Own Correspondent|Two earth tremors or earthquakes with magnitude 4.0 were recorded in the Zambezi Valley around Kariba Dam on the 1st and 2nd April 2020 at 19.29 hours and at 17.31 hours respectively.
The epicentre of the April 1st earthquake was approximately 3 km south-west of the Spurwing Island Lodge or 27 km south of the Kariba Dam and the epicentre of the April 2nd earthquake was approximately 65 km east of the Kariba Dam wall.
Besides the vivid scientific explaination of the two earthquakes, local Tonga people on both sides of the dam strongly believe that the tremors were movements of the revered Nyami Nyami spirit at the lake.
The Nyami Nyami, otherwise known as the Zambezi River God or Zambezi Snake spirit, is one of the most important gods of the Tonga people. Nyami Nyami is believed to protect the Tonga people and give them sustenance in difficult times. The River God is usually portrayed as male.
These tremors are a common occurrence in the area around the Kariba Dam.
Scientifically, the tremors are referred to as load induced tremors or specifically reservoir induced tremors in the case of the Kariba Dam and are a result of the earth crust’s response to the water load or weight of water given the size of the dam.
These tremors have been occurring since 1963 when the Kariba Dam started filling. Over 1000 tremors of magnitude 4.0 as the most recent tremors occurred since filling of the dam in 1963.
African mythology of the local Tonga tribe of the Zambezi Valley states that Nyami Nyami the River God who lives in Lake Kariba is believed to be a serpent-like creature. He is said to be about three metres wide, but nobody dares to guess at his length.
Legends has it that the water stains red when he swims past. Chief Sampakaruma saw him on two occasions many years ago, but the river god has been in hiding since the white men arrived in the country.
According to African mythology he lived under a large rock close to the present day Kariba dam wall. No tribesman would venture near it those few who did were sucked down with their canoes in the whirlpools and never seen again. They called the rock Kariwa, the “trap” and hence the name of the lake, Kariba.
The rising water of lake Kariba covered the rock Kariwa and it now lies 30 metres below the surface annoying Nyami Nyami. The Tonga people also believe that Nyami Nyami is married and that the building of Kariba Dam wall would separate him from his wife, this would anger him greatly and the river god threatened the peace of the valley.
Traditionalists believe that the latest tremors were not an earthquake but it was the Nyami Nyami moving at the base of the dam.
The Kariba Dam’s water level ended last year at its lowest in 23 years, but in the last three weeks data from three major river flow stations along the Zambezi River, show a tremendous water flow towards the giant lake.
Kariba Dam is Zimbabwe’s largest power station, with capacity to produce 1 050MW, but is currently generating electricity at curtailed level due to critically low water levels following the drought experienced in the catchment area of the dam’s main feeder river.
When the water levels dwindled last year, the traditionalists believed that the Nyami Nyami was angry.
It is the traditional role of tribal elders and spirit mediums to intercede on behalf the inhabitants of the river valley when Nyami Nyami is angered.
What’s surprising is that the tremors of this magnitude have never affect the structural integrity of the dam. However, as a precaution, the Kariba Dam is inspected after each event and the instruments records analysed for any anomalous behaviour irrespective of the magnitude. The dam was inspected on the 2nd and 3rd April 2020 and the dam instrumentation data was analysed. Analysis of instrumentation data showed that the dam was not affected which was also corroborated by the visual inspections of the dam and its appurtenant structures which showed no structural damage to the dam and its related structures.