Acoustic attenuation in fluid-saturated porous cylinders at low frequencies

Dunn, Keh‐Jim

doi:10.1121/1.393232

Cited by 66 publications

(48 citation statements)

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“…Considering the axial seismic excitation, we assume that these specific modes are only extension and we neglect flexion and torsion (Dunn 1986). The goal of this analytical approach is to evaluate expected phase velocities of the different waves, in order to identify which waves are converted into seismoelectromagnetic fields.…”

Section: A N a Ly T I C A L A P P Roa C H F O R S E I S M O -E L E C mentioning

confidence: 99%

Evidence of the theoretically predicted seismo-magnetic conversion

Bordes

Jouniaux²,

Garambois

et al. 2008

Geophysical Journal International

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We acknowledge the Geophysical Journal International and the Association/Society and Blackwell Publishing. The definitive version is available at www.wileyinterscience.com. The reference is : Bordes, C., L. Jouniaux, S. Garambois, M. Dietrich, J.-P. Pozzi, and S. Gaffet, Evidence of the theoretically predicted seismo-magnetic conversion, G.J.I., 174, issue 2, 489-504, doi:10.1111/j.1365-246X.2008.03828.xInternational audienceSeismo-electromagnetic phenomena in porous media arise from seismic wave-induced fluid motion in the pore space, which perturbs the equilibrium of the electric double layer. This paper describes with details the original experimental apparatus built within the ultra-shielded chamber of the Low Noise Underground Laboratory of Rustrel (France). We measured seismo-magnetic conversions in moist sand using two induction magnetometers, and a pneumatic seismic source to generate the seismic wave propagation. We ensured to avoid the magnetometer vibrations, which could induce strong disturbances from induction origin. Interpretation of the data is improved by an analytical description of phase velocities for fast (P_f) and slow (P_s) longitudinal modes, transverse mode (S) as well as the extensional mode due to the cylindrical geometry of the sample. The purpose of this paper is to provide elements to measure correctly co seismic seismomagnetic fields and to specify their amplitude. The seismic arrivals recorded in the sample showing a 1200$-1300 m/s velocity have been associated to P and extensional waves. The measured seismo-magnetic arrivals show a velocity of about 800 m/s consistent with the calculated phase velocity of S waves. Therefore we show that the seismo-magnetic field is associated to the transverse part of the propagation, as theoretically predicted by Pride (1994), but never measured up to now. Moreover, the combined experimental and analytical approaches lead us to the conclusion that the measured seismo-magnetic field is probably about 0.35 nT for a 1 m/s2 seismic source acceleration (0.1 g)

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Section: A N a Ly T I C A L A P P Roa C H F O R S E I S M O -E L E C mentioning

confidence: 99%

Evidence of the theoretically predicted seismo-magnetic conversion

Bordes

Jouniaux²,

Garambois

et al. 2008

Geophysical Journal International

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“…This frequency is almost identical to Biot's characteristic frequency with the di!erence that it accounts for the tortuosity. It has been introduced by Dunn [20], with a qualitative justi"cation, in the study of the low frequency VIBRATIONS OF FLUID-SATURATED POROUS PLATE vibrational modes of a #uid-saturated sandstone cylinder. In some applications, can be chosen to coincide with a plate resonance (given by ) by an appropriate adjustment of the plate dimensions or the clamping conditions.…”

Section: Influence Of Porosity Tortuosity and Permeability On The Rementioning

confidence: 99%

Transverse Vibrations of a Thin Rectangular Porous Plate Saturated by a Fluid

Leclaire

Horoshenkov

Cummings

2001

Journal of Sound and Vibration

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A simple model of the transverse vibrations of a thin rectangular porous plate saturated by a #uid is proposed. The model is based on the classical theory of homogeneous plates and on Biot's stress}strain relations in an isotropic porous medium with a uniform porosity. Two coupled dynamic equations of equilibrium relating the plate de#ection and the #uid/solid relative displacement are found and their physical interpretation is given. The energy dissipation by viscous friction is included in the model. An approximate calculation of the natural frequencies of vibration is given for rigid plates with various boundary conditions at the edges. The in#uence of porosity, tortuosity and permeability on the resonances is studied and a condition of maximum damping involving these parameters is given.

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“…When analysing Spencer's experiments, White (1986) and Dunn (1986) demonstrated that the attenuation observed by Spencer was due to radial fluid flow caused by the open-pore boundary condition on the sample surface and, to some extent, due to anelasticity of the rock matrix. The same remarks can be attributed to the measurements of the extensional attenuation performed by Paffenholz and Burkhardt.…”

Section: Introductionmentioning

confidence: 99%