scholarly journals Characteristics of Low-frequency Ambient Seismic Noise in South Korea

2016 ◽  
Vol 19 (2) ◽  
pp. 67-75
Author(s):  
Iseul Park ◽  
Ki Young Kim ◽  
Joongmoo Byu
Keyword(s):  
South Korea ◽  
Seismic Noise ◽  
Low Frequency ◽  
Ambient Seismic Noise

Ambient seismic noise suppression in COST action G2Net

2020 ◽  
Author(s):  
Velimir Ilić ◽  
Alessandro Bertolini ◽  
Fabio Bonsignorio ◽  
Dario Jozinović ◽  
Tomasz Bulik ◽  
...  
Keyword(s):  
Machine Learning ◽  
Gravitational Waves ◽  
Seismic Noise ◽  
Noise Suppression ◽  
Real Life ◽  
Low Frequency ◽  
Ambient Seismic Noise ◽  
Cost Action ◽  
The Cost ◽  
Life Challenge

<p>The analysis of low-frequency gravitational waves (GW) data is a crucial mission of GW science and the performance of Earth-based GW detectors is largely influenced by ability of combating the low-frequency ambient seismic noise and other seismic influences. This tasks require multidisciplinary research in the fields of seismic sensing, signal processing, robotics, machine learning and mathematical modeling.<br><br>In practice, this kind of research is conducted by large teams of researchers with different expertise, so that project management emerges as an important real life challenge in the projects for acquisition, processing and interpretation of seismic data from GW detector site. A prominent example that successfully deals with this aspect could be observed in the COST Action G2Net (CA17137 - A network for Gravitational Waves, Geophysics and Machine Learning) and its seismic research group, which counts more than 30 members. </p><div>In this talk we will review the structure of the group, present the goals and recent activities of the group, and present new methods for combating the seismic influences at GW detector site that will be developed and applied within this collaboration.</div><div> <p> </p> <p>This publication is based upon work from CA17137 - A network for Gravitational Waves, Geophysics and Machine Learning, supported by COST (European Cooperation in Science and Technology).</p> </div>

Extracting subsurface information from ambient seismic noise — A case study from Germany

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. KS13-KS31 ◽  
Author(s):  
Alexander Goertz ◽  
Barbara Schechinger ◽  
Benjamin Witten ◽  
Matthias Koerbe ◽  
Paul Krajewski
Keyword(s):  
Seismic Noise ◽  
Body Wave ◽  
Source Region ◽  
Low Frequency ◽  
Spectral Ratio ◽  
Velocity Model ◽  
Body Waves ◽  
Seismic Survey ◽  
Ambient Seismic Noise ◽  
Oil Reservoir

We analyzed ambient seismic noise from a broadband passive seismic survey acquired in an urban area in Germany. Despite a high level of anthropogenic noise, we observe lateral variations in the quasi-stationary spectra that are of natural origin and indicative of the subsurface in the survey area. The best diagnostic is the ellipticity spectrum which is the spectral ratio of the vertical over the horizontal components. Deviations of the observed spectra from a pure Rayleigh-wave ellipticity allow an approximate separation of surface-wave from body-wave components in the analyzed frequency range, distinguishing shallow (upper tens of meters) from deeper (upper three kilometers) subsurface effects. We observe an increase of vertically polarized body waves between 1 and 4 Hz that is correlated to a subsurface structure that contains an oil reservoir at about 2-km depth. We located the source of the observed body wave microtremor in depth by applying an elastic wavefield back projection and imaging technique. The method includes normalization by the impulse response of the velocity model, effects of the receiver geometry, and lateral variation of incoherent noise. The source region of the low-frequency body wave microtremor is centered above the location of the oil reservoir. Two possible explanations for the deep microtremor are elastic body-wave scattering due to the impedance contrast of the structural trap, and viscoelastic scattering due to poroelastic effects in the partially saturated reservoir.

Very low frequency Ocean Bottom ambient seismic noise and coupling on the shallow continental shelf

1989 ◽  
Vol 11 (2) ◽  
pp. 129-152 ◽  
Author(s):  
Mark V. Trevorrow ◽  
Tokuo Yamamoto ◽  
Altan Turgut ◽  
Dean Goodman ◽  
Mohsen Badiey
Keyword(s):  
Continental Shelf ◽  
Seismic Noise ◽  
Low Frequency ◽  
Ambient Seismic Noise ◽  
Ocean Bottom ◽  
Very Low Frequency

High-frequency seismic noise as a function of depth

1991 ◽  
Vol 81 (4) ◽  
pp. 1101-1114
Author(s):  
Jerry A. Carter ◽  
Noel Barstow ◽  
Paul W. Pomeroy ◽  
Eric P. Chael ◽  
Patrick J. Leahy
Keyword(s):  
New York ◽  
High Frequency ◽  
Seismic Noise ◽  
Low Frequency ◽  
Time Variability ◽  
Orthogonal Components ◽  
The Difference ◽  
Frequency Coherence ◽  
Cultural Noise ◽  
Natural Wind

Abstract Evidence is presented supporting the view that high-frequency seismic noise decreases with increased depth. Noise amplitudes are higher near the free surface where surface-wave noise, cultural noise, and natural (wind-induced) noise predominate. Data were gathered at a hard-rock site in the northwestern Adirondack lowlands of northern New York. Between 15- and 40-Hz noise levels at this site are more than 10 dB less at 945-m depth than they are at the surface, and from 40 to 100 Hz the difference is more than 20 dB. In addition, time variability of the spectra is shown to be greater at the surface than at either 335- or 945-m depths. Part of the difference between the surface and subsurface noise variability may be related to wind-induced noise. Coherency measurements between orthogonal components of motion show high-frequency seismic noise is more highly organized at the surface than it is at depth. Coherency measurements between the same component of motion at different vertical offsets show a strong low-frequency coherence at least up to 945-m vertical offsets. As the vertical offset decreases, the frequency band of high coherence increases.

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