西村卓也 村 上 亮 Dike Intrusion Model of the 1930 o

ῒΐ /, (,**1)
- +.3ῌ+/3 ῕ ῔
+3-* ,**1 + 3 ,**1 . . Dike Intrusion Model of the +3-* o# Ito Earthquake Swarm Estimated from Leveling Data
Takuya NISHIMURA῍ and Makoto MURAKAMI῍
We examine vertical deformation observed by leveling during and after the +3-* Ito-oki earthquake swarm in
the Izu-tobu volcano group, eastern part of the Izu Peninsula, central Japan. Taking the mechanism of the swarm
activity after +31*’s in the same area into consideration, we estimate the source model which can explain the
observed uplift along the eastern coast of the Izu Peninsula. Although the observed deformation in +3-* allows
a wide range of parameters of a tensile fault as a source, it is reasonably explained by a near-vertical tensile fault
suggesting dike intrusion east o# Ito. The volume increases are estimated to be 2.2+*1 m- and +..+*2 mbefore and after April, +3-*, respectively. They are much larger than that for each episode of dike activities after
+31*’s. Broad uplift with no seismic activity was observed during +3-+ῌ+3--. It is explained by either a
spherical inflation source or a horizontal tensile fault at a depth of +* km, west of Ito. In both cases, the volume
increase is estimated about 0+*1 m-. Calculation of the Coulomb failure stress suggests that the dike intrusion
east o# Ito triggered the M1.- Kita-Izu earthquake occurred on November ,0, +3-*.
Key words : Izu-tobu volcano group, crustal deformation, leveling, tensile fault model
+ῌ ῐ ῎ ῑ ῏
qrs tu"#Ivw"xyz"$
)-\&{0(
+312 ! !"#$% &'( ,**0
. )*+,-*.
& +332 / /.-
(+) "# |"n}~}$# $
€% ‚ƒ„ P…†f.)9\&%‡+{
"#$% 0( 1 +31* 2
-ˆ&D$‰Š.-\&%( -? "#%‹
345678)9:; (Fig. +) $<8=>&
Œ-XŽ)9:= +* km 9:‘''‹
?: @A "BC "BDC)EF 0
)’>0“ }~}”•$=( +* km 9:‘
)
<8$G=> "HIJK$L-M>&'(
– 0—)"#$˜™(
"H<8NOPQ&*678NO-R
(,) ‚ƒ„#šb ›œ` ??žŸ ++*ῌ
GPS S8T (EDM) UVW W-X$'>
+,/ ¡: f"‹"‹ˆ&¢£¤¥¦)b)
9Y)-: Z[-"H$)-\&'
*L¡( §I+‚ƒ„# ›œ
( ]0 "##^_`a*b & "#
¨©),ª y--P( ‚ƒ„UV«
#^
[cd$Qe9Y)-\0( f>
ghi jkRlm !e! Aoki et al., +333 ;
)¬'& ..)UV
­« (1*ῌ2/ ) ¡¢®
$k'(
Cervelli et al., ,**+ ; Hayashi and Morita, ,**- ; Morita et
)?O +312 /¯IPQ&°
al., ,**0 ; ,**, ; Okada and Yamamoto, +33+ ; Okada
. +{-"HP/Y"#I +3-* )
et al., ,*** ; Tada and Hashimoto, +33+ ; Ukawa and Tsuka-
*% &' (Fig. +)( +3-* "# , hara, +330 )9\& /n9Y-"#%op
±h„P²¬"#I)> Nasu et al., +3-+ ; ³
´-*/ῌ*2++ µ¶·¬R!0¸ + 1
¹2"º""HIlm»¼ih
Geography and Crustal Dynamics Research Center,
Geographical Survey Institute, + Kitasato, Tsukuba,
Ibaraki -*/ῌ*2++, Japan.
Corresponding author : Takuya Nishimura
e-mail : [email protected]
150
º»¼%›»® &
Fig. +. Temporal change of vertical displacement at leveling benchmarks around Ito City (modified from
Geographical Survey Institute, ,**0). Vertical displacement is plotted relative to benchmark 3-,2. (Inset)
Location map of leveling benchmarks.
