  //  (,*+*)
 0  ,/+ῌ,/3 


y z ® ¨

Groundwater Flow beneath Volcanoes Inferred from
Electric Self-Potential and Magnetotellurics
Koki AIZAWA+    / "#$%&'( ( )*+*,)*-.$/01234$/ 5)05&*234/ %&'(63,ABC%&'(D E'(01234/BF
)0O5PQ0'A/)( *%RSTU

\0#%*]^.$/_1&`/(Kagiyama et al., +333 ; Hurwitz et al., ,**1) &2*

A54fDB3P&5g*((8)hU 0 

Ap]qP/Q0rsM4$/ (Lopez  !7! 8"9 :;<=>?#@$%GHIJKD)LM4$/ %&*$ NV+,W,$/0$XYZ-.[(/34$5$!a )P/0bcd4/ e3
i6  Q4(jkle3'7;mG<no<(t*-/ u95:;BF SiO,-H,O v'
<*-.j=*B OH w63Txyz

and Williams, +33- ; Reid, ,**.)

>{(Q4|'}~?*-/%& )@
a.AB  Q4|'aF

AAA*- Si-O 0B*CP/Da12/ E,G A

H +33/ ; Revil et al., +333  QD j=B

I' ,+ J KL%&MN NaO

C*k H K Na #PSyzAV

P/aG$B L'(Q*}~?63R?M

34 e3S*PbpT,byn

4/ %&U V @0 N4*-WM

54/X'M4/ (Fig. +a) e3S'(4/ )*$/ , Y'Z -ῌ/ Y'PBb[(\.&'`/ QQ'Oa 0 Y'(]^*$u9*kSy( c*-e3*_*`

/ 5 L'a$/ ¡U¢TP/ ,B. /0



C%&'(

b



 0$.Ba£(c*( ;e3SSy()*cd4a/ Q

¤5w¥U¦$§[(dp Ne¨(5/p>f(©C (convection current) 0ªd4 *

*«.B

ghV+P/ij (conduction current) 0cM4) (N43_a¬­ -®¯5

D0,a$// 5 e3S'A°PD (slipping plane)a z ±<R 0ª² ³YZ*-Nk

,,ῌ+ 

*(T,$/ N' m¶·7¹UaRWP/Q0°l/ z ( 0©C
W[-5]qa´²¢/q7'` !µ¢'(5p nk& *D¸TP/op['`/}~0*-.qjM4/r-X* st!ῌv'( e3iaº$BDa»u-*@$ SP : Self Potential D

6*-Pb)=*cd4/Q0$ pf,p( Spontaneous Potential v 0ª¼ %&'(½63wxM4/Q0'`/ cd4/b[(nk++-ῌ**-,  +ῌ+ῌ+ Earthquake Research Institute, University of Tokyo,
Yayoi +ῌ+ῌ+, Bunkyo-ku, Toky, ++-ῌ**-,, Japan.

Corresponding author : Koki Aizawa
e-mail : a-zawa@eri.u-tokyo.ac.jp

;<=

252

Fig. +. (a) Microscopic view of convection current generation by electrokinetic phenomenon(b) Schematic illustration of negative correlation between self potential and elevation. In
the porous rock, electric charge is conveyed by convection (convection current) ; however
no charge is conveyed outside the porous media. Therefore, the charge accumulation
occurs on the recharge and discharge zone. The conduction current (Ohmic current) ﬂows
to cancel this charge separation.

