Johannesburg - An earth tremor which hit parts of Gauteng and the North West was recorded at 4.6 magnitude, the Council for Geoscience (CGS) said on Monday.The tremor, which was 2km deep, was recorded around 05:08 on Monday. It originated near a gold mining area in Klerksdorp, in the North West.The CGS's Michelle Grobbelaar told News24 that in 2005 and 2014, the same region had experienced magnitude 5.3 and 5.5 earthquakes respectively."This earthquake was smaller than them and thus not intense," she said.She said that SA was a low-to-moderate seismically active region, which meant that it generally experienced a number of small earthquakes, and occasional larger ones."Through our monitoring of the seismicity with the national seismograph network, we have mapped the seismicity of the country and it is evident that more than 80% of the seismicity within the country is located in and around the mining regions."ResearchShe said that South Africa's largest earthquake had been in the Ceres/Tulbagh region in 1969.Residents in and around Johannesburg turned to social media to share news of apparent earth tremors at the weekend.Residents in Soweto and Westdene told News24 on Saturday night that their homes had shaken briefly. Others reported that they felt a second tremor after the first one.In the early hours of Monday morning, residents of Klerksdorp and surrounding towns were also woken by an earth tremor.Grobbelaar said the CGS was planning to send a team to the area to interview residents about the tremor as part of the council's research."This information is very useful to us," she said.