­ +. h]Ž‰"/0Š®¯°±# P~€ ,**0 ²$³´ /0Š 3-,2 µu;¶µ·
&®¯–u ­/0Š¸¹–u
,**- , +- - ,,
…†‡1)de5+; f,? +3-* MJMA /.3 . h]<ˆ +, hvj, +3-* , / 1 ! , "#$%
+, &'()*+,$-. /01
+; hvw]yz/0Š 3-,2 P‹Œ
+ ?hvw|‰u;1)de5
23145678 Tsuboi (+3-+, +3--) xŽ 29:45+; +3-* <=
/01)d&e5 +3-* -ῌ. +3-* ++ῌ+,
>+? +31* @AB?
CDEF
+3-* +, ῌ+3-+ + +3-, +, ῌ+3-- -
3-.. P‹Œ]hv … GH)IJKL;+M NO)&45+; P
+3-0 ,ῌ- 1)de5 5 1rs
QR Kuno, +3/. ST7UVW=
‘’“>+ +3-0 1b”
XYTZ[\ ]^__ (+33*) `
Tsuboi (+3--) •‘)–45+; ab+$c%de5+&+ `aK
~€K /01—sT7˜™
+3-* <f,/01T7g
LAGSAS P~š›œ ,**+ g+;) f
=IJ) +31* @ABh]i<
+3-* -ῌ. +3-* ++ῌ+, jklmnopKL;q\ XYTZ[
- - 1rs)5+&+ ~
+3-, +, ῌ--
\d&rs>+tu;
€ž45+;/01—s /01Ÿ
?5 1„u;?) ¡&+ ,ῌ ῑῐῒΐ῏῍῎
¢
hvwxyz{+|}/0z ~€
1—s¤! 5 z1¥#3
0 1 d451|}/0Š£
‚KL;12 +3*. 1
1‘’“)¦45+; 5
)Sƒ45 „] (MJMA 1.3) , +3,. `a§ ¨©ª«de5¬ ~
,3 - 1
89123'h +3-* 7-¹T#!º»ƒ¼`Ž1
151
!~‘$% (Fig. ,c) ’)“ !U<'8v
+3,1
* [K LHI”•H8vDC…'–
!!"#$% &'(
$6$%—M6:8v Abe (+312) !"
)* +, -' LAGSAS '.
HIŽ1J˜NJ* x' 97! /
)/0123 .)
o (Fig. -b) k7-@M8vGJ
+3-*ῌ+3-- 123'4 Tsuboi (+3--) * 5$%<=
+3-* 97!O
56*
™$%J˜Nš›@ !HI'MP#
789 :;<=6
hk7-@M$%'VIœ Q<=I
89>?@ +3-* ' ABCD
KR* 5 .ῌ, ž
“ŸS6* Fig. -c '
F! m GHI89J* 8
-d +3-* < % +31* U…LM%
98C'4 LAGSAS 'ABK"
'=Saq$% Iœ'r
IJ* Fig.
8E
.) LM>)INO
- c +322 /ῌ1 tD +33* 0ῌ1 t , o$%
P89K"Q)* +,RST
5o' +323 ¡_¢T£#{
*
#!$%"89C +* km U&M
7-DY6:7-p'f8vŒ
89C''VW0J$%"X('
Fig. ,a $%¤* mI Fig. -d +33- 0ῌ
W0)5'* Y5 +, Z*+
1 tD +33. 1 tm + o$% 5no'
[\] ^,_` +3-+ #?% ^7-` +3,2 #
GT#!%#{
* 5no'y
?% ].a 89 /, bcd,_e% D 3-..
Š8v7u 7-hk¥:&UVJk 8
bcd-7/% K"0fgH5'
v#zkT#!#{~ (Fig. -c) hkzH
I* 5hS'
0fgHI89K"i1Fj
* 5no8v 8v7u7-¥W
m 21Jk +,3'j+J*
¦X@M'C65D W¦8v§*
+3,.ῌ+3,/ D
Fig. . Fig. , - r
I89123
+301 m 0 4no57-p89
Fig. , 'l-!4
aE Ӭ'
r
I +3-* < %
aq$%r6* ms +3-* . tmno (Fig. ,
+31* U…LM%'=Saq$%Y©'
a) 7-67u6L' +*.2 cm 8vw
65V* +323 T#!%'=S8
)* x +3-* ++ tmno (Fig. ,b) v (Fig. .e) ”¨ ,* km @MD–ª'8v«m
L' +-.. cm 8vw)yk 8v#6
k 8v#Z¬ ­* 8v#Z¬ 9'zH* y +3-* ++ t w
­ +332 T#!'=S‘$% ¥[
6:FN +3-* ++ t ,0 ;97!
