Characteristics and Spatial Variability of Wind Noise on Near‐Surface Broadband Seismometers

Dybing, Sydney N.; Ringler, Adam T.; Wilson, David C.; Anthony, Robert E.

doi:10.1785/0120180227

Cited by 42 publications

(38 citation statements)

References 38 publications

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“…Nenana basin (described next) has a strong influence on seismic noise, amplifying 0.1-0.7 Hz by 12-16 dB and 0.7-3 Hz by 17-30 dB. We hope that the empirical results presented here will help inform theoretical (Gimbert et al, 2014;Naderyan et al, 2016;Sorrells & Goforth, 1973;Tsai et al, 2012) and experimental (Anthony et al, 2018;Dybing et al, 2019;Hutt et al, 2017;Mucciarelli et al, 2005) efforts to investigate the effects of earth structure and environmental conditions on seismic noise. (PRA, 2017).…”

Section: Introductionmentioning

confidence: 80%

“…Haubrich and MacKenzie (1965) discovered that for frequencies <0.1 Hz the seismic displacement was "partially coherent" with pressure, and they attributed the effect "to elastic deformation of the ground by the atmosphere" (p. 1432). The degree of ground tilting caused by the atmosphere was shown to depend on the elastic properties near the surface (Dybing et al, 2019;Sorrells, 1971;Sorrells & Goforth, 1973;Sorrells et al, 1971;Ziolkowski, 1973). Nearly all stations on Earth, including within the Global Seismographic Network, record elevated levels of horizontal component noise relative to vertical component noise (H/Z ratio), which is suggestive of ground tilting.…”

Section: Introductionmentioning

confidence: 99%

“…Nearly all stations on Earth, including within the Global Seismographic Network, record elevated levels of horizontal component noise relative to vertical component noise (H/Z ratio), which is suggestive of ground tilting. Wind can also directly couple to the ground and generate high frequencies (>1 Hz) of ground motion (Dybing et al, 2019;Lott et al, 2017;Naderyan et al, 2016;Withers et al, 1996;Young et al, 1994). The effects of wind at low and high frequencies are reduced by installing seismometers deeper (Hutt et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Seismic Noise in Central Alaska and Influences From Rivers, Wind, and Sedimentary Basins

Smith

Tape

2019

JGR Solid Earth

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Ambient noise is useful for characterizing frequency-dependent noise levels and for assessing data quality for seismic stations. We use 4 years of ambient noise spectra from 16 stations in central Alaska to examine environmental and structural influences on seismic stations. The region contains a major river (Tanana River) that is ice covered for half the year and is underlain by a sedimentary basin (Nenana basin) that strongly influences the seismic wavefield. Nenana basin amplifies ambient seismic noise by 12-16 dB at 0.1-0.7 Hz and 17-30 dB at 0.7-3 Hz. A meteorological station and river gauge at Nenana provide environmental data for comparison with seismic stations. During the summer, the Tanana River produces noise levels elevated by 30-40 dB at frequencies near 10 Hz, as recorded by all five stations within 100 m of the main river channel. The Tanana River sediment is predominantly silt and sand in this region; therefore, we attribute the 10-Hz river signal to turbulence within the water and to unsteady shearing on the river bottom. The influence of wind is apparent on seismic noise at low (<0.05 Hz) frequencies, due to atmospheric-induced tilting, and at high (>2.0 Hz) frequencies, due to unsteady shearing and turbulence near the ground. Our empirical findings motivate future studies, such as how flow from air or water couples to the ground and how deep sedimentary basins influence the ambient noise wavefield. Our results have implications for seismic site selection, environmental monitoring, and detection and characterization of earthquakes.

