Signals and noise in magnetotellurics

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