High resolution shallow reflection seismic data was acquired across a borehole located within an ... more High resolution shallow reflection seismic data was acquired across a borehole located within an abandoned coal mining site using three different types of geophones. The main objective of the study is to compare the vertical resolution of these geophones in order to choose the appropriate survey design for subsurface delineation of sinkholes or subsidence that might be present in the area. Two vertical geophones with resonant frequencies of 48 Hz and 100 Hz, and a horizontal geophone with resonant frequency of 14 Hz were employed in the investigation. Acquisition geometry was the same for all the geophones, and the energy source was provided by a sledge hammer hitting an aluminium plate. The data processing sequence was similar for all the geophones, and involves pre-stack, stacking, and post-stack stages. Signal attenuation with depth and dominant frequency vary among the geophones. The effect of multiples was noticed to be more severe in the data acquired with the 48 Hz vertical geophones, but less prominent in the 100 Hz vertical and the 14 Hz horizontal geophones. Post-stack, time-migrated sections generated for the three geophone types also show several reflections with depth for the 100 Hz vertical and 14 Hz horizontal geophones, as compared to the 48 Hz geophones.
The AfricaArray International Geophysics Field School is a three-week program designed to introdu... more The AfricaArray International Geophysics Field School is a three-week program designed to introduce the complete workflow of a geophysical project. In the first week, participants design a geophysical survey of relevance to a mine, water-resource investigation, or an archaeology study. The design of the course includes considerations of cost and safety and is presented in a competitive manner. The weeklong data-collection phase ensures that participants are familiar with operation of all equipment, including gravity, magnetics, DGPS, resistivity, EM31, EM34, and reflection and refraction seismology. Data are processed in the evening, and safety issues are reviewed the following morning. The final week is spent on campus, interpreting and integrating data to form a coherent model of the subsurface. The participants are selected from three cohorts: University of Witwatersrand geophysics students, SEG Foundation and UNESCO-sponsored African participants, and U. S.-sponsored undergradua...
High resolution shallow reflection seismic data was acquired across a borehole located within an ... more High resolution shallow reflection seismic data was acquired across a borehole located within an abandoned coal mining site using three different types of geophones. The main objective of the study is to compare the vertical resolution of these geophones in order to choose the appropriate survey design for subsurface delineation of sinkholes or subsidence that might be present in the area. Two vertical geophones with resonant frequencies of 48 Hz and 100 Hz, and a horizontal geophone with resonant frequency of 14 Hz were employed in the investigation. Acquisition geometry was the same for all the geophones, and the energy source was provided by a sledge hammer hitting an aluminium plate. The data processing sequence was similar for all the geophones, and involves pre-stack, stacking, and post-stack stages. Signal attenuation with depth and dominant frequency vary among the geophones. The effect of multiples was noticed to be more severe in the data acquired with the 48 Hz vertical geophones, but less prominent in the 100 Hz vertical and the 14 Hz horizontal geophones. Post-stack, time-migrated sections generated for the three geophone types also show several reflections with depth for the 100 Hz vertical and 14 Hz horizontal geophones, as compared to the 48 Hz geophones.
The AfricaArray International Geophysics Field School is a three-week program designed to introdu... more The AfricaArray International Geophysics Field School is a three-week program designed to introduce the complete workflow of a geophysical project. In the first week, participants design a geophysical survey of relevance to a mine, water-resource investigation, or an archaeology study. The design of the course includes considerations of cost and safety and is presented in a competitive manner. The weeklong data-collection phase ensures that participants are familiar with operation of all equipment, including gravity, magnetics, DGPS, resistivity, EM31, EM34, and reflection and refraction seismology. Data are processed in the evening, and safety issues are reviewed the following morning. The final week is spent on campus, interpreting and integrating data to form a coherent model of the subsurface. The participants are selected from three cohorts: University of Witwatersrand geophysics students, SEG Foundation and UNESCO-sponsored African participants, and U. S.-sponsored undergradua...
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