Areas around Lake Kariba experienced five tremors (slight earthquakes) in the first week of April, authorities have revealed.
According to the Zambezi River Authority (ZRA) and Meteorological Services Department (MSD), the tremors were all only felt around Kariba with the epicentre around Kariba Dam. There were no reports of human injury or damage to buildings.
Two of the tremors occurred on 1 and 2 April and measured 4.0 on the Richter scale while the other three were minor ranging from 3.0 to 3.5 in magnitude.
A statement issued by ZRA, the authority responsible for managing the Zambezi River and Lake Kariba read in part:
Two earth tremors or earthquakes with a magnitude of 4.0 were recorded in the Zambezi Valley around Kariba Dam on the 1st and 2nd of April at 7.29 PM and 5.31 PM respectively.
These tremors are a common occurrence in the area around Kariba Dam. The tremors are referred to as load-induced tremors or reservoir-induced tremors in the case of the Kariba Dam and are a result of the earth crust’s response to water load or weight given the size of the dam.
Tremors of this magnitude do not affect the structural integrity of the dam. However, as a precaution, the Kariba Dam is inspected after each event and the instruments record analysed for any anomalous behaviour irrespective of the magnitude.
An analysis of the instrumentation data shows that the dam was not affected which was also corroborated by the visual inspections of the dam appurtenant structures which showed no structural damage to the dam and its related structures.