567

849:$ pH  49:$ ; ,ῌ, ῔ΐ῏ῐῑ ῌMT ῎ῒ῍

23> (Ishido and Mizutani, +32+ ; Hase et al., ,**- ;? @>A% BC

Aizawa et al., ,**2b)% D 8>EFG

4HIJK3LM $ NO #P+ ,-$ ./0 1 234 (Morgan et al.,QRSR 4T$ #3!4+323 ; Tosha et al., ,**-)% UQ0 $ V$T$ 

"\]#$+FV%^>?W7XYZX>U$ LM

G!![3

G_`3 + & +*a !4% %HIbcd 'z  $ e&'$ B((-m) f(>C') hij#k$ *"l #k9:$ F

Zmno5X+,3-p

?T

)g

>4%#./q '8G+-r $ skt3#+uk01

v$ ,***) N$ mwX (Gaillard and Marziano, ,**/) xf%yzZ2{ (Sill, +32-)%  %(> ?a#|A% LM}3~U.

yzZuj!K*3% 4-GM4/q $ .J uk,5$"$ P

! $ M6%yzZ$ xd 5 K3567*l %yzZ.K3$ M8

uj!/0 9" ',501)% 84 37 (Fig. + a) E! > (Fig. +b)% :8

Zmno5X x;#|,5(; 7< LMUAG=$"$ f(> ?a '8v$ ,***)%

_`3%?J > MT ? $ yzZ !@5A
G G" 9-BCD#|$ $^LNEF _`3% 4-G

LM $ :8; 7<-$k> ¡¢GHI$ LM¢B_`J,5£B~->4K¤MxML3 Fu

CA% MT ? $ -B.uj!M1k; 

3 ¥,_` $ .A¦§N^U5



8>j!4 (Fig. ,) (Aizawa,,**.)% $  $  7¨z©ª7«?uj!?J >% MT !"# (Michel?¬­and Zlotnicki, +332 ; Aizawa et al., ,**/ ; Revil et al., ,**2)$®¯°z 7 ^kN4% MT ? 

BE4!

O (,**3) u_` P  Q ­>k"\]±%N$ ?J

²z³w>´pJ uk$ J µ3#¶

/0 2{Rp A·-UEEA

¸ > ">44¹ STP (Static shift)   %(Ishido, ,**. ; Aizawa, ,**2 ; Aizawa et al., ,**3a)%

Static shift _`PY7º»¼9:$ ./0

57¨z©ª7U ¦½$ _`P

;<=>?@AB %CD EF0

253

Fig. ,. (a) Self-potential distribution around the summit of Mt. Fuji volcano. Contour
interval is *.,/ V. Star shows the reference point (* V in the map). Thick lines
indicate the locations of the summit crater and the Hoei crater. (b) The
self-potential data for the long proﬁle (site locations are shown in Aizawa, ,**.).
Horizontal axis of the ﬁgure is the horizontal distance from the center of thesummit crater. (c) Topographic proﬁle for the data shown in Fig. ,b.

G4H9I J KL9M'NJ O

PQ A

 (Ogawa and Uchida, +330 ; Sasaki, ,**.)

ing zone 0UV."#W"XHPQ B %R %S#(0T Seal-': Y: Z[\HP]^ ,** _-`a- 



Aizawa et al. (,**3a) (bcA bA dA e

O/# ! (Hyndman et al., +331 ; Lee et al., ,*+*)
f%F ^ ,** %^ 9."#gA hiA% / j@A9kl m' + km nY

op.:%CD qr s9t%>uv  w%x

E  y  z#"(  {

!|9}~.: (Fig. - and Table +)

;<}

 @Ai( s `a frock Sealing ( Cap  (++*-m) 



!"# $%&'() +** m

 "% s` #N $%F % /f +*)a. $%M$!A%&# /W+*-m ^ ,** _-%0."#

W"#R"#R

HPQ AHPQ B &! HPQ A %R

(..EE&'."#!%x!|9XJ:Aizawa et al. (,**3a)*# + ,- +323 ; Pellerin, ,**, ../
!j@A% /f (++*-m) " Sealing zoneJ  Fig. - }!E%E

(01234156  $%789 #:E CD%x9XO j@A(qr s%9# @AB EF0%(G% &0`aJ  ' Fig.

