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Investigation of the directional effect on low cost houses due to the 2014 Orkney earthquake.

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The Orkney earthquake on the 5th August 2014 caused major damages to houses in Orkney and surrounding areas. A post field assessment was carried out to determine the amount of damage caused by the earthquake. The Khuma township near Stilfontein was the most affected area where more than 600 houses were damaged. The damage caused by the 2014, Orkney earthquake was made worse by the poorly constructed low-cost houses in Orkney and the surrounding townships (Khuma, Kanana and Jouberton). These houses were vulnerable to earthquake damage. This study sought to determine the effects of additional factors that contribute to earthquake damage such as: building excitation angle, exposure of building weak points to earthquake direction and building finishes. In this study, results show that building excitation angle, exposure of weak points and finishes either plastered or un-plastered can contribute to the damage and vulnerability of a building during an earthquake tremor. Buildings of excitation angles between 0° - 30° and 61°- 90° had more damages compared to houses that had an excitation angles of between 31°- 60° for all 3 townships (Khuma, Kanana and Jouberton). The excitation angle of 0°- 30° recorded the highest damage grade, followed by excitation angle of 61° - 90°. The least amount of damage was observed for the excitation angle of 31° - 60°. The reason for these effects was that for the excitation angle of 0° - 30° and 61° - 90°, two or more building walls were perpendicular to the earthquake direction hence the building becomes vulnerable to toppling. Furthermore, houses that had weak points (windows and doors) exposed to the line of sight from the epicentre had reported more damages than houses that have no weak point exposed to the line of sight from the epicentre. Buildings that were completed with plaster were more resistant to earthquake damage than buildings that were un-plastered. The findings in this study can used be to establish fundamental building vulnerability properties for low-cost developments which will help to improve the construction of low-cost houses and reduce their vulnerability to earthquake damage and protect human life.


Masters Degree. University of KwaZulu- Natal, Durban.