high-resolution seismic reflection profiling across the … masami togo+*, takaya iwasaki++,...

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腖腏腚腘 腐腎腊腍腚腄腉腗腘腝腒腞腛腕腙腑: 腌腀腋腓 腜腇腔腟腈腅腃腆 腳膥膰臆腽 +*膟膢腊臃 ,腲膒膄膳 -腹腆膢腣 .腫膢 /腯膬 0腏膚 11腋膥膚膎 2腜膩膋膾 2膭膻腯腻 3膤腡膍膱 +*腙腸腛腵 ++膴膢 +膇膗膈膆 ++腒膖膝膧 +,膏腘腭膕 +-腌膑 +.膐腐30膯膁膶膞膉膛腴腅腈腀腇 +膤腟膙腕膞膉腧腞膅,膤腟膙腕膙腕腎臁腕腦腧腞腑-腺臀膙腕腠腍膊腗腑腕膲 腪腶: 膤膷膙腕膙腕 腎臁腕腦腧腞腑.膤腟膙腕膞膉腧腞膅 腪腶: 腟膣膙腕膙腕腎腬腕腧腞腑/腉膝腠腍膙腕0腟膣膙 腕膙腕腎臁腕腦腧腞腑1腙膃膙腕腬腕膲2膐膿膙腕臁腕膲3腺腥膙腕腠腍腕膲+*膶膌膙腕++腟膙腕膙腕腎臁腕腦腧腞腑 腪腶: 腱臂膘臈膙腕+,膐膿膙腕膀膓腑腕膔腰腧腞腑 腪腶: 膞腝腑腕 膔腰腧腞膅+-膦臅臇腔膫臄腓膮腾腢膜 腪腶: 膪膸腩腼臅腧腞腓膮腚腮+.膞腝腑腕膔腰 腧腞膅 High-resolution seismic reflection profiling across the Senya fault at Hanaoka, northern Honshu, Japan: Data acquisition and processing Hiroshi Sato +*, Yasutaka Ikeda ,, Toshifumi Imaizumi -, Hitoshi Mikada ., Shigeru Toda /, Hiroyuki Tsutsumi 0, Shin Koshiya 1, Ken Noda 1, Tanio Ito 2, Takahiro Miyauchi 2, Hiroshi Yagi 3, Masami Togo +*, Takaya Iwasaki ++, Mamoru Saka +, Naohsi Hirata +, Nobunao Matsu- ta ++, Tomonori Kawamura +,, Kouson Ishimaru +-, Takeshi Ikawa +.and Senya 30 Seismic profiling group +Earthquake Research Institute, The University of Tokyo, ,Graduate School of Science, The Uni- versity of Tokyo, -Faculty of Education and Human Sciences, Yamanashi University (Now at Grad- uate School of Science, Tohoku University), .Earthquake Research Institute, The University of Tokyo (Now at Graduate School of Engineering, Kyoto University), /Aichi University of Education, 0Graduate School of Science, Kyoto University, 1Department of civil & Environmental Engineer- ing, Iwate University, 2Department of Earth Sciences, Chiba University, 3Faculty of Education, Yamagata University, +*Hosei University, ++Graduate School of Science, The University of Tokyo (Now at National Taiwan University), +,Graduate School of Science and Technology, Chiba Univer- sity (Now at JGI Inc.), +-Power Reactor and Nuclear Fuel Development Corporation (Now at Japan Atomic Energy Agency), +.JGI, Inc. Abstract The Senya fault, northern Honshu, Japan, which generated the Rikuu earthquake (Mj 1.,) +230, is a typical intra-arc active thrust. Subsurface geometry provides essential information for better understanding strong ground motions and crustal deformation processes. A high-resolution seismic reflection survey was conducted along the 0-km long seismic line across the toe of the thrust to reveal the subsurface geometry. The seismic source was a Mini-vibrator truck and the receiver interval was +* m. The seismic data were processed by the standard common mid-point method. The Senya fault is clearly identified as a boundary between horizontal reflectors of the basin fill in the Yokote basin and moderately dipping reflectors beneath the Senya hills. The thrust occurred in late Miocene mudstone, and shows a flat and ramp geometry. The emergent thrust dips -* degrees down to /** m, and changes its dip to subhorizontal following the distribution of the mudstone. * email : [email protected] 腂腄++-**-, 膤腟膣膳腟腤膽膎 +++Bull. Earthq. Res. Inst. Univ. Tokyo Vol. 2+ ,**0pp. 31+*0 97

