Land Magnetometer Training Course
• Magnetic Theory ½ day• Hardware (G858/AP) ¼ day• Software (MagMap / MagPick) ¼ day• Hardware setup (858 and GPS) ½ day• Survey ½ day• Processing ½ day• Review ½ day
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Geometrics, Inc.Premier Manufacturer of Land Magnetometers
GEOMETRICS MAGNETOMETERS-tools for exploration
Applications:• Map Geology for Mining, Oil/Gas Exploration
• Environmental Survey for Tanks, Barrels
• Locate Utilities, Pipelines
• Military Uses, UXO-EOD, De-mining
• Archaeology
• Used in Land-Marine-Airborne Surveys
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GEOMETRICS: a 30-year history of building magnetometers
• 1969: G-801 & G-803 marine and airborne proton magnetometers• 1971: G-806 land and marine proton magnetometer• 1973: G-816 portable proton magnetometer• 1977: G-826 portable digital magnetometer• 1981: G-856 portable memory magnetometer• 1983: G-811 marine magnetometer• 1991: G-822L military magnetometer• 1992: G-825 military diver-held magnetometer• 1992: G-822A airborne cesium magnetometer• 1995: G-858 portable cesium magnetometer• 1996: G-880 marine cesium magnetometer• 1997: G-823A airborne cesium magnetometer with counter• 1998: G-881 marine light-weight cesium magnetometer• 2003: G-882 marine cesium magnetometer • 2005: G-859 cesium mining magnetometer• 2009: UAV, AUV testing• 2013: G-860 land cesium magnetometer• 2014: G-862RBS cesium base station
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Magnetometer Configurations
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UXO Magnetometer Configurations
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Sensor Noise – Spin analysis
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Sensor Noise – Tumble Analysis
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Sensor Noise – Various Motions
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Earth’s Magnetic Field Diagram
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Earth’s Magnetic Field – Solar effectsEarth’s Magnetic Field: detection of magnetic anomalies
• Earth’s dipole magnetic field is perturbed by relatively localized contrasts in magnetization.
• Magnetization contrasts are caused by ferrous debris, vessels, pipelines, communication cables, magnetic minerals (predominantly magnetite).
• With magnetometers, one can measure the total field to detect the magnetic anomalies associated with contrasts.
• Earth’s dipole (N-S) magnetic field is produced by internal iron core dynamo effect. Charged particles from the sun cause a bow shock wave in the magnetosphere which leads to Diurnal Variations
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Earth’s Total Magnetic Field
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Earth’s Magnetic Inclination
Diurnal Variations
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Optional Diurnal / Base Station Monitor
• Use either G-858 or G-856 Magnetometers
• Monitor Magnetic Diurnal Variations
• Magnetometer in fixed location
• Synchronized clocks
• 1-30 second sample rate
• Use for correction of survey data
• Produce more accurate magnetic maps
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Sensor Dead Zone Diagram
Sensor Diagrams - CSAZ
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Sensor Dead Zone – 0 Degree Tilt
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Sensor Dead Zone – 45 Degree Tilt
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Results of Survey profile width
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Anomaly patterns as a result of Inclination
Anomaly width versus depth
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Depth estimate
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Nomogram
Anomalies of common objects
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Vertical Gradient Applications
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Wearing the G-858
Gradiometer Transverse Layout
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WITH agGPS-114/132 STEERINGG-858 CESIUM GRADIOMETER
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Standard Survey Acquisition
Swath Spacing
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GPS Differential Corrections
• Coast Guard Beacon
• OmniStar (On shore only without special license)
• Racal (On shore only without special license)
• RTCM
• RTK
• Known Antenna and Satellite positions and frequencies
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Data Processing Software – Magmap 2000
Software capabilities
• Import G-858 magnetometer (1 or 2 sensors)
• Convert GPS Lat / Long to UTM XY coordinates
• Correct for GPS offset from Magnetometer sensor
• Perform Spike filtering
• Import G-858 or G-856 base station data
• Merge Base Station data with survey Data
• Export in Surfer or Geosoft format
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MagMap 2000 Destripping tool
Surfer Software Capabilities
• Windows based program for professional displays
• Grid and contour G-858 data
• Display sample locations on contour map
• Various types of displays for interpretation
• Export Windows Metafile and ASCII grid files for MagAID
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Surfer Displays – Ft. Ross
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Stanford Base Map
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Surfer 3 dimensional display
Stanford shaded relief
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Stanford Magnetic Contour Map
MagPick – Filtering theory
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RAW DATA
MANUAL SMOOTHING
3 POINT RUNNING AVERAGE
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