Determining the orientations of ocean bottom seismometers using virtual sources

摘要

We present a new method for determining the horizontal orientation of ocean bottom seismometers (OBS) using the polarization of virtual Rayleigh waves retrieved from ambient noise cross-correlation. We demonstrate that the sensor orientation angle can be estimated through maximizing the correlation between the radial-vertical component and the Hilbert transformed vertical-vertical component of the empirical Greens tensor. We apply this method to L-SCAN OBS array data collected from the Eastern Lau Spreading Center, and illustrate its robustness by comparing the obtained orientations with results from a conventional method utilizing teleseismic P and Rayleigh wave polarizations. The advantage of the ambient noise method lies in the large number of inter-station ray paths and excellent azimuthal coverage for large OBS arrays. Potential applications include continuous monitoring of sensor orientations during time-lapse survays.