,**,% Œyk +3-* . tm8v®32
(MJMA 1.-) #{<'?@ 97!'=
¯ (Fig. .a) ¤* [K +33-ῌ+33. T#
S$%|m* xno (Fig. ,c) 97
!#{
no8v 8v#\z*
!|}noJ !~$%L' - cm 2
+3-+ D -- 8v (Fig. .d) 5°®32¯
1H* x97! > , o (Fig. ,d)
'¤* +3-* .ῌ++ t8v (Fig. .b) Y7o
J 5no'3?HI!%DHI'
®32¯r
*
DD@s7-@ML' +..+ cm 'A68vw
+3-* E~89U±‘$%w]
)* mI 8v# +3-* no (Fig. ,a-b)
‰²Jk 5°97! ³
€BzHyk Y‚2ƒ9„>%
?@* D
aq$%'V7-hk6:
* 7-@M8v +3-- U…C…„
97!<J´n'?@I
D
† (Fig. ,e) C…‡ˆ> .* oDI Fig. + Fig.
* YIœ , µ0 !o‘$%
,f%*
-! 97!'=S$%|m*
+3-* E~ 789,_D‰„
hH ‰²123D7-T#!%'=S
FŠ_p‹ + $6
DDHI* 'l-
‘$%ŸS65^
* mI 5#'¶_
noaq$% (Fig. -a)
·;)I 7- +31- ¸ +311 Œ k7-@M8vGJ* 58
JIœ ¶_123D +3-* ‘$%ŸS6
v 97!!HIŽ1 Abe, +312%
5V*
!
D97!4
JV* mI Fig. , ŒIhS' 7-@M
152
‘’“”‘u •
Fig. ,. Vertical displacement on the leveling route along the eastern coast of Izu Peninsula. Bars denote vertical
displacement relative to the reference benchmark denoted as Ref. Lines in northern part of Izu peninsula
represents surface trace of the Tanna fault system ruptured by the +3-* Kita-Izu earthquake. Data period is
written.
m ,. nopqrstuvO^wx. my Ref. Qzh{|}~P~<[uvO
^€‚ƒ„…P. no†1‡t' +3-* † ˆ^h‰Šab‹…Œ€
…P. ŽmH' myzh,1.
-ῌ ΐῒ῏῎ῐ῍ῑ῔
D /* EFGH:;I4J$4KLM9N
+ +31* OPQ'RST+U +31* !"#$%&
!"#$%&'
' +3-* VWXYZ['U1. B
()*+,-. /01234567
, \]O^'_`abcdef-QRST
89:;;<=>?@AB,C1+
+. gh ijk +3-* l]
[\]. +3-* ±·¸nmW¹Aº»¼#$
Fig. -.
153
Vertical displacement on the leveling route of Izu Peninsula. Symbols are the same as Fig. ,.
­ -. ±²³´[\žV~.wµ¶ Na“­ , :;
(Nasu et al., +3-+ ; Yoshida and Hama-
|./
}~.- wxT *./ km
da, +33+) +31* SQR) Period B k !"€T^
!"#
x€?>T`)c
$ %&'() *+,-./
0)
QR) Period C k ‚
ƒ„Wl^
/
fg €T / km S
1/2 34256!"789 +31* o7B Period A, B …†^‡
:; 2<.
=>) 78
2 ^
ˆUg`. 1/2 342
9?>@ /
) ABCDEFBG
‰Š d#$e [56!" d‹$e
HIJK
)L789MNO
MNO
, Œ#$Ž@
P.?>OQRSTU. Matsu’ura and Hase-
56!"€T +* km ‘>) //2
/
) ‹$
gawa (+321) V WX
O
’)789“ QR”•–.2 M
YZ Okada (+32/) . [\]
NOP.?>O—'˜™T
^@_`Na +3-* . bc2 Period A dFig.
ABCDEFB  [\‰a dš
,a .ae +3-* . bfg ++ b Period B dFig. ,b ›e œŽ [\]ABCDEFB
.be +3-* ++ῌ+, bfg +3-- - b Period C dFig.
