Determining the orientations of ocean bottom seismometers using ambient noise correlation

The cross‐correlation of multicomponent ambient seismic noise can reveal both the velocity and polarization of surface waves propagating between pairs of stations. We explore this property to develop a novel method for determining the horizontal orientation of ocean bottom seismometers (OBS) by analyzing the polarization of Rayleigh waves retrieved from ambient noise cross‐correlation. We demonstrate that the sensor orientations can be estimated through maximizing the correlation between the radial‐vertical component and the phase‐shifted vertical‐vertical component of the empirical Green's tensor. We apply this new method to the ELSC (Eastern Lau Spreading Center) OBS experiment data set and illustrate its robustness by comparing the obtained orientations with results from a conventional method utilizing teleseismic P and Rayleigh wave polarizations. When applied to a large OBS array, the ambient noise method provides a larger number of orientation estimates and better azimuthal coverage than typically is possible with traditional methods. Key Points A new method for determining OBS orientation from ambient noise correlation Polarization of Rayleigh wave is retrieved by 3-component noise correlations Data quantity and azimuth coverage increase with number of sensors in the array