¹º '< h .0 »< --ῌ-0< ,**, gStructural Geology, No. .0, --ῌ-0, ,**,j




Preliminary report on the stresses detected frommesoscale faults in the Middle Miocene Amatsu
Formation at Point Matsugahana, AmatsuKominato, Chiba Prefecture +ῌ,ῌ-ῌ !".ῌ#!$/ῌ%&'(/ῌ)* +0ῌ,-./1ῌ
,01/ῌ2341
A. Yamaji+, Y. Yamada,, H. Arisaka-, M. Hirano.,
S. Iida/, T. Imamura/, A. Katoh0, T. Takahashi1, A.
Takao/ and T. Yamaashi1,**+  -  +, +Division of Earth and Planetary Scieces, Graduate
School of Science, Kyoto University, Kyoto 0*0ῌ2/*,,Japan, 
JAPEX ResearchCentre, Chiba ,0+ῌ**,/, Japan- 
JAPEX Akita O$ce, Akita *++ῌ*3*+, Japan.

 !"
Teikoku Oil (Venezuela) Co., Tokyo +0-ῌ+*-1, Japan/#$$Domestic Operating Division, Teikoku Oil Co., Niigatah+i)*+LMNef ' gZ[x®\])^_j 9H4¯64 ' gaj %7°4 'i 89v
O g+33/j 7±:£ ²%+y4uY< u 4 +ῌ;_³+ῌ$ +.<=7W´;µ4+9¶>:G gbj LMN·?¸3/*ῌ2/+,, Japan0

%&  'JGI, Inc., Tokyo ++,ῌ**+,, Japan1

(JAPEX Co., Tokyo +.*ῌ***,, JapanKew words : multiple inverse method, stress ﬁeld,folding, polyphase tectonics, Boso Peninsula5678)*+,-./01234 56789:;< =:>)*+,-./01?@A7%
BCDEFG H4IJKG*+LMN9< HKO
JPQR,BSTUKGV.W>;X01)*+LMNY< Z[\])^_`a4bc
dBef:G gh + ij HD.Y< k9:;lm:GnopT:;Cq< rso4+pῌ.YUtK
1 uvO g+32+j .w19< HKYx+y\]+u 4)rso +z{4+|B}q< ~Y 3+* Ma B}1 g ῌ)< +330j +4
Y N0.E,+NW B}1 D4 Y!:"B1)UUBYE>p< #4$7.Y% ῌ
& g,**+j 4w.<  7.01>WO
4 '4LMN7PQR,B:;JK1"
NM4u(.)01E4p!*B}
1 :GpF;< ^_4LMNOJJK1m.
/01 XBY< DK7:E>
9:;\]+Y+BY>Gw.P4*+.wF;
JK;>1 guvO< +32+j ^_.C>; N-S
OJ NE-SW 4)*+p,.-.01 HKJ4
.z./9< +* m }Gq¡4)*+p¢JK1 :O:04op1£:;>;< ¤¥7¦§01G¨.*+27Yp0D9p3©54:
< LMN4JKE>)*+POFG ªKªK
Y5 + «¬4¦§«¬4}>­. +3 ¡-4LMN7¼ 33 ¼

H bῌHVc®ῌ/¯°dῌeT±²ῌfV±³ῌgh´ῌµi ¶ῌ·¸j¹ῌ·'ºdῌHkl»