¡9¢.: (Fig. .) ++* (-m) %/

. %£%F¤9^ ,**(0T.:{j@A( + km _m/#Z[\HP] ¥ON¦)."# §¨ *$% -(T©ª/ Sealing zone  ."# ¬09­®&

opJ 

,** V./#

/ j@AB  ,** _F «^( Y%¯4°6±78

+ ²

 (ZablockiJ«,:#EF0( Sealing zone %-9 ³±³

et al., +31. ; Fitterman et al., +322 ; Sakuma et al., ,**2 ;0%¦)¥ON^ !:EF0( Sealing zone %F

Hurwitz et al., ,*+*) j@A( ,** 9´¨£

9$µ."z ¶-./." Sealing/^ &(`aJ."@/·0%¸#f¤¹N/W"#º1<^»¼®' H! %23(.:EF0½8Ai9,



254
Table +.

Relationship between SP proﬁle, resistivity structure and surface features.

Fig. -. Resistivity models and corresponding SP proﬁles for the Iwate, Iwaki, Nasu, Nantai, andNikko-Shirane volcanoes, respectively (Aizawa et al., ,**3a). Inverted triangles indicate MT
measurement sites. The horizontal axes are set as the projected distances along the MT surveylines. Surface geothermal activity is shown by blue arrows (solid : hot spring, dashed :fumarole). Pronounced SP minima on the ﬂanks of Type B (Fig. .) are marked by dashedvertical lines.

  Sealing zone ./0 B ,-1)234

5678BCDE& !"#$%& '()*+,- '9)*+,-1 :;)2<=>. 



Aizawa et al. (,**3a) 1./0 A!"N (Fig. ,) 1 ,3** OP)2<=QR

> STU./0 B BY,-ab]:;)2<=cdY efg
3mn

?@ A

FGH ,**/ ; IJK +313 %ELM)+,- o2p1./0 B q8r VW +322 TX ./0 A 

1Z[\]^_ ` ,-1)2<=hijkl@ (Lopez and Williams, +33- ; Finn etal., ,**+) s&1<= tuvwxyz3v{5|} )2<=~Y v{%&tuvwxyz3 & )2<=  wxyz3

' ih k k  B  Fig. - 8

& ./0 A ,-./0 B ,-\ {))2<=B  3@ {

255

Fig. .. Schematic model of a groundwater ﬂow within a volcanic ediﬁce. Solid and dashedarrows represent the ﬂow directions of liquid and vapor, respectively. The top of thehydrothermal system is sealed by a low permeability and electrically conductive clay-richlayer, which is shown as thick gray line in the ﬁgure. Conductive clay minerals (smectite)exist in the gray zone, whose bottom corresponds to the ,** isotherm. The hydrothermalzone below ,** within the volcanic ediﬁce is largely constrained to the volcano side of the
SP minimum. The hydrothermal zone is extensive beneath the ﬂat part of the SP proﬁle.
The two-phase zone may occur around the active conduit, but is not needed to explain theobservations. Note that the deep hydrothermal system, which may exist beneath thevolcanic basement, is not determined by Aizawa et al. ,**3a.



!"

 

#$%&'()*+9:*;34<=<4>

,-.#/012345678?@AB5C>@ Aizawa et al. (,**3b) #
DE F>G B4>H MT IJK3LMNOP/ 



QR . km G

ST@ , UV,-.3WX 

Fig. . 6Y7ZKO+6[\4] 6Q^/0_6  <`GaH!b^c^dec^548fgHhi/ jke_l4>mn

o3pq8fF3YrH (Fig. /) s_t uv (Fig. ,) DE (Fig. -a)

yIP#z}~_@o# wx@C - Heῌ . He s0,_R> Q^c^_hi/ j

C{|R> (Aizawa et al.,,**2a) +33233 6DE 8fgH/0



^c^5

5#]C456@a@ #>F_YrR>  ,**0 ; G ]3FR@5aH_ ,-.0 ,*+* ^c^54hi/ j_7>8 Sealing zone _/08f3 XHH

,-._

X@5C>@

R>/_t Aizawa et al.

