The CGS is developing a microzonation model for the City of Johannesburg
The CGS is developing a microzonation model for the City of Johannesburg, including those areas triggered by the abandoned and flooding mines. The objective of this model is to assist the mitigation of possible earthquake damages. The microzonation is a process where seismic hazards are identified at different locations within a geographical area and is essential for identifying potential seismic “hotspots”, which could affect critical structures, for example, bridges, elevated highways, subways, sky trains, dam sites (including tailings dams from the mines), and many more.
Quite a number of large cities around the world, including those in regions of low to moderate natural seismicity, such as South Africa, have put some effort into developing microzonation models for better understanding of the earthquake hazards within major cities. The project is on schedule with the first few tasks being completed within the first year.
These tasks include:
- Geological Setting Investigations,
- Preparation of the PSHA inputs,
- PSHA Calculations & Post processing to prepare Response Spectrum,
- Collection and analysis of borehole data, and
- Field Measurements to obtain shear wave velocity profiles and ambient noise vibrations