scholarly journals Review of Yan et al., “Antarctic ice sheet thickness estimation using the H/V spectral ratio method with single-station ambient noise”.

2017 ◽  
Author(s):  
Adam Booth
Keyword(s):  
Ambient Noise ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Antarctic Ice Sheet ◽  
Thickness Estimation ◽  
Single Station ◽  
Spectral Ratio Method

scholarly journals Antarctic ice sheet thickness estimation using the horizontal-to-vertical spectral ratio method with single-station seismic ambient noise

2018 ◽  
Vol 12 (2) ◽  
pp. 795-810 ◽  
Author(s):  
Peng Yan ◽  
Zhiwei Li ◽  
Fei Li ◽  
Yuande Yang ◽  
Weifeng Hao ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Spectral Ratio ◽  
Ice Thickness ◽  
Antarctic Ice Sheet ◽  
Seismic Stations ◽  
Thickness Estimation ◽  
Seismic Ambient Noise ◽  
The Antarctic

Abstract. We report on a successful application of the horizontal-to-vertical spectral ratio (H / V) method, generally used to investigate the subsurface velocity structures of the shallow crust, to estimate the Antarctic ice sheet thickness for the first time. Using three-component, five-day long, seismic ambient noise records gathered from more than 60 temporary seismic stations located on the Antarctic ice sheet, the ice thickness measured at each station has comparable accuracy to the Bedmap2 database. Preliminary analysis revealed that 60 out of 65 seismic stations on the ice sheet obtained clear peak frequencies (f0) related to the ice sheet thickness in the H / V spectrum. Thus, assuming that the isotropic ice layer lies atop a high velocity half-space bedrock, the ice sheet thickness can be calculated by a simple approximation formula. About half of the calculated ice sheet thicknesses were consistent with the Bedmap2 ice thickness values. To further improve the reliability of ice thickness measurements, two-type models were built to fit the observed H / V spectrum through non-linear inversion. The two-type models represent the isotropic structures of single- and two-layer ice sheets, and the latter depicts the non-uniform, layered characteristics of the ice sheet widely distributed in Antarctica. The inversion results suggest that the ice thicknesses derived from the two-layer ice models were in good concurrence with the Bedmap2 ice thickness database, and that ice thickness differences between the two were within 300 m at almost all stations. Our results support previous finding that the Antarctic ice sheet is stratified. Extensive data processing indicates that the time length of seismic ambient noise records can be shortened to two hours for reliable ice sheet thickness estimation using the H / V method. This study extends the application fields of the H / V method and provides an effective and independent way to measure ice sheet thickness in Antarctica.

scholarly journals Antarctic ice sheet thickness estimation using the H/V spectral ratio method with single-station seismic ambient noise

2017 ◽  
Author(s):  
Peng Yan ◽  
Zhiwei Li ◽  
Fei Li ◽  
Yuande Yang ◽  
Weifeng Hao ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Spectral Ratio ◽  
Ice Thickness ◽  
Antarctic Ice Sheet ◽  
Seismic Stations ◽  
Thickness Estimation ◽  
Seismic Ambient Noise ◽  
The Antarctic

Abstract. The horizontal-to-vertical spectral ratio (H/V) method implemented at single stations using seismic ambient noise waveforms is a fast, noninvasive, efficient method to investigate the subsurface velocity structures of the shallow crust. In this study, we report on a successful application of the H/V method to estimate the Antarctic ice sheet thickness for the first time. Using three-component, five-day long, seismic ambient noise records gathered from more than 60 temporary seismic stations located on the Antarctic ice sheet, the ice thickness at each station was reliably measured. Preliminary analysis revealed that 60 out of 65 seismic stations on the ice sheet obtained clear peak frequencies (f0) related to the ice sheet thickness in the H/V spectrum. Thus, assuming that the isotropic ice layer lies atop a high velocity half-space bedrock, the ice sheet thickness can be calculated by a simple approximation formula. About half of the calculated ice sheet thickness were consistent with the Bedmap2 ice thickness values. To further improve the reliability of ice thickness measurements, two-type models were built to fit the observed H/V spectrum through non-linear inversion. The two-type models represent the isotropic structures of single and two-layer ice sheet, and the latter depicts the non-uniform, layered characteristics of the ice sheet widely distributed in Antarctica. The inversion results suggest that the ice thicknesses derived from the two-layer ice models were highly consistent with the Bedmap2 ice thickness database, and their ice thickness differences were within 300 m at almost all stations. Our results support previous finding that the Antarctic ice sheet is stratified. Extensive data processing indicates that the time length of seismic ambient noise records can be shortened to 1–2 hours for reliable ice sheet thickness estimation using the H/V method. This study extends the application fields of the H/V method and provides a complementary and independent way to measure ice sheet thickness in Antarctica.