(,*+*) #6 + z6\HA MT 

3 mῌ m&z3 < ^c^54¡¢(Hhi/ j_  +**+*** (m/day)0 
Aizawa et al. (,**3a) # £ QR +¤~ 1 6keHHX,-.

km 6¥¦§ 6¨ Sealing zone _©ªR>

_«¬H­®H {|R>H1¤~#

F3YrH % Fournier (+333) # 2* '¯°  6#

54%9´µ6¶7­~·¸¹6ºt{ H»g ^c^deo8  }~ .** ¼½ Brittle-±  7#²³

Fracture _hi/ j

567

256

Fig. /. Resistivity structure of Iwate volcano combined with seismicity and geodetic model(Aizawa et al., ,**3b). Black circles and white stars represent volcano-tectonic andlow-frequency earthquakes, respectively. Open rectangles show the temporal evolution of
the location of dike-shaped pressures source (Sato and Hamaguchi, ,**0). The numbers(ῌ ῍) shown at the center of each rectangle (dike) represent the order of the estimatedperiods.

Ductile transition zone 8 *+#,-9:;<=> Sealing zone (Fig. 0)  Sealing  ,** OP ;<= Sealing  .**FT. UL V W $?@A<B!CDE F8

MT

G1HI

?

J ( / km)  + +* (-m) .KLM1N :@A<B!Q8RS

XMYZ1[Heῌ .He -?M1

\ UL   ]^P J##W

/0I_ M / 8

8 , `. Sealing zone .abcLd2e f g!4_1 Fournier (+333)  ! "#$ %&'()

jkl mn$;<=;Aop%q : I *+#,-/0 +s&t1u

Aizawa et al. (,**3a) "#c.hi8lrSI
Fournier (+333) 

 .** Brittle-

vw_4_1  _.]^J.x'

Ductile transition zone

F.;<= Sealing  (y'z#)+{.*|1}+4,-L~}.m`8ly'z..WabI9 LI _ e8

 (Ohba et al., ,**2) __8 qJl

/H v

Sealing  *+#,-./012($ 134%ῌP M- Eab $14 V ^8P+.s- :e./8y'z4I%DA_2

 Reid (,**.) # Hurwitz et al. (,**1)

MT 0Gq (y'z..

``l (Ogawa et al., ,**+ ; Wannamaker et al., ,**3) LcYZ.~3.P8]^/0n.

MoE8lI%3$L4

P+s*!1 ^5.6#P+s/0

:' . MW9:/0*!1uvw_4617   8 ¡v

RS:9:q¤¥$LcYZP+!¦§o¨I V oE.%©; .`qI

1Y< $ ª«I^.s-.n¬*|1;

=>4_8vLI (Etheridge et al., +32- ;­®¯A;°B±?4_8]^²!.¢£@A

Jones, +321) - E.M + .9

_B³´%

eq1CIL:µ ;<= Sealing + Sealing #;<= Sealing  ]^#).

+ .9eq¢£ __8 +V¶e I6l (y'z+

³·8L (y.'z¸DL@¹1º 

E v»I_q Sibson,I6l Becken et al. (,**2)  San-Andreas+33, ; ¼h½ ,**- (y'z.8;Aomn

257

Fig. 0. Schematic model of groundwater ﬂow (Fournier, +333). Self sealing bysilica precipitation occur at about -1* to .**, which correspond to thebrittle-ductile transition zone. Note that the sealing zone by clay minerals(Aizawa et al., ,**3) occur at shallower level.

