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183
Bull. Earthq. Res. Inst.
Univ. Tokyo
Vol. pp.
* e-mail : [email protected]
M
Earthquake Research Institute, University of Tokyo
Association for Earthquake Disaster Prevention
The Earthquake Research Committee of the Headquarters of Earthquake Research and Promo-
tion estimated the probability of an earthquake of magnitude around . occurring during the next
years as . This is based on five earthquakes that occurred in the southern Kanto region (i.e.,
the Meiji-Tokyo earthquake, the and Ibaraki-ken Nanbu earthquakes, the
Uraga-channel earthquake and the Chiba-ken Toho-Oki earthquake). However, it has been
revealed that the Kanto region is situated on complicated tectonic conditions due to subduction of
the Philippine Sea Plate and the Pacific Plate beneath the continental plate, and that various types
of earthquake occur. Therefore, it is necessary to classify these earthquakes into interplate and slab
earthquakes, and to estimate recurrence intervals. In this paper, at the outset of such studies, we
review previous studies on three earthquakes (the Ibaraki-ken Nanbu earthquake, the
Uraga-channel earthquake and the Chiba-ken Toho-Oki earthquake) that occurred after the
beginning of the Taisho era ( ) and describe the collected data.
: M earthquakes, the Ibaraki-ken Nanbu Earthquake, the Uraga-channel
Earthquake, the Chiba-ken Toho-Oki Earthquake, the southern Kanto region
km
*
Takeo Ishibe *, Akihito Nishiyama , Kenji Satake and Kunihiko Shimazaki
Abstract
Key words
The Ibaraki-ken Nanbu Earthquake, the Uraga-channel
Earthquake and the Chiba-ken Toho-Oki Earthquake
M
Review of Previous Studies on M -class Earthquakes
that Occurred in the Southern Kanto Region and Data
Collection
+
,
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184
Fig. . Five earthquakes (i.e., the Meiji-Tokyo earthquake, the Ibaraki-ken Nanbu earthquake, the
Ibaraki-ken Nanbu (Ryugasaki) earthquake, the Uraga-channel earthquake and the Chiba-ken
Toho-Oki earthquake) used to estimate the occurrence probability of ‘other M class earthquakes that have
occurred in the southern Kanto region’. The epicenter and magnitude of the Chiba-ken Toho-Oki
earthquake are based on the Japan Meteorological Agency (JMA), and others are based on Utsu ( ).
M
b a a, b a,
b, b
b, d
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M . ;
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Fig. . Hypocenter and focal mechanism of the Ibaraki-ken Nanbu earthquake C : Central
Meteorological Observatory ( ), O : Omori ( a, g), Ushi : Ushiyama ( c), K : Katsumata
( a, b), I : Ishibashi ( a, b, b), Utsu : Utsu ( ), Usa : Usami ( ) . Parenthetic
number (in km) or character (s : shallow ; ? : unknown) indicates hypocentral depth.
a
.
km
mm
B Omori g
a A Ushiyama c . .
. S-P
E N
Ushiyama c km Omori g S-P
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b . a .
a, b Ushiyama c
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188
Table . Seismological reports on the Ibaraki-ken
Nanbu earthquake by meteorological observatories
from Ushiyama ( a).
Fig. . Seismograms of the Ibaraki-ken Nanbu
earthquake recorded by the strong motion seismo-
graph at (a) Hongo, and (b) Hitotsubashi (from
Omori, g).
a Yasuda b
. E, . N
. E . N M km
. S E
. E, . N M . km
km b, d
a
S-P a a, b, c
. .
S-P Omori . . S-P
g E, N km
. S-P
km
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+3,+
+3,, +3,, -
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.
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Table . Documents on the Ibaraki-ken Nanbu earthquake.
PAC
km
a, b S-P
E, N, km
M . M c
.
M . b . Nm Mw .
. E, . N a, b, c km
M PHS PAC
PAC PHS
PHS
. E, .
