Estimating frequency-dependent attenuation quality factor values from prestack surface seismic data

Beckwith, James; Clark, Roger A.; Hodgson, Linda

doi:10.1190/geo2016-0169.1

“…Interpretations of "Vertical Seismic Profile" (VSP) data invoke fewer traveltime assumptions than for surface surveys; hence, properties can be more accurately defined (Gusmeroli et al, 2013). These properties can extend to velocity and velocity anisotropy (Diez et al, 2015), attenuation (Beckwith et al, 2017), and reflection coefficients (Lira et al, 2012). Furthermore, VSP surveys can recover englacial seismic properties even where there is no internal reflectivity (Gusmeroli et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Distributed Acoustic Sensing of Seismic Properties in a Borehole Drilled on a Fast‐Flowing Greenlandic Outlet Glacier

Booth

¹

,

Christoffersen

²

,

Schoonman

³

et al. 2020

Geophysical Research Letters

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Distributed Acoustic Sensing (DAS) is a new technology in which seismic energy is detected, at high spatial and temporal resolution, using the propagation of laser pulses in a fiber‐optic cable. We show analyses from the first glaciological borehole DAS deployment to measure the englacial and subglacial seismic properties of Store Glacier, a fast‐flowing outlet of the Greenland Ice Sheet. We record compressional and shear waves in 1,043 m‐deep vertical seismic profiles, sampled at 10 m vertical resolution, and detect a transition from isotropic to anisotropic ice at 84% of ice thickness, consistent with the Holocene‐Wisconsin transition. We identify subglacial reflections originating from the base of a 20 m‐thick layer of consolidated sediment and, from attenuation measurements, interpret temperate ice in the lowermost 100 m of the glacier. Our findings highlight the promising potential of DAS technology to constrain the seismic properties of glaciers and ice sheets.

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“…These methods can be further developed for frequency dependence of Q. For example, the spectral ratio method is incorporated with a frequency power law for Q to estimate the frequency variation of the quality factor [e.g., 14,17].…”

Section: Introductionmentioning

confidence: 99%

Nearly constant Q models of the generalized standard linear solid type and the corresponding wave equations

Hao,

Greenhalgh

2021

Preprint

0

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Time-domain seismic forward and inverse modeling for a dissipative medium is a vital research topic to investigate the attenuation structure of the Earth. Constant Q, also called frequency independence of the quality factor, is a common assumption for seismic Q inversion. We propose the first-and second-order nearly constant Q dissipative models of the generalized standard linear solid type, using a novel Q-independent weighting function approach. The two new models, which originate from the Kolsky model (a nearly constant Q model) and the Kjartansson model (an exactly constant Q model), result in the corresponding wave equations in differential form. Even for extremely strong attenuation (e.g., Q = 5), the quality factor and phase velocity for the two new models are close to those for the Kolsky and Kjartansson models, in a frequency range of interest. The wave equations for the two new models involve explicitly a specified Q parameter and have compact and simple forms. We provide a novel perspective on how to build a nearly constant Q dissipative model which is beneficial for time-domain large scale wavefield forward and inverse modeling. This perspective could also help obtain other dissipative models with similar advantages. We also discuss the extension beyond viscoacousticity and other related issues, for example, extending the two new models to viscoelastic anisotropy.

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“…Interpretations of "Vertical Seismic Profile" (VSP) data invoke fewer traveltime assumptions than for surface surveys; hence, properties can be more accurately defined (Gusmeroli et al, 2013). These properties can extend to velocity and velocity anisotropy (Diez et al, 2015), attenuation (Beckwith et al, 2017), and reflection coefficients (Lira et al, 2012). Furthermore, VSP surveys can recover englacial seismic properties even where there is no internal reflectivity (Gusmeroli et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Distributed Acoustic Sensing (DAS) of Seismic Properties in a Borehole drilled on a Fast-Flowing Greenlandic Outlet Glacier

Booth

¹

,

Christoffersen

²

,

Schoonman

³

et al. 2020

Preprint

View full text Add to dashboard Cite

Distributed Acoustic Sensing (DAS) is a new technology in which seismic energy is detected, at high spatial and temporal resolution, using the propagation of laser pulses in a fiber-optic cable. We show analyses from the first glaciological borehole DAS deployment to measure the englacial and subglacial seismic properties of Store Glacier, a fast-flowing outlet of the Greenland Ice Sheet. We record compressional and shear waves in 1,043 m-deep vertical seismic profiles, sampled at 10 m vertical resolution, and detect a transition from isotropic to anisotropic ice at 84% of ice thickness, consistent with the Holocene-Wisconsin transition. We identify subglacial reflections originating from the base of a 20 m-thick layer of consolidated sediment and, from attenuation measurements, interpret temperate ice in the lowermost 100 m of the glacier. Our findings highlight the promising potential of DAS technology to constrain the seismic properties of glaciers and ice sheets. Plain Language Summary Distributed Acoustic Sensing (DAS) is a new technology for seismicsurveying in which the transmission of light through fiber-optic cables is used to record seismic energy, with unprecedented spatial resolution compared to traditional techniques. Our paper presents data from the first borehole-glaciological deployment of DAS, in which fiber-optic cable was installed in a 1,043 m-deep vertical borehole on Store Glacier, a fast-flowing outlet of the Greenland Ice Sheet. The detailed seismic anatomy of the glacier that our survey provides-an independent measurement of the seismic response every 10 m-gives new insights about its internal flow regime and temperature and even allows us to detect layers of sediment underlying it. We predict that DAS surveying will play an increasingly large role in future glaciological investigations as the recognition of its promising potential grows.

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Estimating frequency-dependent attenuation quality factor values from prestack surface seismic data

Cited by 24 publications

References 31 publications

Distributed Acoustic Sensing of Seismic Properties in a Borehole Drilled on a Fast‐Flowing Greenlandic Outlet Glacier

Distributed Acoustic Sensing of Seismic Properties in a Borehole Drilled on a Fast‐Flowing Greenlandic Outlet Glacier

Nearly constant Q models of the generalized standard linear solid type and the corresponding wave equations

Distributed Acoustic Sensing (DAS) of Seismic Properties in a Borehole drilled on a Fast-Flowing Greenlandic Outlet Glacier

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