| Event | Mw | Reference | Type of Study | Depth (km) | Remarks |
|---|---|---|---|---|---|
| 29 September 1969 Ceres mainshock | 6.2 | Green and Bloch (1971) | Aftershock locations from temporary local network | <9, possibly <6.5 | Maximum aftershock depth of 9 km; most aftershocks prior to 14 April 1970 event shallower than 6.5 km. Close-to-surface events were concentrated in the Ceres region, with events deeper than 6.5 km only occurring at distances greater than 17 km from Ceres |
| Shudofsky (1985) | Rayleigh-wave inversion and body-wave modeling | 30 | Focal depth from minimizing residuals between observed and predicted waveforms | ||
| Wagner and Langston (1988) | Waveform inversion and waveform fitting of digitized long-period WWSSN data | 4 | Use both P and SH waves to obtain focal solution | ||
| Foster and Jackson (1998) | Waveform inversion and waveform fitting of digitized WWSSN data | 5 | Use both P and SH waves to obtain focal solution | ||
| D. Storchák (e-mail comm., 2009) | Reanalysis of teleseismic ISC data | ~10 | Could not determine freely varying depth, optimal fixed-depth results for 10 km | ||
| Krüger and Scherbaum (2014) | Moment tensor solution using digitized WWSSN records | <20, centroid depth 15 | Authors note that the absence of depth phases on seismograms is indicative of shallow source. Use both P and SH waves to obtain focal solution. Depth depends on constraints imposed: 15 km is the depth for the shear-constrained double-couple solution | ||
| 14 April 1970 Ceres aftershock | 5.8 | Green and Bloch (1971) | Aftershock locations from temporary local network | <9 | Maximum aftershock depth of 9 km |
| Shudofsky (1985) | Rayleigh-wave inversion and body-wave modeling | 10 | Focal depth from minimizing residuals between observed and predicted waveforms | ||
| 1 July 1976 Koffiefontein | 5.8 | Shudofsky (1985) | Rayleigh-wave inversion and body-wave modeling | 6 | Focal depth from minimizing residuals between observed and predicted waveforms |
| Jensen (1991) | Body-wave inversion of long-period WWSSN data | 5.5 | Use both P and SH waves to obtain focal solution | ||
| D. Storchák (e-mail comm., 2009) | Reanalysis of teleseismic ISC data | 7–11 | Original ISC depth 28 km | ||
| 5 October 1986 Matatiele | 5.3 | Dziewonski et al. (1987) | Harvard centroid moment tensor solution | 15 | Default depth value for shallow earthquakes, probably fixed |
| EHB Bulletin | Reanalysis of ISC data | 11.7 ± 0.7 | Slight increase of the error ellipse compared to the ISC fixed-depth solution | ||
| 29 September 1989 SA-Lesotho border | 5.0 | ISC Bulletin | Routine location | 6.8 ± 22.7 | Large error indicative of poor constraints |
| EHB Bulletin | Reanalysis of ISC data | 7.7 | Error unspecified, slight increase of error ellipse with respect to ISC | ||
| 4 February 1999 Fauresmith | 3.8 | Brandt and Saunders (2011) | Regional moment tensor solution using SASE temporary array data | 11 | Event in Koffiefontein region (see 1 July 1976 event) |
| 18 December 2011 Augrabies | 4.3 | USGS-NEIC | USGS-NEIC rapid moment tensor solution | 10 | Default depth value for shallow earthquakes, probably fixed |
ISC, International Seismological Centre; EHB, Engdahl–van der Hilst–Buland; SASE, South African Seismic Experiment; USGS-NEIC, U.S. Geological Survey–National Earthquake Information Center.
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