Page 36 - Summer2019
P. 36

Peculiar Acoustics of Rocks
It has also been suggested by Page et al. (2004) and many Acknowledgments
others that there may be disturbances within the quartz We gatefully acknowledge the sustained and continuous sup-
crystals themselves. Perhaps nonlinearity is a result of the port from the Oflice of Basic Energy Sciences, US Department
movement of crystalline lattice structures (i.e., dislocations) of Energy.
under an acoustic excitation. However, such physics at the
. . References
crystalline level do not appear to play a role. A set of experi-
mmt‘ “’h“° q““l'5‘afi° s'”5S'5”"‘i“ curves “'3” °b‘“jmd Adams. F. D., and Coker, E. G. (1905), An Investigation into the
5'L"1“1"3D9°“51Y with 1““t“’“‘5°3““ U13 m“5“1'9D18nt5 Elastic cansnmu nfRurks. Mm Bpmmlly with Reference In Cubic Com-
(Darling et al., 2004) shows that the average crystalline preuibility. Publication No. 46, Carnegie Institution of Washington,
behavior in a sandstone is linear (i.e.. each grain behaves w“‘h"‘5‘°“’DC' A A , _ _ _‘ I
, , , Becker, R. (1925). Elastic atreresect and plasticity. Zezfsclmjt/ur Physik 3,
35 3 P5595‘ hm‘ 5P“11E)- W511 '-h°“Sh ‘he 'm“'°5‘°P“ 135-213. hilps://doiorg/l n.1oo7rBFo132a3a4
stress-strain curves are quite nonlinear! It seems reason- Bittner, 1. A., and Popuvies, I. S. (2019). Direct imaging of moisture effects
able to conclude that it is the geometric structure of the entire il“1'l“E :10" Wham‘? D°“5Dl““Y- APPIW Physi“ M3975 114(1). 021901-
_ . . . . _ il(ps:// o|.org/ 10.1063/1.506390-1
°f"”'m_ted 3' '71" mam" ‘hm ” largely '“5P°"5'bl_ef"r ‘he ",0" Burley, 5., andworden, R. (Erl.s.). (2099). SamkinneDiugeneus:Recent11nd
lmeunty and not the crystals themselves. In addition, having A,mm,_ John Wu”, 5, Sam New Yuk
fluids present at the contact surfaces seems to be necessary Claytnr, K. E.. knby, I. R, and TenCate, I. A. (2009). limitations of Preisacb
as well. Researchers are actively seeking other experiments Thmri"-hEl35fiC 3k"=5¢J:‘» C"DJ§'“=fl€£-and dl1°i1“m=1“°*'Y-G¢°Ph75l°“l
to learn more about the processes at the grain scale and   Vow, S. C
13'8" [W915 Y€SP°n5ib1= 50' '-he b=h3V1°f 53°“ 3“ 1'°Ck5- (2004). Neutron diffraction study oftbe contribution of grain contacts
to nonlinear stress-strain behavior. Gmphysiml Research Letters 3105).
conclusions Elliilpsi//¢1ni.ogg/IlZ0.:;)1:/2004g.l.;I204:i(u  S K 2001 In“
In summary, there are three general classes of behavior  d::“(‘:ledaS'fi;;non HEX“ o‘mci(b'E(‘m§_)'H 
that have been observed in rocks: (1) classical nonlinearity; terization oinionysos marble. Intem1ztiovml]oumnlofSulitit andshudum
(2) hyflefgsjs; and (3) slow dynanlics There mg 3150 [hree JB(22-23), 4119-4145.hltps:l/doulryI0.ll]1615002077683-((I()l00252r3
important features in rocks that we think are the key con- M€K?V:nag}?'B"andSm,Zl"1f'D'[1974)'.MKhmimlhYmm'Smmd$m°w
, _ , _ stxaiuarnphtudesandseuxmieh'equenc|zs.PI1y:|:xaftI1eEurtl1andPhnzl1zr}I
“"b“‘°‘5 t0 the °bS°"’°d b9113"1°’i (1) $“"1'l°'E1'3“‘ 5°“‘3C‘ Interior: 3(3), 246450. bttps://dowryl\).l016/flU3l—92(ll(74)9U09l-O
dynamics; (2) geometrical arrangement of grains (e.g., how Meegan, G. D., It-., Iohnsun, P. A.. Guyer, R. A., and McCall, K. R.
“my an cemgmed and oriented and how much Pom space [1993):n1(£lhserva:ionsh£of nonlinelar elastic wave. behavior in s:nd~
there is between them); and (3) fluids that provide lubrica- /dm nigéfiricfl Sam” Dfmmnm 94(6)’ 33873391"
tion between grains, fluid-grain surface tension elfects, and page_ K_ L) pmfl-e,.,_ T“ Md_a5,.,_ 5_ )3__ Damng 1: Wu “,3 12,15“)
maybe even high-pressure chemistry at contact points. I. A. (2004). Local atomic structure of Fontaineblezu sandstone:
Evidence for an amm-prim phase? Geaphysiml Rlsearch Letter: 31(24).
. . . _ lItl'ps:/fd0iorg/10.1029/Z(J04GU)2lTl7
Mm?’ k°Y ‘l“°5'-‘°“5 “b°“‘ lb‘ “‘‘‘“5'-‘‘ b°h“"“” °f "’°k5 5”“ Pasqnallni. D., Heitmann, K.. TenCate, I. A., Habih. 5., Hjgdon, D., and
remain to be answered. What is the connection between the Iabnson, P. A. (2007). Nonequilibrium and nonlinear dynamics in Berea
proposed physics described in this article and the observed ind F01"-9i1“_l’l==“ Sand-“°“=53 10W'5“f1ifl E55139» 101"“! 0fG‘°P’1)’5““’
behavior? To further understanding, there is a great need for   017)-
m°f9V€¥V Small 56315 =XPmm¢fl‘-?- bk‘ *9 0'19 50116 l7YB1m1°‘ Propagation otlnlinitz-amplitude elastic pulse in abar ofBer=s sandstone:
and Popovics (2019). There is also a need for very detailed Adebiiledlook at the mechanisms ofclaxsi(zlnonl.inearity,hyste_resix,and
finite-element models with all the above physics embedded, “°““l““5b’5“m dY":"‘iC5'-l7'I’"'7‘“’ "fG‘”Ph}’5_f‘“1 R5‘f“"l'? 5°“ Em“
=5 now being done M15 Aims NW3“-1 L=b°r=t°rY» and .3.3.”.‘§.‘.”.f‘.“,°.ii“;°.°?;9‘7‘§5'./§.2;?Z‘§fi?;i3§.3i‘1';?’;3§f$?. pt... 
PEYMPS 3150 Wflfkiflg W11“ 13'8" “la” 11555915 FCPIESGDW fury/Noniimxtionz Irllmstm County Courthouse. National Parkszrvice,
tive models. The quest is for the simplest models that capture Washington, DC.
in mg imponmt {mum of the Peculiar behavim of a mck snmirar, s_ 2.. Lognnnne, e, Spohn, T., Eanerdt. w. in Breuer, D.,’ chris-
Ul _ el ch d 15 b d d_ d b tensem U., Dehanl. V., Dnileau, M4 Folknfil, W. Fuji, N.» and Garcia, R. F.
‘"“3‘ Y- 5“ m° '3 “'1 6 "5' '° F” ‘Ct an 9"" (2019). Pre-mission Insights on the interior otmars. Space Science Reviews
understand what goes on in the earth deep beneath us. 215(1). 3. imp;//dmnrg/io.1007/stizmua-0553.9
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