Johannesburg - An earth tremor measuring four on the magnitude scale was recorded in Johannesburg on Monday, the Council for Geoscience said.
Manager of the seismology unit Michelle Grobbelaar described the tremor as "quite a big guy".
The preliminary analysis indicated the epicentre was near the University of Johannesburg just before 10am.
One Twitter user said: “There was a tremor in JHB about 20mins ago. Building shook for about a minute. I'm still shaking”.
The City of Johannesburg and Weather SA were also among tweeters who said they had felt the earth move.
“The #tremor was also felt in parts of northern & southern JHB. Lasted for around 10-15 seconds,” Weather SA tweeted.
Another tweeted: “Oh, so the tremor thing happened all over Joburg? Lol I thought it was just because of the construction in our office park”.
IOL staff in the Johannesburg CBD said the tremor was strong and lasted a couple of seconds. Windows and office equipment were noticeably rattled by the tremor although no damage was done.
Quakes, or tremors, are the result of a stress build-up in the earth's crust. When the stress becomes too great, it is released in the form of a quake, usually on a geological fault line.
Grobbelaar said previously that after an earthquake, it was a rule of thumb that another tremor of similar magnitude could often be expected in the same region, but seismologists could not predict when this would happen. - IOL and Sapa