Estimation of Seafloor Electromagnetic Receiver Orientation

If for different reasons the orientation of a seafloor EM instrument is unknown, it has to be estimated afterwards. Here we present a method to estimate the horizontal and vertical orientation of seafloor electromagnetic receivers. Three component magnetic recordings of the naturally occuring magnetotelluric field are utilized to find azimuth, tilt, and pitch angle relative to a given reference. Estimation of angles is controlled by a minimum difference criterion of time series segments. Precautionary measures are necessary to eliminate the subsurface response in the recordings of the EM field components. The simple geometry of the naturally occuring plane wave EM field allows us to quickly estimate the orientation of the instruments.