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

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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 haveinvestigated 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 andthe distribution and the movement of fluid in the crust.
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67879:!+,-./0123-4156-.1-7891-7:;!
Keywords: dense seismic array, Kinki district, micro-earthquake, crustal structure,geofluid!
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Fig. 1 Distribution of the seismic stations. TheYellow and Red circles show the temporal stations
installed by this study. Others are permanentstations.
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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.

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Fig. 3 Distribution of the type of stress field at thenorthern Kinki district. Green circles mean theFig. 4 Distribution of S-wave reflector in thereverse fault type field; red are strike-slip type;lower crust. The reflector exists within the areagray means “not specified”. (Aoki , 2012)

shown by the purple mesh. (Aoki, 2013)

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