J. Jpn. Soc. Soil Phys.
῍
No. +*2, p. ,3-0 ,**2 CSMT ´ µ¶*

Application of the High-frequency CSMT Method to Surveys
in Shallow Subsurface Regions
Shun HANDA** Faculty of Agricultural Science, Saga University, Honjo machi +, Saga, 2.*῏2/*,, JapanAbstract
The surveys using the high-frequency CSMT system were carried out to make clear the electrical conductivity structures in the landslide area in Izumi and in the test-ﬁeld of Shirasu banks
in Satuma-sendai.
Although the survey in Izumi was conducted along a short line in a narrow ﬂat area, relatively
good data were obtained because of the short span of electrodes in this system.

The ,-D re-sistivity model indicates that a high-conductive layer possibly highly satisﬁed with water lies justupon impermeable tu# breccia.

Beneath the test-ﬁeld of Shirasu banks, it is found that the deeplayers on March are rather dry than those on January after rainfall test.

These results indicatethat the high-frequency CSMT method is relatively e#ective to survey shallow subsurface structures.
Key words : High frequency CSMT, Electrical conductivity, ,-D model, Groundwater, Landslide/0) 1234῏506 weῌsῌ*./+*+*ῌrfῌeῌe**++7/8 eῌe*++* r++ῌs++** Wm 7507 f 3 ,*MT ,Magnetotelluric : 9:῏"ῐ- 6 9MHz ;<#=8>0) ?@ ABCD3EFGH

9:4I7:4IJ8>0K LMNOPMQ ,Z-R:S ῍ ῎ T6 H, E UVWXYZG;T73 [ ,f- 7AB ,s- \[8>01]0) 17/ ^_3 +ῌe U]0`aQbM cQ

7aῌdeX "#Ifagh50G8,d- 7ij3 1 d 6 /*- ,rῌf- m 7]0 ,@ke e>0 ,Kaufman and Keller, +32+ ; ῍lm n

6opq[r-) MT 86 12astlm` ,s+333-) 1 Z adWX uvJwx ,ra- 6 ra+Z,ῌ

l`- yz7eXW0),wm- 8{|}20) @ke E+ZH 8>~ w 6[ m 69῎8>0)

QbM cQh} 9[aCD017U ~ `}?8lm3st7]01

Maxwell G;T6 : ,E- 79: ,H- 3=U\50\[:S73U῍8/0) 71886 "ῐ6[UJῒ50@U]~ ῑ] O

rot,E-+jwmH

῍rot,H-+sEjweE

῎a0@U6W38>0) ee ῒ|QbM

cQ3[ +* km 7]0[ +** "9CadW@`lm8 6 /* .

7 ¡0) @ke e 6¢῎ j 6£[¤¥8>0) +** m ;8>0) 117} MT 6 sl`3

 MT 86 dW}20[6W¦W +* kHzU§¨50lm7J©eX KU`

<#8>08 ῎ Tª«¬ , ­¢ῐ6®¯8

lmU°±8>0173I0) ?@ ²³ ,-*  2.*῏2/+, + :  CSMT   ,  ! "#$ %&'(   +*2 / ,**230



/(01&234!5&"6#71&389)*&
$  /:3;+%$& ;< ,6',< ῌ+CSMT>) +** kHz ?

MT ,/:$-A. Controlled Source 6',&/,6 0$ CSMT ,3EF,& 2 /,+ Hz- kHz6!'J& (K45&()$9N O:N;.P(<=& > (91Q5  ?<R'?S6TU<VWXY$Z,b(& c2d 2*% , + k+/* kHz?S

7(OD5 CSMT >6j;;< *+@> ,**, ; Fq@> ,**/ 2 ?S O HI C9i9 JKs( +** WmL

(= ) + kHz+0 & *+@> ,**,BC , m 3; .D . m BC

GH+& ;< <I;U LM(ῌ+CD$12$3'F 2 6 7(85>H<.[ \ ]@^A( 7_`$aef6ghJ23(%QB)*+,& C9i ; Vogelsang, +33/ klmnEo*+p  klmn

Gr( 7$efJ&OD(,23>) $
MNtuJ&&( 2 7vwx yz{y(O +-+-* m &  P|;5>H<  Q}$~,+2 %5wA(' v' ,HI$RSJ&5Q . m?S6%&23$% .N %$>

7 XY(OD35& 8 Z,

6',& CSMT , %%$9\5)>(<=H< ;>;$%&.

