High-Resolution Seismic Reflection Survey Oguro River Seismic Line in the Ina Valley Fault Zone, Central Japan: Data Acquisition and Processing

Μέγεθος: px

Εμφάνιση ξεκινά από τη σελίδα:

Download "High-Resolution Seismic Reflection Survey Oguro River Seismic Line in the Ina Valley Fault Zone, Central Japan: Data Acquisition and Processing"

Ἰσμήνη Λαγός
5 χρόνια πριν
Προβολές:

1 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. 2,,**1 pp. +-,- : + +, -. / * ++ +, / +0 +, : - :. / : 0 : : +* ++ +, : +- : +. : +/ : +0 : High-Resolution Seismic Reflection Survey Oguro River Seismic Line in the Ina Valley Fault Zone, Central Japan: Data Acquisition and Processing Shinsuke Okada +, Yasutaka Ikeda +, Shin Oda,, Tomoo Echigo -, Shigeru Toda., Norimasa Suzuki /, Youhei Kawai 0, Hajime Kato 1, Hiroshi Sato 2, Haruo Kimura 2, Masayoshi Tajikara 3, Tatsuya Ishiyama +*, Toshifumi Imaizumi ++, Kyoko Kagohara +,, Nobuhisa Matsuta +-, Takuma Uchida +., Tomoki Uno +/ and Tomonori Kawamura +0 + Graduate School of Science, The University of Tokyo,, Graduate School of Science, The University of Tokyo (Now at Idemitsu Kosan Co., Ltd.), - Graduate School of Science, The University of Tokyo (Now at Geo-Research Institute),. Aichi University of Education, / Aichi University of Education (Now at Toyota Municipal Wakazono junior high school), 0 Aichi University of Education (Now at Toyota Auto Body Co., Ltd.), 1 Faculty of Education and Human Sciences, University of Yamanashi, 2 Earthquake Research Institute, The University of Tokyo, 3 Earthquake Research Institute, The University of Tokyo (Now at Japan Atomic Energy Agency), +* Active Fault Research Center, National Institute of Advanced Industrial Science and Technology, ++ Graduate School of Science, Tohoku University, +, Interdisciplinary Graduate School of Medical and Engineering, University of Yamanashi (Now at Graduate School of Science, Tohoku University), +- Earthquake Research Institute, The University of Tokyo (Now at National Taiwan University), +. Graduate School of Science and Technology, Chiba University (Now at Earth Science Department, Keio Senior High School), +/ Graduate School of Science and Technology, Chiba University (Now at Kimoto co., Ltd.), +0 Earthquake Research Institute, The University of Tokyo (Now at JGI Inc.) Abstract Ina Valley Fault Zone consists mainly of two subparallel fault strands: the boundary fault and the frontal fault. The boundary fault is located at the foot of the Kiso range. The frontal fault is located several kilometers east of the boundary fault. Both faults are thrust faults with high rates of horizontal shortening. To reveal the subsurface structure of and relationship between these two faults, we carried out a high-resolution seismic reflection survey along the Oguro River in the s_okada@eps.s.u-tokyo.ac.jp ++- **

northern Ina Valley. The source used in the survey was a mini-vibrator (T-+/***). The source and receiver spacing was +* m, with,.*-ch geophones used for recording.

2 northern Ina Valley. The source used in the survey was a mini-vibrator (T-+/***). The source and receiver spacing was +* m, with,.*-ch geophones used for recording. The seismic section after careful data processing shows that the boundary fault dips west at a fairly low angle and the frontal fault is likely to converge on the boundary fault at depth. Westward dip of basin-fill sediments becomes steeper with increasing depth, indicating that the basin-fill sediments are syntectonic. Key words: Ina valley fault zone, high-resolution seismic reflection profiling, subsurface structure, boundary fault, frontal fault +, ;,**, Fig. + km +* km Fig. +. Relief map of Ina valley. Black solid lines, active faults (after Ikeda et al.,,**,); gray solid lines, seismic lines; gray dashed lines, gravity survey lines. 14

I J ± +N e9 ^( }~ %`)* +N ῌ +321 ;,**,! "#$% e9! S fuv" Fig. +!& )* [ KL k RF '"[ i(% )2 '%( )* +,-./0123 4 RF +330 ; +330!& 56 789 : 6;< *.1 mmῌyr Ikeda and Yone- +FRS e9!