+
%345:;< +  +   :;< +ῌ, ZU (lnῌ)n  -ῌ. Z ¡l n ) n  / Z  # $ %  normal, reverse,
sinistral, dextral %<¢῎ῌ&I7JK k  , +' 1 ,LMJ N EFG OP - )Q  R
SBT s,Us- ῌ s+Us * 'VWXR +'VYR 0 ' Z'[VR  - )\ ]^ !"_#+  `<abcde f gK5h4iM g + * Rk$ ! "_ 0 j( `<abcde % l& s+ Vln)n ' m ((M s- V='7 H +333 ; Yamada and Yamaji, ,**,' (M)n op !q)QM  ""_ %' *rF)B "_( ' s+ V( % l& s- V Rst+M du%<; a, b, g, d, e, z  0 j vmM
R0* R a, b, g, d, e, z   ,  vmM)w normal faulting regime , striki-slip regime  reverse faulting regimeRvmM +B-,, .du%<;/xR ,, .du%<; a, b, g, d = e  z /x0
῍+3   ,   +   >?qB+'[':;< , * -]^ n"_  U£¤  U£q ¥g ¡( \g)]6 \g#$%¤ \g , ^¦)m _ U , ^ \g§¨)B"  `§¨,7'! Q + ^ \g%©ª`«4i ¬£ ­a)(+B#+-  F('F+   strike-slip  dip-slip   ,   !"#$%&' ()*
N-S +' NNE-SSW , -  NE-SW ). , /) + 012 %345 (6 0(%34' , /) + 78
5 (+'&9:;<= > ?
@)ABCD;5 8+B0 EFG H +333 ; Yamaji, ,*** b ῏y1 FGzB 2o3)w8 {| Angelier and Huchon +321 )AB4567'}~8)w - * R9:
8' +' NE-SW ( WX NNW-SSE (WX NW-SE ( Y=  + wA R 0 j  R b wA a I1A1(R) +7' ;<)VM   =\ R+v
}~8 >?+' a +' z , 0 * R
0 ' -Bql@qA
vmM/B+'vmM R Yamaji, ,*** a 'R a  d @01R  b, g, e, z =BC qA/1DE
 FG  +  + =0  + H= M')s:;<BvIJK=R a  d  normal-fauling regime = LAM--BqA/B+'vmM  ,* R >?N+' ,/ km @Oq
PQ  R S  + a  )w[TῌH +333 UVGW~ X!FG+.* Ma Y +'N :;<+' - *¼ 34 ¼YZJ»  .0 ²/0[1/0.[\./#  -  x p% (R GH e ¡ \.¢B!£n k ¡  ¤ +*  2 1 ¥¦§¤ s+ ' s- '(I¨)>*©ª% a # z « 0 ruHG¬C$ ruHGIYV+­HP®¯r°±²  + ³±´I'+ Bishop B µ¶$'¬C$ +·¸¥ s+ '(I'% ,C$(- s- '·¹.¹I'+,' º NF : normal faulting regime, SF : strike-slip faulting regime.

 Yamaji, ,*** a  Yamaji ,*** a  B  C   B  *./   b  g   !"#$ %#%&'()* +  b  g ,-./ B
 C  0123  +!  b4 C  d4 B $5 ,6# #$7
.89:#  Yamaji ,** a  B );.ῌ <.=>?  C  *./@+.* Ma A
%B%C$
DEFGHIJ KLM#+33* NIO% PQRSTUVWI
%XYZ[\.9:0C$
%]$^GP   _`aGbc %#% d\.IefC$g h%$[\.iI$C-UYZIj+ ! DE$k$"lmn[\.# I%!op Jq^rstruIv+  w$"l# xn[\.FGHIyz+ !῎

῍#{|}+~ $% ~ῌ&$ ~ῌ$ ~ῌ ~J-|  FGH'I%C$
p$ %CI'+῏ῌAngelier, J. and Huchon, P., +321, Tectonic recordof convergence changes in a collision area :the Boso and Miura peninsulas, central Japan.

¼ 35 ¼

$ %ῌ$\°±ῌW²³ῌC´^ῌµ\´¶ῌ·~¸ῌx ῌ¹Fῌ¹Yº³ῌ$»"Earth Planet. Sci. Let., 2+, -31ῌ.*2.
ῌ +330   +*, 1/2ῌ10*
!"#ῌ$ % +333 &'()*+,./01234567 :8
+9.: ; < +*/ /1.ῌ/2.
=>?ῌ@A BῌC$DῌEFG# +32+ HI0 0JKLM N/ OP + QRS TUV +*0 p
W X ῌ FYZ[ ῌ $\]^ ῌ _ ` ῌ $a
ῌ +33*
cdefghibῌ!
jk-lJK ; m no. -. ++1ῌ+,0
noῌpb!ῌ!
ῌῌq rsῌtuvῌwx yῌz{O|ῌ}x~ῌῌ
$ab ῌ =>? ῌ EFG# ῌ   ῌ  ῌ $  ῌ  ῌ  ῌ 
ῌA# +33/ 90 + : +**,***  ,  TUV +*3 p\ ῌ$ % ,**+ 514567: ¡¢£ ¤¥¦1234§r¨6©95©9ª«   +*1
1++ῌ1,+$ % +333 §r¨6© : &'(+¬­4567®© j¯ .- 13ῌ22
Yamaji, A., ,*** a, Multiple inverse method applied
to mesoscale faults in mid Quaternary sediments near the triple trench junction o# central Japan. J. Struct Geol., ,,, .,3ῌ..*.
Yamaji, A., ,*** b, Multiple inverse method : a newtechnique to separate stresses from heterogeneous fault-slip data. J. Struct Geol., ,,, ..+ῌ./,.
Yamada, Y. and Yamaji, A., ,**,, Determination of
paleo-stresses from mesoscale shear fracturesin core samples by means of the multi-inverse
method. Jour. Petrol. Geol., ,/, ,*-ῌ,+2.

¼ 36 ¼