1969 Tulbagh earthquake

Earthquake in South Africa July 2024 1969 Tulbagh earthquake South Africa 1969-09-29 20:03:30 805003 iscgem805003 1969 09 29 y 22:03 SAST 6.3 w 15 km mi 0 on -33.268 19.386 region:ZA_type:event inline,title Strike-slip VIII Many rockslides 12 dead The 1969 Tulbagh earthquake occurred at 20:03:33 UTC on 29 September. It had a magnitude of 6.3 w yes and a maximum felt intensity of VIII (Severe) on the Modified Mercalli intensity scale. It caused widespread damage in the towns of Ceres, Tulbagh and Wolseley and led to 12 deaths.Green R.W.E. Bloch S. 1971 The Ceres, South Africa, earthquake of September 29, 1969. 1. Report on some aftershocks Bulletin of the Seismological Society of America 61 4 851–859 10.1785/BSSA0610040851 130174309 The earthquake was a result of strike-slip faulting along a NW-SE trending near vertical fault plane, as shown by the focal mechanism and the distribution of aftershocks.Foster A.N. Jackson J.A. 1998 Source parameters of large African earthquakes: implications for crustal rheology and regional kinematics Geophysical Journal International 134 2 422–448 10.1046/j.1365-246x.1998.00568.x 1998GeoJI.134..422F free Tectonic setting The Western Cape lies on the Cape Fold Belt, which is characterised by many thrust faults. Some of these thrust faults were reactivated during Cretaceous rifting as extensional faults, such as the Worcester Fault, which comes to the surface close to the epicentral area, but does not appear to be active. Earthquake The earthquake was estimated to have a magnitude of 6.3 L yes. The ISC-GEM catalogue records it as 6.3 w yes. The focal mechanism shows that the earthquake was a result of strike-slip faulting, either sinistral movement on a NW-SE trending fault or dextral movement on a NE-SW trending fault. As the zone of aftershocks was elongated in a NW-SE direction, the NW-SE plane is regarded as the fault responsible. There is no evidence of a surface fault trace and it has not been possible to tie the earthquake to movement on a known fault structure. However, faults of similar orientation are known from nearby areas. Aftershocks The main-shock was followed by a long series of aftershocks. The largest aftershock occurred nearly six months later on April 14, 1970, and had a magnitude of 5.7 w. Damage Damage was particularly severe in the towns of Ceres, Tulbagh, Wolseley and Prince Alfred Hamlet. There was also significant damage in Porterville and Worcester and the villages of Gouda, Saron and Hermon.Kijko A. Retief S.J.P. Graham G. 2002 Seismic Hazard and Risk Assessment for Tulbagh, South Africa: Part I – Assessment of Seismic Hazard https://www.researchgate.net/publication/225496673 Natural Hazards 26 2 175–201 10.1023/A:1015671813315 140686381 The earthquake severely affected Church Street in Tulbagh, which was renowned for its 18th to 20th-century buildings in Cape Dutch, Victorian and Edwardian styles. From the ashes of South Africa's worst earthquake rise the old buildings of Tulbagh http://www.theheritageportal.co.za/article/ashes-south-africas-worst-earthquake-rise-old-buildings-tulbagh The Heritage Portal https://web.archive.org/web/20190305151639/http://www.theheritageportal.co.za/article/ashes-south-africas-worst-earthquake-rise-old-buildings-tulbagh 2019-10-03 2019-03-05 Aftermath The buildings in Church Street were restored, initially by the National Committee for the Restoration of Historic Buildings in Tulbagh and its Environment, and later by the Tulbagh Valley Heritage Foundation. See also South Africa Earth sciences List of earthquakes in 1969 List of earthquakes in South Africa References Category:Earthquakes in South Africa Category:September 1969 in Africa Tulbagh Category:1969 in South Africa Category:Western Cape Category:Cape Winelands District Municipality Category:Strike-slip earthquakes