Abstract
A shallow seismic refraction survey and DC Resistivity Soundings were undertaken at southeastern margin of the Palaeo Ngami Lake to determine the structure and shallow stratigraphy of the lake; determine the amount of fault displacement at the border fault of the lake. The results of the seismic refraction survey indicate that the there is a low velocity zone (~500m/s) in the area which is thinner outside the lake (less than 10m) and much thicker toward the centre of the lake (more than 30m).This low velocity zone is underlain by a higher velocity (3125 m/s) layer. Augering results within the lake indicate that the low velocity zone consists of dry clays, diatomaceous earth/silts. The high velocity layer is believed to be made up of sandstone/siltstones. Fault displacement at the margin of the lake is about 21m of downthrow. Another downthrow (about 19m) occurs at a distance of about 1300m from the margin into the lake, thus resulting in a total throw of about 50m. The results of the DC resistivity sounding indicates that the low velocity zone within the lake is characterized by 3 distinct layers; the top layer which is less than 1 m thick, has a resistivity of about 1300 Ωm (dry hard clays), the second layer about 5 m thick and has a resistivity of 34 Ωm (diatomaceous earth) and the third layer has a resistivity of about 11 Ωm (whitish soft clays interlayered with silty units).
| Original language | English |
|---|---|
| Title of host publication | Environmental and Engineering Geophysical Society - 20th, SAGEEP 2007: Geophysical Investigation and Problem Solving for the Next Generation |
| Pages | 498-506 |
| Number of pages | 9 |
| Volume | 1 |
| Publication status | Published - 2007 |
| Event | 20th Symposium on the Application of Geophysics to Engineering and Environmental Problems: Geophysical Investigation and Problem Solving for the Next Generation, SAGEEP 2007 - Denver, CO, United States Duration: Apr 1 2007 → Apr 5 2007 |
Other
| Other | 20th Symposium on the Application of Geophysics to Engineering and Environmental Problems: Geophysical Investigation and Problem Solving for the Next Generation, SAGEEP 2007 |
|---|---|
| Country | United States |
| City | Denver, CO |
| Period | 4/1/07 → 4/5/07 |
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All Science Journal Classification (ASJC) codes
- Geophysics
- Geotechnical Engineering and Engineering Geology
- Environmental Engineering
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A geophysical investigation of the structural controls along the southern margin of Lake Ngami, northwestern Botswana using seismic refraction and DC resistivity. / Shemang, Elisha M.; Molwalefhe, Loago N.; Mosweu, Elvis.
Environmental and Engineering Geophysical Society - 20th, SAGEEP 2007: Geophysical Investigation and Problem Solving for the Next Generation. Vol. 1 2007. p. 498-506.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
TY - GEN
T1 - A geophysical investigation of the structural controls along the southern margin of Lake Ngami, northwestern Botswana using seismic refraction and DC resistivity
AU - Shemang, Elisha M.
AU - Molwalefhe, Loago N.
AU - Mosweu, Elvis
PY - 2007
Y1 - 2007
N2 - A shallow seismic refraction survey and DC Resistivity Soundings were undertaken at southeastern margin of the Palaeo Ngami Lake to determine the structure and shallow stratigraphy of the lake; determine the amount of fault displacement at the border fault of the lake. The results of the seismic refraction survey indicate that the there is a low velocity zone (~500m/s) in the area which is thinner outside the lake (less than 10m) and much thicker toward the centre of the lake (more than 30m).This low velocity zone is underlain by a higher velocity (3125 m/s) layer. Augering results within the lake indicate that the low velocity zone consists of dry clays, diatomaceous earth/silts. The high velocity layer is believed to be made up of sandstone/siltstones. Fault displacement at the margin of the lake is about 21m of downthrow. Another downthrow (about 19m) occurs at a distance of about 1300m from the margin into the lake, thus resulting in a total throw of about 50m. The results of the DC resistivity sounding indicates that the low velocity zone within the lake is characterized by 3 distinct layers; the top layer which is less than 1 m thick, has a resistivity of about 1300 Ωm (dry hard clays), the second layer about 5 m thick and has a resistivity of 34 Ωm (diatomaceous earth) and the third layer has a resistivity of about 11 Ωm (whitish soft clays interlayered with silty units).
AB - A shallow seismic refraction survey and DC Resistivity Soundings were undertaken at southeastern margin of the Palaeo Ngami Lake to determine the structure and shallow stratigraphy of the lake; determine the amount of fault displacement at the border fault of the lake. The results of the seismic refraction survey indicate that the there is a low velocity zone (~500m/s) in the area which is thinner outside the lake (less than 10m) and much thicker toward the centre of the lake (more than 30m).This low velocity zone is underlain by a higher velocity (3125 m/s) layer. Augering results within the lake indicate that the low velocity zone consists of dry clays, diatomaceous earth/silts. The high velocity layer is believed to be made up of sandstone/siltstones. Fault displacement at the margin of the lake is about 21m of downthrow. Another downthrow (about 19m) occurs at a distance of about 1300m from the margin into the lake, thus resulting in a total throw of about 50m. The results of the DC resistivity sounding indicates that the low velocity zone within the lake is characterized by 3 distinct layers; the top layer which is less than 1 m thick, has a resistivity of about 1300 Ωm (dry hard clays), the second layer about 5 m thick and has a resistivity of 34 Ωm (diatomaceous earth) and the third layer has a resistivity of about 11 Ωm (whitish soft clays interlayered with silty units).
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UR - http://www.scopus.com/inward/citedby.url?scp=84867274335&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84867274335
SN - 9781604239546
VL - 1
SP - 498
EP - 506
BT - Environmental and Engineering Geophysical Society - 20th, SAGEEP 2007: Geophysical Investigation and Problem Solving for the Next Generation
ER -