. DBC T (>+O D H<  3 ;>; )*<U7VWH+p) [5{3,,(<, ?<  

GH  ?

]( .0./ m 3^ $5&@_([Q5&<V .NJ >~..` m" a(OD35& ?< 74 .LI(91,<Vb,.DBC
6'1

7D_ %3c$dI e5 S$4f(OD35& )$ MT ,gS{6',& (hi&( bB$jQ ( 71&, Sk 7B4b1& c <V8MT  +

$ ,* 6lI<=H< 7B( +./ 6lI$5&$mn 2 CSMT ,6',<gy op $~,+¡¢ c*) _` 6q>) 2 /, r | s$~,+£t6¤9&- 

+332 u 1 ¥ +* v ¦§w¨ %x $% 9\5yx(;z; x ©(915{ª60«<  yx¬ª|­}®¯°± ,**+ ,**, u ++ ¥$ ;<$\?*<ῌ+~,²*< CD :,* m g  GH : c +0 m  S)>$J&<V$ CSMT. ³ I ^ A 66vw;<  ´ µ $ 66B&23(¶=& T_,.³
I6·~  2

$%H+)*&.³

I^A 22 ´µ $¶=5

ῌ +    CD, GH          CSMT     AB
!"#$%&'()*+,& -ῌ. +332
Fig. + The survey lines in the landslide areain Izumi. An open circle and closed
circles indicate a horizontal loop antenna and the observation sites in thehigh-frequency CSMT survey, respectively. The geological cross section
along AB is obtained by Yakabe andKobayashi (+332).

: '(! CSMT "#$)*%+&',- (.)*/012+,ῌ3-3145.

6/017/8ῒῑ῏῍ῌ῎109:;2,< 3 ῌ= >9?@A=2,BCD 49:;EFG HI  GH D

3 9:;=

 +JKL=56-MNO >9?@A PQ

DI<R2, 7S$)D89= MT "30BC :T=(U;V 7W XYZ(!

[\]9^[_/0<=>?@8<,NDI<V 109:;/0A67
3NO=  `]a:bc]def0/
>9?@A-BCMN 11  D(.QEIFgCG"=KN , hi`]a:bc]=Kj 
>9?kHI Ilm : Ogawa, +321
JK?:^n]op q:rSLst 2,NM$ῐῌ, +  CD    F   ῌ
 +332     cd :    An :   Tb :  !

Fig. ,The resistivity cross section along theline CD shown in Fig. +. Numbers inthe ﬁgure are the site name. The stripelines indicate the slope covered withconcrete blocks. cd : landslide deposits,
An : pyroxene andesite Tb : tu# breccia, F : fault.

)Nu n]op/07r! [\]9^[* /O2U5. v!D7j wnxy:?z K!{U=PQN MT "|R}"2,N
DS~7-TN 11D/0 CSMT $)
UV7,ῌ3-45.6/-WCD7N I/I1$)   CD X5. 1- m

K!

-PQNX x :xy:?z YI<,
7,O 109:;>9?@A=2,NNu
f0/ZA-BCD7N wnxy:?zZA [\/ ,**1 - hiV"2, ;@AI<,N M1wnxy:?zZAO=  ,ῌ34 - hik]2,7m707,- abMN 1 JK?:^n]op=KN -* ^  F DI<_  _ ."2 `+"- 'D7N1D-V

Wm S(@A/0307N rNP/N c)  deMNfg=7V;2,< 9:;v!h/0K!h*

N-WViN U=ajJ&k wnxy:?zZA 8!-ViN- ῌ+  F DI<(`]a:bc]=K8<30>9?ῌ,k]-7N1D/0 11-MNDQl0= El= MT "FgCG"2,>9?

