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Elastic wave speeds and moduli in polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate

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dc.contributor.author Helgerud, M. B.
dc.contributor.author Waite, William F.
dc.contributor.author Kirby, S. H.
dc.contributor.author Nur, A.
dc.date.accessioned 2010-06-08T13:44:36Z
dc.date.available 2010-06-08T13:44:36Z
dc.date.issued 2009-02-27
dc.identifier.citation Journal of Geophysical Research 114 (2009): B02212 en_US
dc.identifier.uri http://hdl.handle.net/1912/3597
dc.description Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): B02212, doi:10.1029/2008JB006132. en_US
dc.description.abstract We used ultrasonic pulse transmission to measure compressional, P, and shear, S, wave speeds in laboratory-formed polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate. From the wave speed's linear dependence on temperature and pressure and from the sample's calculated density, we derived expressions for bulk, shear, and compressional wave moduli and Poisson's ratio from −20 to −5°C and 22.4 to 32.8 MPa for ice Ih, −20 to 15°C and 30.5 to 97.7 MPa for sI methane hydrate, and −20 to 10°C and 30.5 to 91.6 MPa for sII methane-ethane hydrate. All three materials had comparable P and S wave speeds and decreasing shear wave speeds with increasing applied pressure. Each material also showed evidence of rapid intergranular bonding, with a corresponding increase in wave speed, in response to pauses in sample deformation. There were also key differences. Resistance to uniaxial compaction, indicated by the pressure required to compact initially porous samples, was significantly lower for ice Ih than for either hydrate. The ice Ih shear modulus decreased with increasing pressure, in contrast to the increase measured in both hydrates. en_US
dc.description.sponsorship This work was supported by NSF grant OCE-97-10506, DOE grants DE-FG0386ER 13601 and DE-FG07-96ER 14723, DOE/LLNL contract W-7405-ENG-48, GRI grant 5094-210-3235- 1, NEDO, as well as by the U.S. Geological Survey’s Coastal and Marine Geology and Eastern Region Gas Hydrate Programs. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.relation.requires http://hdl.handle.net/1912/3599
dc.relation.uri http://dx.doi.org/10.1029/2008JB006132
dc.subject Wave speed en_US
dc.subject Elastic moduli en_US
dc.subject Gas hydrate en_US
dc.title Elastic wave speeds and moduli in polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate en_US
dc.type Article en_US
dc.identifier.doi 10.1029/2008JB006132


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