 !"#$  %&'()!*+,-.# /0123 4 5(!67 ,8 Sealing zone 9#:;*#)<=>?@A)BCD E,- DF GH
I1JKLMNO PQ*#RSTR=UV WX YZ[ K,-.# \]^I_ `ab cd ) efghij+D kl-  15(!6 m n
( oDp qr s*#tKKC uvwxy z{tK 23 uv|.}.#]~)5(!6
'tKD
ῐ

|7'#wK῏

1 ,+ Xbuv))K]7 p uv)'tKF -#wKY[qwp'] 9   % ¡¢ - 1 /0G!wuvL)"-tp *.uv4)£#¤¥'t'] ¦'tW§K]' ¨©ª1 % ¡$«)¬'t'] ] , %&­®¯ ° '$« ±($« |.²³´@1 µ¶)*·'] ¸¹uvºBKt»buv+,¼½ -uv¯+ ¥¼)'] ¦'tW§K]'῎ ῍ ῑ ῌAizawa, K. (,**.) A large self-potential anomaly and itschanges on the quiet Mt. Fuji, Japan. Geophys. Res. Lett.,-+, doi : L*/0+,+*.+*,3/,**.gl*+3.0,.
Aizawa, K., et al. (,**/) Hydrothermal system beneath
Mt. Fuji volcano inferred from magnetotellurics andelectric self-potential. Earth Planet. Sci. Lett., ,-/, -.-ῌ-//, doi : +*.+*+0/j.epsl.,**/.*-.*,-.
Aizawa, K. (,**2) Classiﬁcation of self-potential anomalies
on volcanoes and possible interpretations for their subsurface structure. J. Volcanol. Geotherm. Res., +1/, ,/-ῌ
,02, doi : +*.+*+0/j.jvolgeores.,**2.*-.*++.
Aizawa, K., Ogawa, Y., Hashimoto, T., Koyama, T.,
Kanda, W., Yamaya, Y., Mishina, M. and Kagiyama, T.
(,**2a) Shallow resistivity structure of Asama Volcano
and its implications for magma ascent process in the ,**.
eruption. J. Volcanol. Geotherm. Res., +1-, +0/ῌ+11, doi :+*.+*+0/j.jvolgeores.,**2.*+.*+0.
Aizawa, K., Uyeshima, M. and Nogami, K. (,**2b) Zeta
potential estimation of volcanic rocks on ++ island arctype volcanoes in Japan : Implication for the generationof local self-potential anomalies. J. Geophys. Res., ++-,
doi : B*,,*++*.+*,3/,**1jb**/*/2.
Aizawa, K., Ogawa, Y. and Ishido, T. (,**3a) Groundwaterﬂow and hydrothermal systems within volcanic ediﬁces :Delineation by electric self-potential and magnetotellurics.
J. Geophys. Res., ++., doi : B*+,*2+*.+*,3/,**2jb**/3+*.
Aizawa, K., Ogawa, Y., Mishina, M., Takahashi, K.,
Nagaoka, S., Takagi, N., Sakanaka, S. and Miura, T.
(,**3b) Structural controls on the +332 volcanic unrest