$SZRF '"[\]^%RF %RF [ +330 ; +330! Ikeda and Yonekura, +320 ; ῌ +321 ; = ( 2, H e9, >?@ +33+ ; AB +33/!& 6 '%_ %RFH Z`& C' _` +33,! 6 abhcde9 fge Fig.$

3 I J ± +N e9 ^( }~ %`)* +N ῌ +321 ;,**,! "#$% e9! S fuv" Fig. +!& )* [ KL k RF '"[ i(% )2 '%( )* +,-./ RF +330 ; +330!& : 6;< *.1 mmῌyr Ikeda and Yone- +FRS e9! [ %R+ kura, +320 ; ῌ +321 ; = >?@ +33+ ; A KLHk [ i(%rf B +33/! "C% D<EFG 6HF& +330 ; +330!& I J6KLH M N OP% Q R+ I J +FR6 S 3`, )* , STU <EHV.WX45 " C% % e9[ 0..Y+.0 mmῌyr! SZRF '"[\]^%RF %RF [ +330 ; +330! Ikeda and Yonekura, +320 ; ῌ +321 ; = ( 2, H e9, >?@ +33+ ; AB +33/!& 6 '%_ %RFH Z`& C' _` +33,! 6 abhcde9 fge Fig. I J +N )* " w j6 k lmh no 2 `i e9,**. +* H )* pzrqrst fuv w x FRª«`& w C 2 yz F "{ `& & +! I hi Fig.,. Fig. -. Seismic line (Oguro River,**.) of this study. Distribution of number of folds along a CMP stacking line. ² 15 ²

4 , 0.. km Fig., - +, - -* /* m RP: Reciever Point RP. +**+,** m VP : Vibrate Point VP. *32+ VP. +***,* RP. +**+ +,.* CMP Fig. - RP. +*3. CMP. +21 RP. +,10 CMP. /-+ Fig... Example of shot gather at RP +,,.. Table +. Data acquisition parameters for the Oguro River,**. seismic line. - IVI, T-+/***; * m +* Hz + m GDAPS-., msec - sec,**,,**,,.* ch +2* ch, 0* ch Fig.. Table +. Super X-C Fig. / 16

5 Fig. /. Flow chart of data-processing. Table,. Processing parameters for CMP Oguro River,**. seismic data. Table, fold stacking line Fig., CMP CMP / m +,* P +., -** msec AGC,.* msec,,,*** msec,, msec iras P Fig. 0 NMO CMP CMP NMO NMO Fig. 1 CMP NMO NMO CMP /* 17

6 Fig. 0. Surface velocity structure determined by time-term analysis. (a) Time-terms. (b) Velocities of second layer. (c) Topography and geometry of surface low velocity layer. +* msec NMO CMP +,* CMP CMP Fig. - +* +/ 2* 3* Hz F-X 1 1* /** msec CMP +** /** 1/* 3** +,** Fig. 2 Fig. 1 Fig. 3 / Fig. 1, Fig. 2, Fig. 3 18

7 Fig. 1. Velocity structure along the Seismic line (Oguro River,**.). CMP /** CMP /** CMP /** CMP /** Fig. 1 Fig. 3 Fig. +* CMP 10* +** m CMP 3,* /** m CMP.+*.** m CMP /-* CMP 02* /** m CMP /-+ CMP /-+ CMP 02* /** m, CMP 10* +** m CMP 3,* /** m CMP 02*.1* m * m CMP -,* /* m CMP /2*.-* m CMP 20* 21* m CMP,0* CMP -/* -** m CMP,,* //* m -** m /** m CMP,0*./* /* m -** m CMP + +**.** m CMP,0*./* * m -** m fault-bend fold CMP

8 Fig. 2. Time section after migration. ῑ ῐ ῌ 20 ῌ

9 Fig. 3. Depth converted seismic section. 21

10 Fig. +*. Geologic interpretation of the depth converted seismic section. ῑ ῐ ῌ 22 ῌ

11 +/ +1 B +/-**-** : * Ikeda, Y. and Yonekura, N., +320, Determination of late Quqternary rates of net slip on two major fault zones in central Japan, Bull. Dept. Geogr., Univ. Tokyo, +2, , : flake tectonics / ++1 +,* ,**,,/. p p. +33/ / No.,,,,.0 1* p / +** +*/. Received November +.,,**0 Accepted March +,,,**1 23

Σχετικά έγγραφα

High-resolution seismic reflection survey across the Western Boundary Fault Zone of the Nagano Basin, Central Japan: Data acquisition and processing

Bull. Earthq. Res. Inst. Univ. Tokyo Vol. 2+,**0 pp. +1++2* : + * +, -. / 0 1 1 2 3 +, : -. / 0 1 2 : 3 +* : +* High-resolution seismic reflection survey across the Western Boundary Fault Zone of the Nagano