Controlled Source Audio MT

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Exploration Technique: Controlled Source Audio MT

Exploration Technique Information
Exploration Group: Geophysical Techniques
Exploration Sub Group: Electrical Techniques
Parent Exploration Technique: Magnetotelluric Techniques
Information Provided by Technique
Lithology: Rock composition, mineral and clay content
Stratigraphic/Structural: Detection of permeable pathways, fracture zones, faults
Hydrological: Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water
Thermal: Resistivity influenced by temperature
Cost Information
Low-End Estimate (USD): 1,866.44186,644 centUSD
1.866 kUSD
0.00187 MUSD
1.86644e-6 TUSD
/ mile
Median Estimate (USD): 11,696.631,169,663 centUSD
11.697 kUSD
0.0117 MUSD
1.169663e-5 TUSD
/ mile
High-End Estimate (USD): 25,000.002,500,000 centUSD
25 kUSD
0.025 MUSD
2.5e-5 TUSD
/ mile
Time Required
Low-End Estimate: 3.97 days0.0109 years
95.28 hours
0.567 weeks
0.13 months
/ 10 mile
Median Estimate: 11.64 days0.0319 years
279.36 hours
1.663 weeks
0.382 months
/ 10 mile
High-End Estimate: 28.12 days0.077 years
674.88 hours
4.017 weeks
0.924 months
/ 10 mile
Additional Info
Cost/Time Dependency: Location, Size, Resolution, Terrain, Weather
Controlled Source Audio MT:
Controlled Source Audio-Magnetotellurics (CSAMT) is an active source application of a magnetotelluric survey aimed at providing a more reliable signal and rapid acquisition time relative to a natural source MT measurement.
Other definitions:Wikipedia Reegle

Controlled-source audio-magnetotellurics (CSAMT) utilizes an active, artificial source to generate the signal for the MT measurement. The typical period range for a CSAMT survey is 10^-4 seconds to 8 seconds.[1]

CSAMT soundings image the apparent resistivity of the subsurface at shallower depths than broadband MT surveys, typically to 2-3 kilometers into the earth's crust.[2]
Use in Geothermal Exploration
See Electrical Techniques: Use in Geothermal Exploration

Field Procedures
The signal for a CSAMT survey is artificially generated through the installation of a long grounded dipole. This source dipole must be located at least four to five times the distance of the skin depth away from the recording stations in order to treat the electromagnetic fields as uniform MT fields for modeling purposes. The recording unit and transmitter are synchronized to apply a pre-programmed recording schedule which defines the time duration of the measurement and the frequencies to record.[1]

The survey layout and equipment for the MT stations is the same as for a MT survey. The only exceptions might be a smaller induction coils for the high-frequency magnetic measurements and shorter electrode lines, as well as more rapid data acquisition time.[1] Scalar CSAMT measures one component of the electrical field and the orthogonal component of the magnetic field.[2]
Environmental Mitigation Measures
CSAMT surveys are minimally invasive geophysical surveys. The fuel consumption for the transmitter and means of transport to the MT stations are the primary impacts.


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