On the Systematic Long-Period Noise Reduction on Ocean Floor Broadband Seismic Sensors Collocated with Differential Pressure Gauges

Taira, T.; Zheng, Zhao; Romanowicz, Barbara

doi:10.1785/0120130015

Cited by 7 publications

(9 citation statements)

References 54 publications

(59 reference statements)

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“…This behavior is also observed on the ocean floor for ocean-bottom station (OBS) data at Monterey ocean-bottom broadband observatory, and it is associated with infragravity waves (Taira et al, 2014). Because noise levels for periods within 30-50 s are critical (e.g., for surface-wave studies), Taira et al (2014) implemented a systematic long-period noise reduction calculation. Sea currents are another important source of noise at low frequency (< 0:1 Hz), which particularly affects the horizontal components, but also the vertical (due to tilting of the sensor).…”

Section: Discussionmentioning

confidence: 91%

Seafloor Seismic Noise at Central Eastern Mediterranean Sites

Monna

Frugoni

et al. 2014

Seismological Research Letters

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Section: Discussionmentioning

confidence: 91%

Seafloor Seismic Noise at Central Eastern Mediterranean Sites

Monna

Frugoni

et al. 2014

Seismological Research Letters

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“…We analyzed discreet 1‐hr segments of 1 sample per second continuous data. We first removed the tilt‐induced noise from the vertical acceleration data, a process which has been shown to improve the long‐period (<10 s) signal by 20 dB or more (e.g., Crawford et al, ; Crawford & Webb, ) and is now regularly applied to free‐fall OBS data (e.g., Dolenc et al, ; Taira et al, ). We specifically followed the method of Bell, Forsyth, and Ruan (), whereby the angle and direction of tilt are also found.…”

Section: Datamentioning

confidence: 99%

Seismic Structure of Marine Sediments and Upper Oceanic Crust Surrounding Hawaii

Doran

Laske

2019

JGR Solid Earth

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We present models of compressional and shear velocity structure of the oceanic sediments and upper crust surrounding the Hawaiian islands. The models were derived from analysis of seafloor compliance data and measurements of Ps converted phases originating at the sediment‐bedrock interface. These data were estimated from continuous broadband ocean bottom seismometer acceleration and pressure records collected during the Plume‐Lithosphere Undersea Mantle Experiment, an amphibious array of wideband and broadband instruments with an aperture of over 1,000 km. Our images result from a joint inversion of compliance and Ps delay data using a nonlinear inversion scheme whereby deviation from a priori constraints is minimized. In our final model, sediment thickness increases from 50 m at distal sites to over 1.5 km immediately adjacent to the islands. The sedimentary shear velocity profiles exhibit large regional variations. While sedimentary structure accounts for the majority of the compliance signal, we infer variations in shear velocity in the uppermost bedrock on the order of ±5%. We also require relatively high values of Poisson's ratio in the uppermost crust. Lower crustal velocities are generally seen to the north and west of the islands but do not appear well correlated with the Hawaiian Swell bathymetry. A region of strong low velocity anomalies to the northeast of Hawaii may be associated with the Molokai fracture zone.

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“…The objective of this research is to lower the noise level on vertical broadband OBS data and to identify the permanent normal modes of the Earth during periods of seismic quiescence. Although several authors were able to reduce low-frequency noise (Crawford & Webb, 2000;Dahm et al, 2006;Dolenc et al, 2007;Stutzmann et al, 2001;Taira et al, 2014), the hum remains challenging to observe. With our proposed noise reduction methods, we improve the data quality of broadband OBS so that the data become useful for a (Nishida et al, 2009, Haned et al, 2015.…”

Section: Introductionmentioning

confidence: 99%

First Observation of the Earth's Permanent Free Oscillations on Ocean Bottom Seismometers

Deen

Wielandt

Stutzmann

et al. 2017

Geophysical Research Letters

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The Earth's hum is the permanent free oscillations of the Earth recorded in the absence of earthquakes, at periods above 30 s. We present the first observations of its fundamental spheroidal eigenmodes on broadband ocean bottom seismometers (OBSs) in the Indian Ocean. At the ocean bottom, the effects of ocean infragravity waves (compliance) and seafloor currents (tilt) overshadow the hum. In our experiment, data are also affected by electronic glitches. We remove these signals from the seismic trace by subtracting average glitch signals; performing a linear regression; and using frequency-dependent response functions between pressure, horizontal, and vertical seismic components. This reduces the long period noise on the OBS to the level of a good land station. Finally, by windowing the autocorrelation to include only the direct arrival, the first and second orbits around the Earth, and by calculating its Fourier transform, we clearly observe the eigenmodes at the ocean bottom.

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On the Systematic Long-Period Noise Reduction on Ocean Floor Broadband Seismic Sensors Collocated with Differential Pressure Gauges

Cited by 7 publications

References 54 publications

Seafloor Seismic Noise at Central Eastern Mediterranean Sites

Seafloor Seismic Noise at Central Eastern Mediterranean Sites

Seismic Structure of Marine Sediments and Upper Oceanic Crust Surrounding Hawaii

First Observation of the Earth's Permanent Free Oscillations on Ocean Bottom Seismometers

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