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Page 1: High-resolution seismic reflection profiling across the … Masami Togo+*, Takaya Iwasaki++, Mamoru Saka+, Naohsi Hirata+, Nobunao Matsu-ta++, Tomonori Kawamura+,, Kouson Ishimaru+-,

���� ���� ��� ��������: ����������� �����+�*���,���� �-������.���� �/��� ��0���� �1���� �1������2���� !2��"#�$3��%&'(+*��)*+,+��- .+��/�0+��12�3++��4567+,��89:;+-��<= >+.��?@30ABCDEFGHIJK+�%LMNDEOPQ�,�%LMNMNRSNTOPU�-�VWMNXYZ[UN\ ]^_ : %`MNMNRSNTOPU��.�%LMNDEOPQ ]^_ : LaMNMNRbNOPU��/�c6XYMN�0�LaMNMNRSNTOPU�1�)dMNbN\�2�?eMNSN\�3�VfMNXYN\�+*�CgMN�++�%LMNMNRSNTOPU ]^_ : hijkMN��+,�?eMNlmUNnoOPU ]^_ : ]p�DqUNnoOPQ��+-�rst�uvwxyz{| ]^_ : ]}�~���sOPxy����+.� ]p�DqUNnoOPQ

High-resolution seismic reflection profiling across the

Senya fault at Hanaoka, northern Honshu, Japan: Data

acquisition and processing

Hiroshi Sato+�*, Yasutaka Ikeda,�, Toshifumi Imaizumi-�, Hitoshi Mikada.�, Shigeru Toda/�,

Hiroyuki Tsutsumi0�, Shin Koshiya1�, Ken Noda1�, Tanio Ito2�, Takahiro Miyauchi2�, Hiroshi

Yagi3�, Masami Togo+*�, Takaya Iwasaki++�, Mamoru Saka+�, Naohsi Hirata+�, Nobunao Matsu-

ta++�, Tomonori Kawamura+,�, Kouson Ishimaru+-�, Takeshi Ikawa+.� and Senya 30 Seismic

profiling group

+�Earthquake Research Institute, The University of Tokyo, ,�Graduate School of Science, The Uni-

versity of Tokyo, -�Faculty of Education and Human Sciences, Yamanashi University (Now at Grad-

uate School of Science, Tohoku University), .�Earthquake Research Institute, The University of

Tokyo (Now at Graduate School of Engineering, Kyoto University), /�Aichi University of Education,0�Graduate School of Science, Kyoto University, 1�Department of civil & Environmental Engineer-

ing, Iwate University, 2�Department of Earth Sciences, Chiba University, 3�Faculty of Education,

Yamagata University, +*�Hosei University, ++�Graduate School of Science, The University of Tokyo

(Now at National Taiwan University), +,�Graduate School of Science and Technology, Chiba Univer-

sity (Now at JGI Inc.), +-�Power Reactor and Nuclear Fuel Development Corporation (Now at Japan

Atomic Energy Agency), +.�JGI, Inc.

Abstract

The Senya fault, northern Honshu, Japan, which generated the Rikuu earthquake (Mj 1.,) +230,

is a typical intra-arc active thrust. Subsurface geometry provides essential information for better

understanding strong ground motions and crustal deformation processes. A high-resolution seismic

reflection survey was conducted along the 0-km long seismic line across the toe of the thrust to

reveal the subsurface geometry. The seismic source was a Mini-vibrator truck and the receiver

interval was +* m. The seismic data were processed by the standard common mid-point method.