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Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seismic Noise in Central Alaska and Influences From Rivers, Wind, and Sedimentary Basins

Smith

Tape

2019

JGR Solid Earth

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“…Journal of Geophysical Research: Solid Earth TANIMOTO AND LI Dybing et al (2019) recently reported a systematic study of wind-generated seismic noise and pointed out that both pressure fields and seismic-wave fields are quite heterogeneous. Those reports are generally true if one tries to understand a broad wind-speed range and also a broad pressure range.…”

Section: /2020jb019423mentioning

confidence: 99%

“…But their frequency range is mostly above 1 Hz and the results do not seem to apply to frequencies below 0.05 Hz. Dybing et al (2019) analyzed wind, pressure, and seismic data for a much broader frequency band and stressed that there are complex relations among them even at low frequencies. These conclusions are generally true if we do not pay attention to pressure amplitudes.…”

Section: Introductionmentioning

confidence: 99%

Nature of Low‐Frequency, Atmosphere‐Generated Seismic Noise

Tanimoto

2020

JGR Solid Earth

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Characteristics of atmosphere‐generated seismic noise below 0.05 Hz are investigated when surface pressure is large. In this paper, large pressure means pressure power spectral density exceeding 100 Pa2/Hz (at 0.01 Hz). We discuss three main points. The first point is existence of two frequency ranges that show high coherence between co‐located pressure and vertical seismic data. The lower frequency (LF) range is broad and its upper bound is about 0.002 Hz. The higher frequency (HF) range is bounded between about 0.01 and 0.05 Hz. Phase difference between pressure and vertical displacement is different for the two ranges. The LF range shows phase difference of zero, and the HF range shows phase difference of 180°. The second point is on the excitation mechanism in the HF range. Using theory and data, we show that seismic noise in the HF range is primarily excited by wind‐related pressure. When pressure is high, wind speeds become high, and wind directions become unidirectional. In such a case, a deterministic, moving pressure‐source by Sorrells (1971, https://doi.org/10.1111/j.1365-246X.1971.tb03383.x) captures the characteristics of data better than stochastic source models. The third point is on the cause of phase differences between the LF range and the HF range. The root cause is that, even after removing the instrument response, vertical seismic data contain effects from gravity and Earth rotation. Gravity effects become significant for frequencies below 0.005 Hz and create discrepancies between deconvolved vertical displacements and true vertical ground displacements. Phase‐difference results are naturally explained by it.

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Local Variations in Broadband Sensor Installations: Orientations, Sensitivities, and Noise Levels

Ringler

Anthony

2021

Pure Appl. Geophys.

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As seismologists continue to place more stringent demands on data quality, accurately described metadata are becoming increasingly important. In order to better constrain the orientation and sensitivities of seismometers deployed in U.S. Geological Survey networks, the Albuquerque Seismological Laboratory (ASL) has recently begun identifying true north with a fiber optic gyroscope (FOG) and has developed methodologies to constrain mid-band, vertical component sensitivity levels to less than 1% in a controlled environment. However, questions remain regarding the accuracy of this new alignment technique as well as if instrument sensitivities and background noise levels are stable when the seismometers are installed in different environmental settings. In this study, we examine the stability and repeatability of these parameters by reinstalling two high-quality broadband seismometers (Streckeisen STS-2.5 and Nanometrics T-360 Global Seismographic Network (GSN) version) at different locations around the ASL and comparing them to each other and a reference STS-6 seismometer that stayed stationary for the duration of the experiment. We find that even in different environmental conditions, the sensitivities of the two broadband seismometers stayed stable to within 0.1% and that orientations attained using the FOG are generally accurate to within a degree. However, one install was off by 5° due to a mistake made by the installation team. These results indicate that while technology and methodologies are now in place to calibrate and orient a seismometer to within 1°, human error both during the installation and while producing the metadata is often a limiting factor. Finally, we find that background noise levels at short periods (0.1–1 s) become noisier when the sensors are emplaced in unconsolidated materials, whereas the noise levels at long periods (30–100 s) are not sensitive to local geological structure on the vertical components.

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Characteristics and Spatial Variability of Wind Noise on Near‐Surface Broadband Seismometers

Cited by 42 publications

References 38 publications

Seismic Noise in Central Alaska and Influences From Rivers, Wind, and Sedimentary Basins

Seismic Noise in Central Alaska and Influences From Rivers, Wind, and Sedimentary Basins

Nature of Low‐Frequency, Atmosphere‐Generated Seismic Noise

Local Variations in Broadband Sensor Installations: Orientations, Sensitivities, and Noise Levels

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