258

῎῏῍ῌ

at Iwate volcano : Relationship between a shallow, electrically resistive body and the possible ascent route ofmagmatic ﬂuid. J. Volcanol. Geotherm. Res., +21, +-+ῌ+-3, doi : +*.+*+0/j.jvolgeores.,**3.*2.**3.
Aizawa, K., Kanda, W., Ogawa, Y., Iguchi, M., Yokoo, A.,
Yakiwara, H. and Sugano, T. (,*+*) Temporal Changes
in Electrical Resistivity at Sakurajima Volcano from
Continuous Magnetotelluric Observations. J. Volcanol.
Geotherm. Res, doi : +*.+*+0/j.jvolgeores.,*+*.++.**-.
(in press).
Becken, M., Ritter, O., Park, S.K., Bedrosian, P.A.,
Weckmann, U. and Weber, M. (,**2) A deep crustal
ﬂuid channel into the San Andreas Fault System near
Parkﬁeld, California. Geophys. J. Int., +1-, 1+2ῌ1-,, doi :+*.++++/j.+-0/-,.0X.,**2.*-1/..x.
Etheridge, M.A., Wall, V. J. and Vernon, R.H. (+32-) The
role of the ﬂuid phase during regional metamorphism anddeformation. Journal of Metamorphic Geology, +, ,*/ῌ,,0.
Finn, C.A., Sisson, T.W. and Deszcz-Pan, M. (,**+)
Aerogeophysical measurements of collapse-prone hydrothermally altered zones at Mount Rainier volcano. Nature,.*3, 0**ῌ0*-.
Fitterman, D.V., Stanley, W.D. and Bisdorf, R. J. (+322)
Electrical structure of Newberry volcano, Oregon. J.
Geophy. Res., 3-, +*++3ῌ+*+-..
Fournier, R.O. (+333) Hydrothermal processes related to
movement of ﬂuid from plastic into brittle rock in themagmatic-epithermal environment. Economic Geology,
3., ++3-ῌ+,++.
Gaillard, F. and Marziano, G.I. (,**/) Electrical conductivity of magma in the course of crystallization controlled
by their residual liquid composition. J. Geophys. Res.,++*, doi : +*.+*,3/,**.jb**-,2,.
Hase, H., Ishido, T., Takakura, S., Hashimoto, T., Sato, K.
and Tanaka, Y. (,**-) Zeta potential measurement of
volcanic rocks from Aso caldera. Geophys. Res. Lett., -*,,,+*, doi : +*.+*,3/,**-GL*+203..
Hurwitz, S., Christiansen, L.B. and Hsieh, P.A. (,**1)
Hydrothermal ﬂuid ﬂow and deformation in large calderas : Inferences from numerical simulations. J. Geophys.
Res., ++,, doi : B*,,*0+*.+*,3/,**0jb**.023.
Hurwitz, S., Farrar, C.D. and Williams, C.F., (,*+*) The
thermal regime in the resurgent dome of Long Valley
Caldera, California : Inferences from precision temperature logs in deep wells, J. Volcanol. Geotherm. Res., doi :+*.+*+0/j.jvolgeores.,*+*.*2.*,-. (in press).
Hyndman, R.D., Yamano, M. and Oleskevich, D.A. (+331)
The seismogenic zone of subduction thrust faults. Isl.
Arc., 0, ,..ῌ,0*.
Ishido, T. and Mizutani, H. (+32+) Experimental andtheoretical basis of electrokinetic phenomena in rockwater systems and its applications to geophysics. J.
Geophy. Res., 20, +10-ῌ+11/.
Ishido, T. (,**.) Electrokinetic mechanism for the “W”-shaped self-potential proﬁle on volcanoes. Geophys. Res.
Lett., -+, doi : L+/0+0+*.+*,3/,**.gl*,*.*3.