N M .
GME
a, b, c
. Nm Mw .
b a, b, ,
c a, b, GME
PHS PAC
km
a
PHS PAC
+2
+2
/ +3,+
+* +33*
+301
+32/
+31/ +31/ ,***
+.* *- - -0 *3 . +* ,
0 1 ,
1 + +313 ,+ +-, 13 /.
1 * +31/ . / +* 0 .
+.* , -0 * +31/ +31/ +31/ /-
+3,- ,
+3,+ +3,, ,**+
.
,**- +313 +.* , -0 *
1 *
,***
,
+32/
+31/ +31/ +31/ / +3,+
/ 0 +* 0 .
+ ,22
13 -.
, +31/ +31/ ,*** ,**-
+31/ ,**- ,**.
0* 1/ +, +0
,, +3,,
+3,+
, ,
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M
Fig. . Seismic intensity distribution map of the Ibaraki-ken Nanbu earthquake by (a) Omori ( h),
(b) Kanbayashi and Katsumata ( ), (c) Utsu ( ) and (d) Usami ( ).
Central Meteorological Observatory
a
b, c, e Omori h a,
b a, b, c
a Yasuda b
a Ushiyama c Omori h c
:
. E, . N
M
c a Nakamura b
M . ;
1
. +3,+ +3,,
+31/ +323 ,**-
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+31/ +31/ +31/ +31/ +313
,**-
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+3,+ /
+3,, +3,, +3,, +3,, +3,, . ,0
+31/ +323 ,**- +* ++ +*
. ++ +-3 3 -/ .
0 +3,,
1
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+ ,
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- +
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M
Fig. . Hypocenter [C : Central Meteorological Observatory ( c), N : Nakamura ( a, b), O : Omori
( h), K : Katsumata ( a, b), I : Ishibashi ( c), I : Ishibashi ( a, b) Utsu : Utsu ( ), Usa :
Usami ( )] and focal mechanism [Ishibashi ( d)] of the Uraga-channel earthquake. Parenthetic
number (in km) or character (s : shallow ; ? : unknown) indicates hypocentral depth.
b c mm sec
mm sec
. mm sec
Omori h
km
mm sec
C d .
km
E,
N km
a Nakamura b
.
.
e km b
.
km . E, . N M .
+ ,
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,
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1
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M
Fig. . Seismograms of the Uraga-channel earthquake recorded by strong motion
seismographs at (a) Hongo, and (b) Hitotsubashi (from Omori, h).
a, b a, b S-P
M . M .
N, km Omori
h
/ E, . N km
. c
S-P
P
Vp Vs
E, N km
. d
. . P P
E, a,
N km b a, b M
. E, . N
a, b . M .
. . . PHS PAC
. . S-P
E, . E, . N, M .
S-P km km
km M .
a, b PAC
1
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+3,,
+31. +31. +31/ +31/
0 3 0 2
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+31-
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+31. +31- +31.
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/
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1* 3* 1
. 3* +33, , , / 1
+31/ +31/
+3,+
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196
Fig. . Recent seismicity around the Uraga channel from the unified Japan Meteorological
Agency catalog (October, to May ). The blue star indicates hypocenter of the
Uraga-channel earthquake from Ishibashi ( a, b). The open star indicates
epicenter of the Uraga-channel earthquake from Utsu ( ).
1
+331 ,**2
+3,, +31/ +31/
+3,, +313
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M
Table . Documents on the Uraga-channel earthquake.
Fig. . Seismic intensity distribution map of the Uraga-channel earthquake by (a) Omori
( h), (b) Kanbayashi and Katsumata ( ), (c) Utsu ( ) and (d) Usami ( ).
c Omori h
c Omori h
1
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a
M-T
Centroid moment tensor Dzie-
wonski Nabelek
b
. dynecm . km
CMT . dynecm . km Nabelek
M km
km . km Takeo
;
,
,
, . E . N
; km M .
