Johannesburg - Four earthquakes were recorded around Gauteng, the North West province and Limpopo on Wednesday, the Council for Geosciences reported on Thursday.
The first was at 13:28 in the Gamoep area of Limpopo and measured 2.4 on the Richter scale, with a depth of 5km.
The second earthquake was at 19:.34 in Gauteng, along the Roodepoort mining belt, west of Johannesburg. It measured 2.4 on the Richter scale and was recorded with a depth of 2km.
Patrick Malaza, chief financial officer at Rand Central Gold mines said they felt nothing and operations had not been affected.
"I didn't even spill my coffee," he quipped.
However, that quake solicited a number of calls to the council by worried residents around Johannesburg wanting to know what was happening.
A third earthquake was recorded in the area of the West Rand gold mines in the North West at 23:42, measuring 2.9 with a depth of 2km.
A fourth was recorded at 23:49 in the same area, measuring 2.9 with a depth of 2km.
Increase in quakes
Michelle Grobbelaar, manager of the seismology unit at the council said on Thursday there had been an increase in quakes in the Johannesburg region, which they are trying to get to the bottom of.
"We have been noticing it not just through our measuring, but also through the public phoning us to tell us about them," said Grobbelaar.
Grobbelaar said the council is trying to increase the number of seismograph stations in the Johannesburg area, and encourage the public to fill in their online questionnaire to let them know about an event.
Their initial feeling is that the quakes are related to mining activity and the number of abandoned mines in Johannesburg. Eighty percent of the region's quakes occur in gold mining areas.
The build up of stresses in the earth's crust needs to be released along a weak point and where areas have been excavated, there are empty spaces where there used to be rock.
"If you have excavated all that solid rock and have empty spaces, the earth has to accommodate for that," said Grobbelaar.
Earthquakes could also occur in areas where dams or reservoirs have built on spaces where there was originally nothing, putting tons of water onto the land mass.
"This creates stresses and lubricates the faults, now we have faults that can move."
Records
Equipment to measure earthquakes was only installed in South Africa in the 70s so researchers are trying to find ways of gathering older written records like journals to find out whether they are getting bigger or smaller in South Africa.
With the tragic images of the Haiti earthquake still fresh, Grobbelaar said that South Africans should not panic about a similar occurrence here.
"Generally, a 2.8 shouldn't cause any structural damage. But in the 3's you can expect more structural damage."
"In gold mines if the guys are down there, that's pretty serious."
Spokespeople for other mines in the quake areas were not immediately available to say if they had been affected, but during parliamentary questions, Mineral Resources Minister Susan Shabangu said "fall-of-ground" accidents remained the predominant cause of deaths in the industry.
Grobbelaar said South Africa was blessed with "modest" seismicity compared with countries like Japan or Chile.
Asked whether Wednesday night's quakes could be a predictor of something more serious she said: "I don't think people should be worried. We are looking into the Johannesburg ones though, because there is an increase."
"The others are running their normal course, it's to be expected."
To report an earthquake in your area contact the council at 012-841-1911 or complete a questionnaire on their .
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The Hawks are investigating whether Eugene Terre Blanche's death had been a sex crime, says spokesman Musa Zondi.
However, he said this was not the only possibility the Directorate for Priority Crime Investigations was investigating.
"We are looking into that and everything else," said Zondi.
The Hawks, he said, were considering other possibilities that may have lead to the murder of Terre Blanche, including that of a labour dispute.
He said clothes that were worn by the two suspects, 28-year-old Chris Mahlangu and a 15-year-old boy, who cannot be named, on the day of the murder were sent for forensic investigations.
He denied that a used condom was found in the room where Terre'Blanche's body was found.
Earlier when Sapa phoned North West police spokeswoman Adele Myburgh who was first to quash the allegations that a used condom had been found on the scene, she said she was taken off the Terre Blanche case.
She said that she would not give media comment about the case as part of an "internal" process, which she said "I respect".
Myburgh had come out strongly denying the allegations.
"There was no condom found on the scene of the late Mr Eugene Terre Blanche. I'm prepared to put my neck in a guillotine and you can have a go at it if I have been lying," Myburgh had told Sapa on Saturday.
Meanwhile, the Sunday Times newspaper reported that Mahlangu, through his lawyer, claimed to have been sodomised by Terre Blanche.
The newspaper quoted attorney Puna Moroko as saying: "My instructions from my client are that there was some sodomy going on and it sparked the murder of Mr Terre'Blanche. This is going to form part of our defence during trial".
Moroko also claimed that Terre Blanche tried to get the accused drunk before he allegedly tried to have sex with them.
It was previously reported that Terre Blanche had bought whisky and several bottles of cider on the day he was murdered.
Eugene Terre Blanche was murdered on April 3 on his farm outside Ventersdorp.
Mahlangu, and the minor, have since been charged with murder, house breaking and robbery with aggravating circumstances and attempted robbery with aggravating circumstances.
They appeared in court on Tuesday and their case was postponed to April 14. The two had not yet pleaded to the charges.
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