Signals and noise in magnetotellurics

Conference · Sun Jun 01 04:00:00 EDT 1986

OSTI ID:5229069

Nichols, E; Morrison, H F; Clarke, J

Magnetotelluric noise properties were determined as a function of separation using an orthogonal array of stations. The simultaneous recording of high sensitivity biaxial tiltmeters along with the electric and magnetic fields allowed a measurement of the magnetic noise caused by sensor movement within the earth's static field. A point-by-point time domain linear least squares model was used allowing routine remote magnetic signal cancellation of typically 40 to 50 db. This method corrects for orientation and calibration errors of the magnetometers and removes tilt induced magnetic signals, thereby allowing accurate gradient magnetic field measurements on short baselines (less than 3 km). Microseismic activity in the low signal MT band, from 0.1 to 1 Hz, is demonstrated to bias the impedance estimate downward, even using the remote reference technique, due to correlated tilt motion. Tilt corrected expressions for both single site and remote reference MT impedance are formulated and compared to the standard remote reference expression. 3 refs., 4 figs. (DWL)

• Research Organization: Lawrence Berkeley Lab., CA (USA). Earth Sciences Div.
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5229069
• Report Number(s): LBL-21720; CONF-8510368-1; ON: DE87000111
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580203* -- Geophysics-- Geophysical Survey Methods-- (1980-1989)
ACOUSTIC MONITORING
ELECTRICAL SURVEYS
ELECTROMAGNETIC SURVEYS
GEOPHYSICAL SURVEYS
LEAST SQUARE FIT
MAGNETOMETERS
MAGNETOTELLURIC SURVEYS
MAXIMUM-LIKELIHOOD FIT
MEASURING INSTRUMENTS
MONITORING
NOISE
NUMERICAL SOLUTION
SURVEYS