Anisotropic attenuation in rocks: Theory, modelling and lab measurements

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985530%3A_____%2F17%3A00473593" target="_blank" >RIV/67985530:_____/17:00473593 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/67985831:_____/17:00473593

Výsledek na webu

<a href="http://dx.doi.org/10.1093/gji/ggw476" target="_blank" >http://dx.doi.org/10.1093/gji/ggw476</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/gji/ggw476" target="_blank" >10.1093/gji/ggw476</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Anisotropic attenuation in rocks: Theory, modelling and lab measurements

Popis výsledku v původním jazyce

Anisotropic attenuation affects seismic observations and complicates their interpretations. Its accurate determination is, however, difficult and needs extensive measurements of wavefields in many directions. So far, the traveltime and amplitude decay of waves are usually measured along a sparse grid of propagation directions, and methods for inverting for anisotropic attenuation are not fully developed. In this paper, we present theory allowing a description and parametrization of general triclinic anisotropic attenuation. We focus on a correct recalculation of ray quantities usually measured in lab to phase quantities needed in the inversion. We develop and numerically test an iterative inversion scheme for determining the parameters of anisotropic attenuation. We present a lab facility that allows for measuring anisotropic attenuation using the P-wave ultrasonic sounding of spherical samples in 132 directions distributed regularly over the sphere. The applicability of the proposed inversion method and the performance of the experimental setup are exemplified by determining triclinic anisotropic attenuation of the serpentinite rock from Val Malenco, Northern Italy. The ray velocity and ray attenuation were measured on a spherical sample of the rock with diameter of 45.5 mm at the room temperature and under two pressure levels: 0.1 and 20 MPa. The measurements confirmed that anisotropic attenuation is remarkably sensitive to confining pressure. Since cracks are closing with increasing pressure, attenuation decreases. However, changes in pressure can also induce changes in the directional variation of attenuation and rotation of anisotropy axes. The obtained results for the serpentinite rock sample are unique because they represent the first accurately determined triclinic anisotropic attenuation from lab measurements.

Název v anglickém jazyce

Anisotropic attenuation in rocks: Theory, modelling and lab measurements

Popis výsledku anglicky

Anisotropic attenuation affects seismic observations and complicates their interpretations. Its accurate determination is, however, difficult and needs extensive measurements of wavefields in many directions. So far, the traveltime and amplitude decay of waves are usually measured along a sparse grid of propagation directions, and methods for inverting for anisotropic attenuation are not fully developed. In this paper, we present theory allowing a description and parametrization of general triclinic anisotropic attenuation. We focus on a correct recalculation of ray quantities usually measured in lab to phase quantities needed in the inversion. We develop and numerically test an iterative inversion scheme for determining the parameters of anisotropic attenuation. We present a lab facility that allows for measuring anisotropic attenuation using the P-wave ultrasonic sounding of spherical samples in 132 directions distributed regularly over the sphere. The applicability of the proposed inversion method and the performance of the experimental setup are exemplified by determining triclinic anisotropic attenuation of the serpentinite rock from Val Malenco, Northern Italy. The ray velocity and ray attenuation were measured on a spherical sample of the rock with diameter of 45.5 mm at the room temperature and under two pressure levels: 0.1 and 20 MPa. The measurements confirmed that anisotropic attenuation is remarkably sensitive to confining pressure. Since cracks are closing with increasing pressure, attenuation decreases. However, changes in pressure can also induce changes in the directional variation of attenuation and rotation of anisotropy axes. The obtained results for the serpentinite rock sample are unique because they represent the first accurately determined triclinic anisotropic attenuation from lab measurements.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10507 - Volcanology

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Geophysical Journal International

ISSN

0956-540X

e-ISSN

—

Svazek periodika

208

Číslo periodika v rámci svazku

3

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

16

Strana od-do

1724-1739

Kód UT WoS článku

000396818900033

EID výsledku v databázi Scopus

2-s2.0-85014385222