scholarly journals Event couple spectral ratio Q method for earthquake clusters: application to North-West Bohemia

2018 ◽  
Author(s):  
Marius Kriegerowski ◽  
Simone Cesca ◽  
Matthias Ohrnberger ◽  
Torsten Dahm ◽  
Frank Krüger
Keyword(s):  
Wave Attenuation ◽  
Attenuation Factor ◽  
Source Region ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Earthquake Swarms ◽  
North West ◽  
High Attenuation ◽  
West Bohemia ◽  
Spectral Ratio Method

Abstract. We develop an amplitude spectral ratio method for event couples from clustered earthquakes to estimate seismic wave attenuation (Q−1) in the source volume. The method allows to study attenuation within the source region of earthquake swarms or aftershocks at depth, independent of wave path and attenuation between source region and surface station. We exploit the high frequency slope of phase spectra using multitaper spectral estimates. The method is tested using simulated full wavefield seismograms affected by recorded noise and finite source rupture. The synthetic tests verify the approach and show that solutions are independent of focal mechanisms, but also show that seismic noise may broaden the scatter of results. We apply the event couple spectral ratio method to North-West Bohemia, Czech Republic, a region characterized by the persistent occurrence of earthquake swarms in a confined source region at mid-crustal depth. Our method indicates a strong anomaly of high attenuation in the source region of the swarm with an averaged attenuation factor of Qp 

Measuring the sediment thickness in urban areas using revised H/V spectral ratio method

2019 ◽  
Vol 260 ◽  
pp. 105223 ◽  
Author(s):  
Baoqing Tian ◽  
Yanan Du ◽  
Zhiwei You ◽  
Ruohan Zhang
Keyword(s):  
Urban Areas ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Sediment Thickness ◽  
Spectral Ratio Method

Damping-ratio measurements by the spectral-ratio method

2006 ◽  
Vol 43 (11) ◽  
pp. 1180-1194 ◽  
Author(s):  
Yu-Hsing Wang ◽  
Wai Man Yan ◽  
Kai Fung Lo
Keyword(s):  
Damping Ratio ◽  
Near Field ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Bender Elements ◽  
True Triaxial ◽  
Triaxial Apparatus ◽  
True Triaxial Apparatus ◽  
Spectral Ratio Method ◽  
Near Field Effect

In this paper, bender elements are used as sensors to measure the damping ratio of soil by the spectral-ratio method. The results of numerical and physical experiments suggest that adequate measurement precision can be achieved by reducing the two types of inherent biases arising from (i) the near-field effect and (ii) the different transfer functions of the two receiver bender elements. The first bias can be avoided by setting sensors to r1/λ ≥ 2.0 and r1/r2 ≥ 2.0, where r1 and r2 are the distances between the source and the first and second receivers, respectively; and λ is the wavelength. The second bias can be minimized by modifying the original spectral-ratio method to accommodate the self-healing technique. The damping ratios, measured by this modified method, obtained from the experiment conducted in a tailor-made, true-triaxial apparatus are very similar to those obtained from resonant column tests under the same state of stress.Key words: bender element, damping ratio, spectral-ratio method, near-field effect, true-triaxial apparatus.

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