@  [\žx‰Ÿ \
)¡[
,d Fig. .de hi/
) NaMNOQR
\‰œŽ
).<.^ š
STU56!"789?>) c
›œŽ./
\‰¢
j Period A B MNOk lmnmW
.£¤¥¦§}~./
^2¨. ©) š›
l^o/./
fg +31* pJ
œŽ ª«Jf
¬_`.
56!"#$qr2<. +,*s
) tuv 2*s
2 Fig. . 2­’ ®]OV¯#$.Y
) c Period A k !"wx^yz{
ZO°
®]‰x‰ \
)œŽ
154
ƒ„…†‡„S ˆ
Fig. .. Vertical displacement on the leveling route along the eastern coast of Izu Peninsula. Horizontal axis is
distance from benchmark J/,. Data period is written.
n .. opqrst uvwxSyz{|>} ~
7W n4./‚
] J/, #uvS)€5 Vn
s : mm U. V7WXYZ[\]^_`ab
sa ῍ ῌ L : : km a : Fig. / 45
!"
#$%&'( *.22 )* (+,
-./0&123) Table + 45 6
. +3-* 789:;<1/=>?@A(4.
.+
BC DEFG *.+ HI 5JKLMNO
Period A (0&1XYZ[ abG +31*
P 678Q5;< DEFG *.3 RST
cdRefghii`j\XYZ[klJ5m
Aº‰ghiM +3-* <»O¼789:€‚£¤’g“
Table +.
155
Estimated fault parameters4
,**, ; Ukawa and Tsukahara, +330) Period
B !"#$%$&'(
)*+,-./0 !12%3
456789:8; +31* <=>?@*3
' /0 !ABCD
!EFGHI
+ /0 !J2K(L
Period
B /0 ! Period A M(NOP3
Yoshida and Hamada (+33+) M +3-* < - Q /
Q:RSTUV6' S-P WX)* - Q
YZ[)12\
L( ]^_`
abc6d
]^_6"efZghij)* k% l
/0mnohi p3q3rsthuvwx
yd(z{|(& \)\ - }
6d~}fx\
€‚EFGJ2
K(ƒ„c…†&‡| 3 ˆ‰ŠfZR
)*‹S+&ŠŒ'4Ž fC~}f
ƒmnohi')*6d (Okada, +32/) ~
} Period A B 6p3q3 2.2‘+*1 m-, +..
‘+*2 m- 6d +323 <>?789:’g“6 +
”,‘+*1 m- 6d Cervelli et al., ,**+ ; ,**, ; OkaFig. /. Location map of the estimated fault model.
The rectangles show the locations of the estimated
tensile faults. The solid line on each rectangle
shows the upper edge of the fault. Open squares
represent the leveling benchmarks as of +3-*’s.
° /
12%3 !’g“CD ±²1
2%3/0 !CD³\ ´[µ¶
·6³ ¸¹G +3-* <=AºŠCD
³
da and Yamamoto, +33+• –— ~}
\
˜™)*š›œ& +3-* <78YZ6žŸ
œ '¡¢¡£¤d— | M¥.
>"9:¦˜6j
§ +3-* <78YZ 1* ¦6d
( (Yoshida and Hamada, +33+) +31* <>?8;\
78¨©sƒª
« +322 <78 -3 ¦¬
œ6 +323 <78 -- ¦• p3­® p3>¯
¨©s6 +/ ¦>e6d M
9:YZ¦˜)
yz{|¸z/ }
156
TMN9šN9›œJ0#€)
"80#MN" )I
UVJ
(+33*) +3-* =98gU8_
(Nasu et al., +3-+) !" Period A # +323
c™
GPS ž SAR OV0DE
$%
&'() /ῌ+* km *
O M2 d
Ÿ u z@Ut Miyazaki et al.,
+," - #*
,**.| “)? M1 d
WX
—Y¡C
.+/
/ km 0 +,*1 234 0*1
56
V0 zZ¢0| @ z@Ut Fialko,
)&')7"89 :;)
,**. ; Nakano and Hirahara, +331| ?9 "," h^
56
* *#!"&'<
£¤ - =
[, –R™
F}Z¢0)
#+
=98/ *./ km ,>
9gU \< V0 zFig.
$?89 :;)@ABC"DE %
,c Fig. .c| ]¤8Z¢0 zFig. ,d Fig. .d| - km F?G+ &4)956
799W^) _ WX
Z¢0
20 H I
JK Table + '(
0]¤8F9?? Q . `
)L*!