<,N ῌ +332 ῌ+  AB =8 -@A  U 7N rNPVDV=UVM¡:¢]£/0(-  <¤j ῌ, =,D{N 1X [\]9^[ - O2+Y

I(k]  1$)X(.=8<KNO U <= ./* m =, I/I¥mIVMN 10PQ=ND D

1- m D,L',,ῌ3- 45.QEND <=` DQl0N- F Kj_ ¦,< §n-7,O  <= ,/ m XI."2 <= +* m o¨p7`  f ῌ- =  BCD 4=¦,< 9:; #D !+=Mj qJDQl= © l > 9 ? @ A    $ V  I  > 9 ? 0N :ªc) xy¬­[ ®rs,-N (4=¦,<  Ilm+ KL= ;D@A;-S~W7N( VMN 7¤ 9:;=I- ,±V F /0D«

/0tu0J-6v

<,N 11D/0 ¯°=¦,<  %Dῌ!=²X³wx*yj

WJ =K8<´ <,NJ ῌ (UJ=z{=µ¶I<,N& ῌ

1/0 D-`MN1D +* m <=X +332 D· |<,N ¸¹ $ ) } 0/=

!"# $ +*2 % ,**232

ῌ- ,     Fig. - Apparent resistivities and phase calculated in the ,D modeling and obtainedby the survey, which are indicated by open squares and closed circles, respectively.

&'()*+,-./01234 567
E FGHI J&K 1 0 567 .

sXE4  ?:1(D LmYBLfg=@A .BCD

'LMNOCB(PAQR ++, STUAV
(NW AX&YB( Z Z[Z\] ^_`abcde-fg=hi1j4.kl6- mn
v!wxy-zZ {Z Z6 |}S 4~E
F89:;<=>?

opcqrstuAS(N A = !"AXiYBL
 .BC1( AAh 1L PAl1k(!"A

.kl6- `ῌ.

6   + ¬ +* ! - ¬ ,3 ! , ­ ®¯" CSMT

j4 §  ¨©D ªD «DT  °±C®Y - m lD1i ,**/+, ¬ 3 ! +- S±C +0 ! +1 S´6T6 +,/** mm

(N¡¢£¤¥1¦²³1k( ²³c-`ῌ.
 Test bank 1µ¶4j4 §  MOD, # L+ L,  ª «( :  CSMT  )*

33

+%$,-./012345675%51
8.9: !"#; .9: !"#<=5> ? @A9.B<5 CD!-: !"EF<#1G H6%-9IJ$KL%&
MG$F
.9:?

!"#

@A9.BNOGPS'(TQR 8

12'(UVQ)*W$ ,**1 '( 1QXY+,%&M
L+ , !"#-.4QZ/[\]^4Q

_ 0`a 42 0* Wm <4Q 5  b1 c.

῍/῍2L,

f9g2-.3QRῌ.

 CSMT L+ , -   !
"#$%&Fig. .

The high frequency CSMT-survey linesof L+, L, and L- in the test-ﬁeld of theShirasu banks in Satuma-sendai.
Closed circles with numbers indicate
observation sites. The directions ofthe antenna are shown by arrows.

 d!eGh45$VQ iQ L-

 -9I5j56k$%lm78i4Q +/* kHz 9-9I :nG+o1

;<$%p1Q H -9IYG5q51!"#_$%  Gq5r1=>s"G$F4 tuv5j5w>-9IG?%65q5 QR<ax%6 @< (y5c.<,zA1<J4Q MT

0  G,zNOsqw<GB%621  y$  kH

KL%&MGW{9 +oqC|421  Dx7kEF8 P ῍++  + - }GH+ ; L-  -.&P>   L+ , G /*, 9

U1~6J ,m P 
 L-  -/P  5  L+Lt66M +./ PVQ L+ , 1~6

J$1KL%&M0Gh  4$4 HS5,zv  S, Ek,-./0

IJ pGKP , 1Q !"#8.9: !"# _Nk 4QKL%&M-9I12 Ob1

P> =>&P<ῌ. 4Q <$%Q,<@R !9! S>zSa

T4&

U4Q , %&M,-.?Q ,-. 8&St421 H<G:$  8.9: !"#1CSMT& & <T4&5"./'Ek5 675%51G JX41 L,

῍/* , JHXZ[421  5  =ῌw> C L+ ,  +,*+./ m, L-  ++* m P> 1Q  , kHz+/* kHz  +0  P

 +* $%5> D!-:aU42VW
./* m <4Q <ῌ0L+ + }< - }V"-* m i%&MA1 Y,-.<J

F\XY5%&M:]GK%6  H6t%q!9!J,z  NOG9 p
o2151QRP < 6  5  <^_>`zB¡9!¢Pc.