. km km .
. . . m
c Sato and Mat-
su’ura
; ;
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et al.,
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Fig. . Focal mechanisms of the Chiba-ken Toho-Oki earthquake from (a) Japan
Meteorological Agency ( a), (b) Kawakatsu ( ), (c) Yamada ( ), (d) Yamada and
Sato ( ), (e) Okada and Kasahara ( ) and (f) Ishibe and Tsuruoka ( ).
PHS
km
PHS
A : Fukuyama
km B :
km C :
km
A PHS
B PAC C
PHS
C
d
Qs
3 +321
+322 +322 +322
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direction (hypocentral depth, km), B : reverse fault-
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M
Fig. . Focal mechanisms of earthquakes occurring
eastern o shore of the Chiba prefecture and classifica-
type with compression axis in northeast-southwest
type with compression axis in east-west direction
(hypocentral depth, km), C : low angle reverse
or northern northwest-southern southeast direction
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Table . Documents on the Chiba-ken Toho-Oki earthquake.
M .
Miko-
cm shiba
cm Okada and Kasahara,
a
a b ; ; ;
PHS PHS a
b
M . M
et al.
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Fig. . Seismic intensity distribution map of the Chiba-ken Toho-Oki earthquake by (a) Japan
Meteorological Agency ( a), (b) Usami ( ), (c) Harukawa ( ) and (d) Ara ( ).
; ; ;
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Ansei Edo earthquake, , B , doi :
H., , A high quality digital network for microearth-
quakes and ground tilt observations in the Kanto-
. Tokai area, Japan. , .
Bakun, W.H., , Magnitude and location of historical
earthquakes in Japan and implications for the .
. / JB .
D .
.
Central Meteorological Observatory, a, Some notable
earthquakes occurred near Japan and the distant earth- .
quakes observed in Japan in ,
, .
Central Meteorological Observatory, b, Seismological .
Observation in Tokyo (Jan.-April, ),
, .
.
.
.
. .
pp. a,
.
pp. b, ERTS
. No. .
c, a,
.
.
. b, S-P
Dziewonski, A.M., Chou, T.A.-. and Woodhouse, J. H., , .
Determination of earthquake source parameters from c, S-P
waveform data for studies of global and regional seis- .
micity, , . d,
.
.
S .
M
Green
. .
JUNEC
.
Fukuyama E., , Inversion for the Rupture Details of the P .
East Chiba Earthquake, Japan, Using a Fault
Model Based on the Distribution of Relocated After- .
shocks, , .
.
. a,
: .
B . b,
.
.
. .
Hamada, K., Ohtake, M., Okada, Y., Matsumura, S. and Sato,
J. Geophys. Res.,
Earthquake Predict. Res.,
Seism, Bull. Cent.Met. Obs., Japan,
Seism, Bull.Cent. Met. Obs., Japan,
b
J. Geophys. Res.,
J. Geophys. Res.,
, No.
, No.
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pp. pp.
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. Mikoshiba T., M. Miyamoto, S. Kinoshita, , DIGITIZED
DATA ON NRCDP STRONG-MOTION EARTHQUAKE
RECORDS ( ) December , EAST OFF CHIBA
PREFECTURE EARTHQUAKE
. .
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. B I .
b,
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.
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a, III
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. parameters from inversion of body waves, Ph. D. The-
b sis,
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Nakajima, J. and A. Hasegawa, , Cause of M intra-
. slab earthquakes beneath the Tokyo metropolitan area,
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. Takeo, M., , An inversion method to analyze the rupture
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, . , .
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, , , .
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Appendix A. Destructive earthquake around Inba-numa of the Chiba prefecture
on , December from Ushiyama ( a).
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B
a
Appendix B. Destructive earthquake in the Tokyo Metropolitan area
on , Dec., from Omori ( a).
C b
Appendix C. Destructive earthquake in the Tokyo Metropolitan area
from Omori ( b).
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