+ "," :;)"5
F}Z¢0)+a"9 \+
6MN MNO>PQ+R
Period C 0†y (Fig. ,d) ¥
- „
0
, (RMS) , S-.F? PQ
Q
†y (Fig. ,e) b?¦) ¥
- CQO>79
)/T)9U O8 V
„) IH)F}"89–R™cid§8
01?+MN2+9W3
j> 0F9 Z¢0mnopqO8
4
XY, Table + "$)Z4
56
0†y
„0¨+)7
MN[5"
z@Ut Pollitz et al., ,**+| e©„)ª0+OW
MN
59 \], + 67
†ygU?9 \« fg
™hi
-O/^0
_)` 0#
j
¬ER™)­k0˜99W^)
MN
+ 8
56)0 234G
Fig. -b Period C Œ®— / „
0)
+9W9aJKb" +3-* $
©„
/^0
7–R™¯“
) M /.3 c+ M/ d
:*e;"
t / cm -.F9 –P
OWl]
89 f<WV0g
JK
Z¢0
†y :*
Z¢0
="899 +31* >hi
$j98 M/
mnopq (Fialko et al., ,**.) g="8
d
kk;"89 ??
°"8^±gU –R™i
l]
mnopqr=)> I&s7
¬ER™)70˜9` –R™
/^0<\9 @Ut Mw 0.* aAl]
F}Z¢0gU
G
<WV0 BuCvwxyD z{E
©„
0#'(lmn!
›œJ0#
,**+| b"JK c -cm -.) "8 I
²³o,´+a
Period A jOk B /^0
*Sh^
"9 –R™)­k%}899
)
) +3-* F}
~€‚ƒ
)
, Period A, B OW$‚ƒ"
9W„…99 "," M
gU] $
‚ƒ)+
N
†‡m <WV0Gˆ"
)79 0#
/ 3 km -.+t –µ
O‰Š?‹ŒH89gU H
‚ƒ)0)7 :;)
F}
€ :*
‚ƒHH>
)Ž
Period C 0²p¶"89 +33- , +33. s
:KC€IJK)79 V0 (Fig. -d) ·+0#MN zqr¸s
 L89#!" (Yoshida and Hamada, +33+)
,**0| ¹g ^Žt#šN
, _>
0#
†
s,:*
0#(‘C’r+MN\
‡mA I
DE (Table +) sº
“)9
) :;):”MN•O"
JK) '()L 0»+*1 m- -.)> uv
,
wR™°+ +* km -.
0#
.ῌ,
+3-+ῌ+3-- ῔῍῕ΐ῍ῒ῎ῐ῏ῑ
zFig. / Table +|
:;) –P—Q , „
Period C zFig.
šNMNb"0#) šN
x
,d Fig. .d| ˜–R™
F}=98 S
% I¼ +* km b"89 qr¸
+,-
./0 +3-* Z[ŒTU•–—˜"A.@
157
Fig. 0. Coulomb stress change caused by opening of the estimated tensile faults(CFS). A thick gray plane of a
beachball represents the mechanism for calculating CFS. Gray region is positive CFS. Contour intervals
are *.+ MPa. No contours are plotted in the region where absolute CFS is larger than - MPa. Left panel
shows NS profile at +-3.*žE. The star represents the epicenter of the +3-* Kita-Izu earthquake.
