Preprints
https://doi.org/10.5194/tc-2023-19
https://doi.org/10.5194/tc-2023-19
24 Feb 2023
 | 24 Feb 2023
Status: this preprint is currently under review for the journal TC.

Seismic attenuation in Antarctic firn

Stefano Picotti, José M. Carcione, and Mauro Pavan

Abstract. We estimate the P- and S-wave seismic attenuation in polar firn from spectral analysis of diving-wave first-breaks of three-component active-source seismic observations carried out in 2010 on the Whillans Ice Stream (WIS), a fast-flowing ice stream in West Antarctica. The resulting quality factors are then successfully modeled using a rock-physics theory of wave propagation which combines White's mesoscopic attenuation theory of interlayer flow with that of Biot/squirt flow. The first theory describes an equivalent viscoelastic medium of a stack of two thin alternating porous layers of thickness much larger than the pore size but smaller than the wavelength. On the other hand, in the so-called Biot/squirt-flow model, there are two loss mechanisms, namely the Biot global-flow one and local flow from fluid-filled micro-cracks (or grain contacts) to the pore space and back, where the former is dominant over the latter. The fluid saturating the pores is assumed to be fluidized snow, which is defined as a mixture of snow particles and air, like powder, having zero rigidity modulus.

Stefano Picotti et al.

Status: open (until 14 Jun 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2023-19', Rolf Sidler, 05 Mar 2023 reply
    • AC1: 'Reply on RC1', Stefano Picotti, 15 Mar 2023 reply
  • RC2: 'Comment on tc-2023-19', Matthias Steiner, 11 May 2023 reply

Stefano Picotti et al.

Stefano Picotti et al.

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Short summary
A physical explanation of the seismic attenuation in polar firn is essential to obtain information about the deeper geological formations (e.g. AVO). In this work we estimated and modeled the P- and S-wave attenuation profiles in the firn of Whillans Ice Stream from spectral analysis of diving-wave first-breaks of three-component active-source seismic data. The model of wave propagation in firn combines White's mesoscopic attenuation theory of interlayer flow and that of Biot/squirt flow.