H%&M,-.$% £G9aJ XY ¤1 bKL%&McdJ

H<G:$  Dx7 + }¥e¦X0 f§Q + }< - }%&M¨©A1<P  , ª<ῌ/  ¥«Gg 0  V" ,*-* m  +** Wῌm +g -uv ¬­,z JSq©2>

S NOpq<9h°G51H<G:$ H<  G$1W³VWiTi ·©J %&MA1H< 5  4$4.  .+. m  +,* Wῌm P> t®«¯1

4$4 + - }± g / <g 0 ²P"  W<´³9,* m V

F%&M²µGj¶ S

Kx  kS  Hg 0 kS>¸¸

Dx7kG%&M<$%&M, @¹$%&M5 HH ,FGj¶ KG

JtkV"=5V2 > lm nV":]1  +*2  ,**234

ῌ/+ -  - Fig. /The resistivity pseudo-sections along three lines of L+, L, and L-, which observed on
January and March. The cross sections of the banks are also shown.

  L+ ,  L- +  -   ῌ/ *+'(, -  .!/0),12 )345

9 - :-;<! =>?@AOP(), :%&#L- QRS:TUJ(),:

1( V1! ῌ0 WXY-Z [\]

+  ++* Wῌm !c# -  +./ Wῌm ,`N?@(,)$) @n BC D5EF!

 !"#$%&'( )678GHI:J(,KL(MNJ(^_ +,/** mm ,P `5*D2ab:
dAefghi:j? keklkm

%6o0p qr 1@A0:/09s12t!u#OP

G!=O8Bb,KLOP vw^xy +*b,z{|OP( ^_}~Nb ty 5*ῌkeX* #b}p!{|b: .!0c+'(, +  0 mm, -  ,3 mm  "#$ - @{|OP@P w12 :P  ,* y*+#O] Q|| ,* 1- mm

῍/* 0P, )RS! A@P vw¥¦] + ,§JA @A - ¥/09s0b A*o"¨g@©

ª G:`NP}pJ( )),12 - «:V¬Nb ,)$:
P - ]ZWXY 5Q|­®

¯2C +* m EL+ Z:¡¢'(,£¤]WXY])) , m EZ + - :?@=b), ^_¥!`0:t!|°±²³´: ,/ yµ¶¥ +  !



ῌ0Fig. 0: CSMT

   L+  + - 35



The resistivity models along the survey line of L+, using the data on January andMarch. Triangles indicate the observation sites.

 !"#$% - &'%()*+,-./001./234&'2 (56 78 9

:;<5(=&32=>?@/2A6#B'CD2 (E/  CSMT 

OPQRS Tῌ+ &<534&URCSMTF'D2.@&GHI  JKL&32MN
JV=>?@/278;+WX./

&Y/5Z[\]Q]^ _`/EA65 (/@ab#c'deD2 Tῌ, f@ @f

MJg!2"#'h$D2iED'34& 8j , m D2+ +* m NE%k2

l=2m&no+% CSMT

p&WXF#$

+NE_J'(,)

CSMT &32 + "2(=+(f2 5\q; Z[_*AOPQRSr Q+QGHIKLs&,

8j-+ &c_ t &".D2+X/5 uv0wxw123yz{|}#(=E<#_2 47& ~5 * 6_&32ED2 ((&N7< 58

2(=f@ 9ῌ8&32*+ :;  <=F_56 de-+><_=?@ 8E @f&'"5¢#A5 Q+QGHIKL £B¤C¥QCSMT ~5*6_256 -78+_(=+F'G + ©D2((=f@ H +** m, -8j , m Q+QG
HIE -78+M +./ 78=78 +9)='"5 °± Mm&  M9²;=s& N³ ´+O' - µ¶m&+·¡5'+Q]QiDe&$¦E&'"5 F§#¨7<, IJIKª«L  ¬­®&"¯D"536  /2 : +.1ῌ+//.

ῌ ῐ ῏ ῍Kaufman, A.A. and Keller, G.V. (+32+) : The magnet- +333 :   p. --/.
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Ogawa, Y. (+321) : Two-dimensional resistivity modeling based on regional magnetotelluric survey
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otelluric sounding method, p./2-, Elsevier, NewYork.

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,-, Springer-Verlag, Berlin Heidelberg.

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