1. Seismic vault construction and challenges: HartRAO and Klerefontein
10th Inkaba yeAfrica/!Khure Africa (AEON) Conference/Workshop
Lord Milner Hotel, Matjiesfontein - Karoo
29 September – 3 October 2014
Seismic vault construction and challenges: HartRAO and Klerefontein
M. S. Rakgalakane1,2 , W. L. Combrinck2 ,C. J. S. Fourie1
1.Department of Environmental, Water and Earth Sciences, Tshwane University of Technology
2. Space Geodesy Programme, Hartebeesthoek Radio Astronomy Observatory

2. INTRODUCTION
Seismic vaults host instruments that pick up vibrations coming from the Earth’s crust
Selection of seismic vault sites should be isolated from any noise pollution
There should be access to the following onsite:
Bedrock
Security
Electricity
Internet
Each vault is to uphold rock mechanics and
be waterproofed

3. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Engineering vault design Excavation
The vault chamber consists of six (6) sections with access opening at roof slab
Bedrock found at 4 m below surface

4. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Rock test to determine breaking stress and strength

5. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Rock test to determine (S and P waves)
Rock sample
Thickness (m)
Time (µs)
Velocity (m/s) 1
0.027
50.6
533 2
0.023
35.9
640 3
0.024
49.9
480 4
0.022
64.9
338 5
0.016
32.3
495
Average velocity of S - waves =497.2 m/s
Rock sample
Thickness (m)
Time (µs)
Velocity (m/s) 1
0.027
17.7
1525 2
0.023
6.4
3593 3
0.024
14.4
1631 4
0.022 20
1100 5
0.016
15.6
1025
Average velocity of P-waves =1774.8m/s

6. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Rock test to determine density
Rock
Sample No
Mass in air
Mass + copper wire
Mass + copper in water
Density (g/cm3) 1
45.2
46.8
29.6
2.628 2
45.6 47
28.8
2.505 3
33.5
64.0
38.2
1.298 4
79.9
82.0
49.9
2.490 5
62.8
64.4
38.5
2.425 6 90
92.9 54
2.314 7
31.2
18.9
2.407 8
33.0
34.7 21
2.409 9
67.7
69.2
41.8
2.471 10
64.1
65.7
39.7
2.465
Average density of shale rock=2.341 g/cm3

7. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Construction of floor slab…

8. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Construction of reinforced pier …

9. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Assembling of chambers…

10. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Construction of vault…

11. SEISMIC VAULT CONSTRUCTION AT HARTRAO
End Product

12. SEISMIC VAULT CONSTRUCTION AT HARTRAO
Challenges…
Figure 1: Uneven surface
Figure 2: Delays
Figure 3: Leakage

13. PLANNING OF CONSTRUCTION AT KLEREFONTEIN
Chosen site
Picture taken by : Charles Coopley from SKA

14. Tsumeb
Polokwane
Lobatse
Witbank
HartRAO
Ladysmith
Boshof
Sutherland
NMMU
Courtesy of Dr Stoffel Fourie
Stellenbosch
Matjiesfontein
Current IMS Stations
Current Installations
Next Phase
Courtesy of picture to Dr Stoffel Fourie

15. CONCLUSION

16. ACKNOWLEDGMENTS I appreciate the support towards this project from:
Inkaba yeAfrica project
NRF
HartRAO
Prof Ludwig Combrinck and Dr Stoffel Fourie