The Council of Geoscience (CGS) confirmed that a seismic event measuring a local magnitude of 3.3 occurred on Friday morning in the Welkom gold mining region. The event was recorded at 09:17 and the epicentre was located approximately 5km southwest of Odendaalsrus, the CGS said.
What was recorded and where
The South African National Seismograph Network (SANSN) registered the local magnitude as 3.3. An independent platform that tracks seismic activity, VolcanoDiscovery, said the event would likely have produced only weak shaking for most people. The platform also logged submissions from the public: about 20 reports were received from locations across South Africa relating to this event.
| Item | Detail |
|---|---|
| Date and time | Friday, 09:17 (local time) |
| Magnitude | 3.3 (local magnitude) |
| Epicentre | ~5km southwest of Odendaalsrus (Welkom gold mining region) |
| Public reports received | ~20 reports via VolcanoDiscovery |
| Reported distances felt | Approximately 5.8km to 8.8km from epicentre |
Residents describe short, distinct shaking
People in the area described feeling the tremor at varying distances from the epicentre. Reports collected by the tracking platform and referenced by the CGS included accounts of brief shaking lasting about 5 to 7 seconds. One person who was 5.8km from the epicentre said they were indoors and that their house and doors shook, adding they were given a fright. Another report from a person 7.7km away said it felt like the earth might give way beneath their feet. A third report from 8.8km away described creaking roofs and vibration.
“Could hear it getting closer. I was indoors and house shook and windows and doors rattled. Got quite a fright, and it lasted about 5–7 seconds.”
Context for Welkom and surrounding mining towns
The epicentre lies within the established gold mining belt that includes Welkom and neighbouring towns such as Odendaalsrus. Seismic activity in this region is monitored by the CGS and national seismograph networks because mining operations can alter stresses in rock and occasionally contribute to local seismic events. The CGS statement did not attribute this particular event to mining nor provide a cause beyond confirming the event's time, location and magnitude.
While a magnitude of 3.3 is considered light and typically causes only minor, local effects — rattling windows, creaking roofs, and short-duration shaking — it is enough to unsettle residents and prompt enquiries to authorities, especially in mining communities where people are accustomed to both natural and induced seismic events.
What residents and local authorities should know
- Authorities logged the event and its basic parameters: time, epicentre and magnitude, but no damage reports were cited in the CGS statement.
- Residents who felt shaking are encouraged to report observations to the CGS or relevant tracking platforms to help build a clearer picture of felt intensities and impacts.
- Local mines, municipal emergency services and the CGS remain the primary agencies for follow-up should any physical damage or injuries be reported.
The CGS and SANSN provide routine monitoring of seismicity in the Free State goldfields. For now, the recorded 3.3 event is a reminder that the subterranean environment beneath Welkom and its neighbouring towns remains dynamic, and that continued monitoring and public reporting help authorities assess any changes in seismic behaviour.
No further information on damage or injuries was included in the CGS report; the national seismograph network's magnitude reading and the public reports recorded by VolcanoDiscovery form the basis of the confirmed details.
