarding the most common building classes in each country, according the the building census survey.

Currently, the mapping scheme describes the GEM taxonomy according the wall material. A total of 25 building classes were derived for all the countries. Housing units were distributed to these classes through expert opinion, technical reports, summary statistics, UN-Habitat reports, and peer-reviewed publications covering the region.

An example is provided below for the country of Ethiopia. In the table , the percentage of each building class according to the attributes of the building census is described.