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Seafloor ground rotation observations; potential for improving signal-to-noise ratio on horizontal OBS components

Fabian Lindner, Joachim Wassermann, Mechita C. Schmidt-Aursch, Karl Ulrich Schreiber and Heiner Igel
Seafloor ground rotation observations; potential for improving signal-to-noise ratio on horizontal OBS components
Seismological Research Letters (November 2016) 88 (1): 32-38

Abstract

We report the first ground rotation observations on the seafloor from an experiment we carried out in the North Sea close to the island of Heligoland. A slightly modified commercial fiber optic gyroscope was mounted on an ocean-bottom seismometer (OBS) platform together with an intermediate-period seismometer. The system was lowered to the seafloor for 4 days. To investigate a potential tilt contamination of horizontal translational recordings, we calculate the coherence between the corresponding motion components (rotations around x axis and translations along y axis, and vice versa). We find very high correlations in the 5-13 s period interval, in which the correlation coefficient reaches 0.94 over 8.5 hrs. This clearly indicates that horizontal translational components are severely contaminated by rotations. We find that these rotational motions are caused by seafloor currents or deformation of the seafloor rather than by seismic waves. The ground rotation observations allow correcting for the cross-coupling effect, thereby decreasing the power spectral density up to 11 dB at 10 s period on horizontal OBS components. We discuss general requirements for broadband rotation sensors for OBS applications as well as for possible further applications.


ISSN: 0895-0695
EISSN: 1938-2057
Serial Title: Seismological Research Letters
Serial Volume: 88
Serial Issue: 1
Title: Seafloor ground rotation observations; potential for improving signal-to-noise ratio on horizontal OBS components
Affiliation: Ludwig-Maximilians-University of Munich, Department of Earth and Environmental Sciences, Munich, Germany
Pages: 32-38
Published: 20161102
Text Language: English
Publisher: Seismological Society of America, El Cerrito, CA, United States
References: 31
Accession Number: 2016-106792
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N54°08'60" - N54°08'60", E07°52'00" - E07°52'00"
Secondary Affiliation: Alfred Wegener Institute, DEU, GermanyTechnical University of Munich, DEU, Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201651
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