Title 稠密地震観測による近畿地方北部の地震活動と地殻構造

Author(s) 片尾, 浩; 三浦, 勉; 飯尾, 能久

Citation 京都大学防災研究所年報. B = Disaster Prevention ResearchInstitute Annuals. B (2013), 56(B): 167-172

Issue Date 2013-09

URL http://hdl.handle.net/2433/181552

Right

Type Departmental Bulletin Paper

Textversion publisher

Kyoto University

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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

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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.

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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

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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

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Fig. 6 Two dimensional resistivity structure across

the Hanaori fault obtained by inversion from TM

mode data (Yoshimura et al., 2005)

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Fig. 9 schematic structure model across the Tamba

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