A Self-Noise Model for the German DEPAS OBS Pool

Simon C. Stähler et al.

Penerbit : Seismological Research Letters

Tahun : 2018

Ocean-bottom seismometers (OBSs) allow us to extend seismological research to the oceans to constrain offshore seismicity but also image the marine subsurface. A challenge is the high noise level on OBS records, which is created not only by bottom currents but also by the specific seismometer models used. We present a quantitative noise model for the LOBSTER OBS, which is the main instrument of DEPAS, currently the largest European OBS pool, stationed at Alfred-Wegener-Institut (AWI) Bremerhaven. Studying sensor noise in vault conditions and current sensitivity at an oceanographic measurement mast, we can show that the previously reported high noise level of the instrument is caused by the original sensor (Güralp CMG-40T-OBS). We also show that a strong signal that has been reported between 1 and 5 Hz can be attributed to headbuoy cable strumming. We provide a current-dependent quantitative noise model that can be used for experiment design in future deployments and show that the performance of the pool OBS can be improved at moderate cost by replacing the CMG-40T-OBS with a sensor of a proven noise floor below 10−8 nm=s 2, for example, a Trillium compact.

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