Ÿ 0. ' +3-* ¡¢£A.@—/¤¥‹C lCFSn* Uˆ¦§¨©6 CFS
ª«'¬­®UL€‚¯4* §¨$°CFS ±$°* ²³©R´6 ** +
MPa µ¶³ -MPa NO²³©6¯* ·¯4¸W¢6 [¹ +-3ž% ¢* º
»6 +3-* Z…UU¼&4*
(,**0) +33-ῌ+33. SAR p'%q)D'r*
3 km +- km,
.- 1 km !"#$
stVuvUwxRhyz{'
%&'()* +,-
./01
6E|2}B1 stVU4`
234'56 +- km 78'
~`L€‚} lrƒ „t ,**,n*
2 9:6 1 km, ;$<=
6 ../>
Z…†UmstV( wxRhyz{
+*1 m- * ?@A.@B;$C
B1 Thatcher and Savage (+32,) 6 iy
6 &4DEF786G
) ++ km st‡ˆ]‰Š‹
HIJKL/0&M1 , NOG
C
6*
(M 0.1) !{Ž'‘r* `'
PO (,**0) 6 QR+,-
./0STU
+3-* Z…U +32* Z…†[ŒU
TU’“”U(
•–—˜"‹C
VVC4WXQR GPS Y-./0
™š‘r (Morita et al., ,**0 ; Ukawa and
Z[\ +* km N?@]^_^`1ab4
Tsukahara, +330)*
B1 cdefgh)* +33-
Thatcher and Savage (+32,) 6
Z…U{Ž
+33. ijk';$<=
'
6 +.2>+*1 m- lm
# iyˆ]‰* ,**0n )1
+3-+ῌ+3-- +301 +313 +,-
ef
+ῌ- )* QR6BB
iyˆ]‰Š3v
;$<=o86
›`D'6
+33-ῌ+33. +3-+ῌ+3-- Z…U{œ Period C )1
c]deª]Œ a
158
Period A B ! ""#$%&'(
)*+,-./ 01CFS ; 2 3
,**,4 56 *+,-./567
89: *.. ; <= / km >
"(.)? +-3@
./ Fig. 0 (A) Fig. 0 BC
""DE *., MPa .FGH
"-IGJK.FI(.)GLMN
BN! +3-* O"P(BN! " G!QNGR
/ῌ ῎ ῍ ῏
>S"#(BN!T"= +3-* O
"P($U%V &'
RGLMN +31* (WX)Y
*Z+[ (+,*@) \]^ (2*@) ;_`
+3-* (
!,-F# ,.-a+*2
m- (. +31* (WbcO"P/d
! ef0R " g +3-+ῌ+3-- %
V 12345(hi<= +* km j
kl mknon6-(BN!&'R ,-
F#7 0a+*1 m- l BUY 85p
q<59: +31* (g1WrP
#$%&'*;l Q +3-* (B*+,-./56M *
++ s(
"
(BC
G
<t=
ΐ
ῒ
u=>vwxy( z?{|(}~ R @ABy( €C3D(‚ !}ƒA
Q , EFE„G…(B†#,‡ ˆ‰H(lCIŠ(J‹lN ŒKchB
LMNŽ‘’“”B•(–— Q)
ῐ ῕ ῔ ῑ
Abe, K. (+312) Dislocations, source dimensions and
stresses associated with earthquakes in the Izu peninsula,
Japan. J. Phys. Earth, ,0, ,/-ῌ,1..
Aoki, Y., Segall P., Kato T., Cervelli P. and Shimada S.
(+333) Upward dike migration during the +331 seismic
swarm o# the Izu Peninsula, Japan, from inversion of
deformation data. Science, ,20, 3,1ῌ3-*.
Cervelli, P., Murray M. H., Segall, P., Aoki, Y. and Kato,
T. (,**+) Estimating source parameters from deforma-
tion data, with an application to the March +331 earthquake swarm o# the Izu Peninsula, Japan. J. Geophys.
Res., +*0, ++,+1ῌ++,-1.
Fialko, Y. (,**.) Evidence of fluid-filled upper crust from
observations of postseismic deformation due to the +33,
M 1.- Landers earthquake. J. Geophys. Res., +*3, B
*2.*+, doi : +*.+*,3/,**.JB**,32/.
Hayashi Y. and Morita Y. (,**-) An image of a magma
intrusion process inferred from precise hypocentral migrations of the earthquake swarm east of the Izu peninsula. Geophys. J. Int., +/-, +/3ῌ+1..
u=>v (,**0) Kr "OPQR
S 10 ,+/ῌ,./.
˜™š” (,**,) ›™ ZœŠžETIh
R0"ŸQ ¡¢#$%&'(M£)
¤¥¦*¡ €§¨ +++ ,,,ῌ,-,.
u©UVª«WX¬ªYZ ­ª®[ “ª¯°\ª
±]^ (,**+) >S"#*²M³H_`2
+** ´rŒµ u=>v7S 30 ,-ῌ-1.
Kuno, H. (+3/.) Geology and petrology of Omuro-yama
volcano group, north Izu. J. Fac. Sci., Univ. Tokyo, Sec.
,, 3, ,.+ῌ,0/.
