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Erschienen in:
2020 | OriginalPaper | Buchkapitel
12. Passive Seismic Survey of Sediment Thickness, Dasht-e-Nawar Basin, Eastern Afghanistan
verfasst von : Thomas J. Mack
Erschienen in: Military Geoscience
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Abstract
Exploration of water resources is needed for public supply and mineral resources development in Afghanistan. Remotely sensed data are useful for identifying the general nature of surface sediments; however, hazardous “boots on the ground” geophysics or drilling programs are needed to quantify the thickness of sediments. The Dasht-e-Nawar Basin, in east-central Afghanistan, contains a 400 km2 playa that includes evaporative mineral deposits, particularly lithium. In 2014, the USGS compared the results of a passive seismic survey of sediment thickness to the results of an independently conducted gravity survey of the basin.
Each passive seismic measurement required less than 30 minutes by one person utilizing ambient noise without external sound sources or sensor arrays. The gravity survey was conducted during a period of 3 weeks by an experienced field crew; required a detailed, centimeter-scale land elevation survey; and required laboratory analyses of sediment and rock densities to interpret the gravity data. In contrast, the passive seismic survey was collected by two inexperienced operators over a period of 8 days and required no additional data to interpret. Although the quality of the seismic survey was affected by strong afternoon winds and by the inexperience of the field operators, the results were fairly comparable to the gravity survey. Similar sediment thicknesses were identified by both surveys in the basin with an estimated maximum thickness of approximately 247 m. Although this method will not be effective in all geologic settings, it required substantially less effort than would be required by other geophysical surveys.