Seimic Sensors Orientation Using Earthquake and Noise Recordings

In this work we apply a new technique based on a complex linear least-squares method, to derive orientation of seismic sensors for two different acquisition setups: a borehole sensor array deployed in a gas field located in the Netherlands and a seismic array in Norway. Sensor alignment is performed using earthquake (both regional and teleseismic events) and low-frequency coherent noise recordings. Finding orientation of seismic sensors by complex linear least-squares approach has the advantage that we are dealing with a linear inverse problem. For this reason there are no complications with local minima and it is possible to add more independent data (other seismic events) to better constrain the solution of the inverse problem. Furthermore, our methods is faster than relative orientation methods based on waveform cross-correlation, and allows to estimate simultaneously all relative orientation angles of each sensors pair. An other advantage of our methods is that, unlike polarization analysis based methods, it can be applied to the full waveform and not only to highly linear polarized part of the waveform.