Matsu’ura, M. and Hasegawa Y. (+321) A maximum likelihood approach to nonlinear inversion under constraints. Phys. Earth Planet. Inter., .1, +13ῌ+21.
Miyazaki, S., Segall, P., Fukuda, J. and Kato, T. (,**.)
Space time distribution of afterslip following the ,**Tokachi-oki earthquake : implications for variations in
fault zone frictional properties. Geophys. Res. Lett., -+, L
*00,-, doi : +*.+*,3/,**-GL*+3.+*.
Morita, Y., Nakao, S. and Hayashi Y. (,**0) A quantitative approach to the dike intrusion process inferred from
a joint analysis of geodetic and seismological data for the
+332 earthquake swarm o# the east coast of Izu peninsula, central Japan. J. Geophys. Res., +++, B*0,*2, doi :
+*.+*,3/,**/JB**-20*.
]Œ a (,**0) 5O"P(b¶)
r _›™€·¸OˆŽ B,3 2/.
Nakano, T. and Hirahara, K. (+331) GPS observations of
postseismic deformation for the +33/ Hyogo-ken Nanbu
earthquake, Japan. Geophys. Res. Lett., ,., /*-ῌ/*0.
Nasu, N., Kishinouye, F. and Kodaira T. (+3-+) Recent
seismic activities in the Idu peninsula. (Part +.). Bull.
Earthq. Res. Inst., 3, ,,ῌ-/.
c]de (,**,) ¹º™(hi›™ (
B"‡»¼»,o €§¨ +++ +00ῌ+1..
Okada, Y. (+32/) Surface deformation due to shear and
tensile faults in a half-space. Bull Seismol. Soc. Am., 1/,
++-/ῌ++/..
Okada, Y. and Yamamoto, E. (+33+) Dyke intrusion model
for the +323 seismovolcanic activity o# Ito, central
Japan. J. Geophys. Res., 30, +*-0+ῌ+*-10.
Okada, Y., Yamamoto, E. and Ohkubo T. (,***) Coswarm
and preswarm crustal deformation in the eastern Izu
Peninsula. central Japan, J. Geophys. Res., +*/, 02+ῌ03,.
Pollitz, F.F., Wicks C. and Thatcher W. (,**+) Mantle
flow beneath a continental strike-slip fault : postseismic
‘5’“”•–{ +3-* —˜™š›œ“
deformation after the +333 Hector Mine earthquake.
Science, ,3-, +2+.ῌ+2+2.
Tada, T. and Hashimoto, M. (+33+) Anomalous crustal
deformation in the northeastern Izu peninsula and its
tectonc significancetension crack model. J Phys. Earth,
-3, +31ῌ,+2.
Thatcher, W. and Savage J.C. (+32,) Triggering of large
earthquakes by magma-chamber inflation, Izu Peninsula,
Japan. Geology, +*, 0-1ῌ0.*.
(+33*) +323 +3-* !" .2" ,+ῌ,/.
#$%& (,**,) '()*+,-'(./01
2301243567/189
: ;<" +++" ,--ῌ,.1.
Tsuboi, C. (+3-+) A note on the results of the repeated
precise levellings across the Itô earthquake area. Bull.
Earthq. Res. Inst., 3, +/+ῌ+/2.
Tsuboi, C. (+3--) Vertical crustal displacement in the
159
seismic region of Itô, on the east coast at the Idu Peninsula. Bull. Earthq. Res. Inst., ++, .22ῌ.33.
Ukawa, M. and Tsukahara H. (+330) Earthquake swarms
and dike intrusions o# the east coast of Izu Peninsula,
central Japan. Tectonophysics, ,/-, ,2/ῌ-*-.
=>?@A (,**-) BCDEFGHIJ K.+0Lῌ,**+
MND " 0*/p.
=OPQ (,**+) RS - DT UVNDWX Y"
-10p.
Z[\]- ^_ ` - a$bc- de f - g^hi
(,**0) jk SAR lmnopqrstuvwxy
z9{|}~€‚ƒ EF5 S +*0
„…† ‡ˆ‰" +.-ῌ+...
Yoshida, A. and Hamada, N. (+33+) Redetermination of
hypocenters of foreshocks, mainshock, and aftershocks
of the Kita-Izu earthquake and the Ito earthquake swarm
of +3-*. J. Phys. Earth, -3, -,3ῌ-...
RŠ‹ ŒŽT