Jones, A.G. (+321) MT and reﬂection - an essential combination. Geophys. J. Int., 23, 1ῌ+1.
Kagiyama, T., Utada, H. and Yamamoto, T. (+333) Magma
ascent beneath Unzen Volcano, SW Japan, deduced fromthe electrical resistivity structure. J. Volcanol. Geotherm.
Res., 23, -/ῌ.,.
Lee, J.O., Kang, I.M. and Cho, W. J. (,*+*) Smectite
alteration and its inﬂuence on the barrier properties ofsmectite clay for a repository. Applied Clay Science, .1,
33ῌ+*., doi : +*.+*+0/j.clay.,**2.+*.**1.
Lopez, D.L. and Williams, S.N. (+33-) Catastrophic volcanic collapse - relation to hydrothermal processes. Science, ,0*, +13.ῌ+130.
Michel, S. and Zlotnicki, J. (+332) Self-potential and magnetic surveying of La Fournaise volcano (Reunion
Island) : Correlations with faulting, ﬂuid circulation, anderuption. J. Geophys. Res., +*-, +12./ῌ+12/1.
Morgan, F.D., Williams, E.R. and Madden, T.R. (+323)
Streaming potential properties of Westerly granite withapplications. J. Geophys. Res, 3., +,..3ῌ+,.0+.
Ogawa, Y. and Uchida, T. (+330) A two-dimensional
magnetotelluric inversion assuming Gaussian static shift.
Geophys. J. Int., +,0, 03ῌ10.
Ogawa, Y., et al. (,**+) Magnetotelluric imaging of ﬂuids
in intraplate earthquake zones, NE Japan back arc.
Geophys. Res. Lett., ,2, -1.+ῌ-1...
Ohba, T., Hirabayashi, J. and Nogami, K. (,**2) Temporal changes in the chemistry of lake water within Yugama
Crater, Kusatsu-Shirane Volcano, Japan : Implications
for the evolution of the magmatic hydrothermal system.
J. Volcanol. Geotherm. Res., +12, +-+ῌ+.., doi : +*.+*+0/
j.jvolgeores.,**2.*0.*+/.
Pellerin, L. (,**,) Applications of electrical and electromagnetic methods for environmental and geotechnicalinvestigations. Surveys in Geophysics, ,-, +*+ῌ+-,.
Reid, M.E. (,**.) Massive collapse of volcano ediﬁces
triggered by hydrothermal pressurization. Geology, -,,-1-ῌ-10, doi : +*.++-*/g*,-**.+.
Revil, A., Pezard, P.A. and Glover, P.W.J. (+333) Streaming potential in porous media +. Theory of the zeta
potential, J. Geophys. Res., +*., ,**,+ῌ,**-+.
Revil, A., et al. (,**2) Inner structure of La Fossa di
Vulcano (Vulcano Island, southern Tyrrhenian Sea, Italy)
revealed by high-resolution electric resistivity tomography coupled with self-potential, temperature, and CO,
di#use degassing measurements. J. Geophys. Res., ++-,
doi : B*1,*1+*.+*,3/,**1jb**/-3..
Sakuma, S., Kajiwara, T., Nakada, S., Uto, K. and Shimizu,
H. (,**2) Drilling and logging results of USDP-. Penetration into the volcanic conduit of Unzen Volcano,Japan. J. Volcanol. Geotherm. Res., +1/, +ῌ+,, doi :+*.+*+0/j.jvolgeores.,**2.*-.*-3.
Sasaki, Y. (,**.) Three-dimensional inversion of staticshifted magnetotelluric data. Earth Planets Space, /0,,-3ῌ,.2.
Sato, M. and Hamaguchi, H. (,**0) Weak long-lived
ground deformation related to Iwate volcanism revealed

by Bayesian decomposition of strain, tilt and positioning
data. J. Volcanol. Geotherm. Res., +//, ,..ῌ,0,, doi :+*.+*+0/j.jvolgeores.,**0.*-.*-+.
Sibson, R.H. (+33,) Implications of fault-valve behavior
for rupture nucleation and recurrence. Tectonophysics,,++, ,2-ῌ,3-.
Sill, W.R. (+32-) Self-potential modeling from primary
ﬂows. Geophysics, .2, 10ῌ20.
Tosha, T., Matsushima, N. and Ishido, T. (,**-) Zeta
potential measured for an intact granite sample at temperatures to ,** degrees C. Geophys. Res. Lett., -*, doi :+,3/+*.+*,3/,**,gl*+00*2.
Wannamaker, P.E., Caldwell, T.G., Jiracek, G.R., Maris,
V., Hill, G. J., Ogawa, Y., Bibby, H.M., Bennie, S.L. andHeise, W. (,**3) Fluid and deformation regime of anadvancing subduction system at Marlborough, New Zealand. Nature, .0*, 1---U13*, doi : +*.+*-2/nature*2,*..
Zablocki, C. J., Tilling, R.I., Peterson, D.W. and Christiansen,
R.L (+31.) : A deep research drill hole at the summit ofan active volcano, Kilauea, Hawaii., Geophys. Res. Lett.,+, -,-ῌ-,0.
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