$012#345(Aoki , 2012) Fig. 4 Distribution of S-wave reflector in the lower crust. The reflector...
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!"#$%&’()*+#,-./#$012#345 The Seismicity and the Crustal Structure of the Northern Kinki District Investigated by the Dense Seismic Array Observations !" #$%& ’$(")* Hiroshi KATAO, Tsutomu MIURA and Yoshihisa IIO Synopsis In the northern Kinki district, we have done seismic observations using the dense seismic array stations since 2008. Total 150 temporal and permanent stations are used, and the average interval between the stations is about 5km. Using these data, we have investigated the seismic velocity structure, the shape and distribution of the reflector in the lower crust, the Moho and the PHS plate, the focal mechanisms and the stress field etc. The results of these observations and other geophysical data exhibit and characterize the strong contrast between the Tamba region and the Oumi Basin region. Difference of these two region caused to the geometry of subducting PHS plate beneath this area and the distribution and the movement of fluid in the crust. 67879: +,-./0123-4156-.1-7891-7:; Keywords: dense seismic array, Kinki district, micro-earthquake, crustal structure, geofluid ;< =>?’ 23-4<=><?$@AB-CDEF<=GH IFJ=KLMNO><P4QRSTUVWXYZ -[\1]^_Q56-.‘ab‘cd-[efUg h>-.‘a\Ji_Q\jkl]^_efUb1 mnQ‘aobDpqrstuvbwxylLz1 {|}>rsQ~Q{TUfUx ylUg2QLl1 2003 -.‘a> blUylUC!"1 2005aKg 23-4Q\‘Bbq1]>‘Q _™bz]^_d-.‘a\1Q Llf¡z¢v>d£d>xyU C!"12002Kb1-.‘a>/¥Ql\ƒ §¤'“«ldghy¡e>‹q>›fiQMz flb–²ylU-‡=>:;b1@AB- >]^‘a>·¥O>‘arsQDpq¶tl U>xyUC!"12005bKb1O>•‚ >ukQ\„”d-89Q»TU…‰b¿ef Ug21`/0´>ˆ˜QMz1¯[ b˘˙¨20km ˚>¸o-./0´e˝˛ ylUgt“tdbx1ˇ—-.>/¥fi‚>u k-7ˇ'd•oeUukQ\1xQ+ ,d-./0¿bfUg @< !"#$%& ›fi-.w›fi˛e\1 2008 Mz>ƪJ>_LØ/0$› fiŒ>ºtl1VWXYZ“x@AB-Q“ l45>/0l-./0«lUg xQ20104æ“x\Æ-.NBw>u 京都大学防災研究所年報 第 56 号 B 平成 25 年 6 月 Annuals of Disas. Prev. Res. Inst., Kyoto Univ., No. 56 B, 2013 ― 167 ―
Transcript of $012#345(Aoki , 2012) Fig. 4 Distribution of S-wave reflector in the lower crust. The reflector...
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!"#$%&'()*+#,-./#$012#345!!
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The Seismicity and the Crustal Structure of the Northern Kinki District
Investigated by the Dense Seismic Array Observations
!
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Hiroshi KATAO, Tsutomu MIURA and Yoshihisa IIO
!
Synopsis!
In the northern Kinki district, we have done seismic observations using the dense
seismic array stations since 2008. Total 150 temporal and permanent stations are used,
and the average interval between the stations is about 5km. Using these data, we have
investigated the seismic velocity structure, the shape and distribution of the reflector in
the lower crust, the Moho and the PHS plate, the focal mechanisms and the stress field
etc. The results of these observations and other geophysical data exhibit and characterize
the strong contrast between the Tamba region and the Oumi Basin region. Difference of
these two region caused to the geometry of subducting PHS plate beneath this area and
the distribution and the movement of fluid in the crust.
!
67879:!+,-./0123-4156-.1-7891-7:;!
Keywords: dense seismic array, Kinki district, micro-earthquake, crustal structure,
geofluid
!
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京都大学防災研究所年報 第 56 号 B 平成 25 年 6 月
Annuals of Disas. Prev. Res. Inst., Kyoto Univ., No. 56 B, 2013
― 167 ―
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Fig. 1 Distribution of the seismic stations. The
Yellow and Red circles show the temporal stations
installed by this study. Others are permanent
stations.
Fig. 2 (Upper) Results of tomography. Red means
lower velocity, and blue means higher. (Middle)
1-D velocity structure derived by JHD analyses
(Lower) Station corrections for the P and S travel
times derived by JHD analyses.
― 168 ―
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Fig. 3 Distribution of the type of stress field at the
northern Kinki district. Green circles mean the
reverse fault type field; red are strike-slip type;
gray means “not specified”. (Aoki , 2012)
Fig. 4 Distribution of S-wave reflector in the
lower crust. The reflector exists within the area
shown by the purple mesh. (Aoki, 2013)
Fig. 5 Cross sections of the receiver function
images along the EW line at the northern Kinki
district. (Aoki, 2013)
― 169 ―
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Fig. 7 Seismicity of the Tamba and Oumi area
during 1997 – 2012. (Upper) Epicenter distribution
(Middle) Time space distribution (Lower) EW
cross section
Fig. 6 Two dimensional resistivity structure across
the Hanaori fault obtained by inversion from TM
mode data (Yoshimura et al., 2005)
― 170 ―
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Fig. 9 schematic structure model across the Tamba
and Oumi region
― 171 ―
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