The Senya fault is clearly identified as a boundary between horizontal reflectors of the basin fill in

the Yokote basin and moderately dipping reflectors beneath the Senya hills. The thrust occurred in

late Miocene mudstone, and shows a flat and ramp geometry. The emergent thrust dips -* degrees

down to /** m, and changes its dip to subhorizontal following the distribution of the mudstone.

* email : [email protected] ]�++-�**-, %La�L��� +�+�+�

D E O P Q � �Bull. Earthq. Res. Inst.

Univ. TokyoVol. 2+ ],**0� pp. 31�+*0

� 97 �

Page 2: High-resolution seismic reflection profiling across the … Masami Togo+*, Takaya Iwasaki++, Mamoru Saka+, Naohsi Hirata+, Nobunao Matsu-ta++, Tomonori Kawamura+,, Kouson Ishimaru+-,

Key words : active fault, seismic reflection profiling, Senya fault, Rikuu earthquake, Northern Japan

+� ������������������� ���������� +230���� �Mj 1.,� ����������������� !"# ��$� +230�% �����&��'��������'("�� �)*�+,�Nakata, +310 ; Ikeda, +32- ; -�./� +32*�� 0123�4 �����+,5678� +320� 9: ;�+,�<=>�?�%��@���ABC��D/�E��(�� ��F��G�H������IE�J�� K#L�����M�N���OE���P��D/�E�J�QR����%�G"#�S/D� +330� 2T�UV��� ���W��U�E��X�Y�"� ������ABC�I����("�� �Z ��!4�<�# �Sato

et al., +331�% ��!4� +331�/D 32�K���"#[\�]^("�_`a>#�$%&b'c� ��(d�)�� +333� �]����% !4ef�g��h?��� E��i*�)� �+332�� +�./, �,**,� 9:�-j"#% &-j��� �Z ��!4�k7l�m.(Inof�h?�pq�%

,� ����$%&r��stuvw� ��/x/D�y)0z)�{<" �Sato, +33.�� �J�����1( W�(?G2h�3|4�)ea># �Fig. +�% �5�}6E����1�� 75�&����D>#3

|4�9"�?� �Sato et al., ,**,�% �������1 �~8��� �� /DUV��� ������� )<E� ,�����9:E� �Fig. ,�% �5� E9=�UV��(��W����}6E����������� ~8��(��W����}6E���d��� ���./� +310� ���%����@���;����"��� �<!�[\=����4� +302�/D +31-��/��_`a>� ��9 ,>9� +�����ea># ��<�?!�@{[\=� +31/9:�% ���� ������� />9� +

���� Aa>�?� ���./� +310�% �������9���4� ;��7�25�4�_`a>��#�������� ����B��������a>�?9?9:� ��BC�C����D�E����#%&-j��� t#�_`"#���4���� (����W��9�h?���./ �+310� �����]��"# �Fig. ,�% �&�9���9�h?��� ��./ �+310� /DF�9��9?%&������A}��� G���~8d�� Hd��IJ�������9a>� ���./� +310�% G���� ¡("��¢�£('��¤�¥¦£/DBea>����� ]�Ko§¨£�LMNO�©?ª«�¬­�eP®?���% ~8d��%&¯°F±�P®"#���� QM¯²�R£(� ³´µ7¶69¯S¤�T ?/D9�%  Hd��� ��P®���·d��¸UE�¹�R£/D9�% ��J}�ºb�R9

Fig. +. Generalized geological structure of northern Honshu (modified after Yamazaki et al., +32-).

i*VW» X

¼ 98 ¼

Page 3: High-resolution seismic reflection profiling across the … Masami Togo+*, Takaya Iwasaki++, Mamoru Saka+, Naohsi Hirata+, Nobunao Matsu-ta++, Tomonori Kawamura+,, Kouson Ishimaru+-,

������ �������� �� ������������������� ����� ����������� �!��� "#�$%��&���'���(��)��*��+�����������,-�./���0���1�2�� ���(�345���� �6�������2�� 78���9� !":�;<�=#>� �*���#�����&+�?�@A$%���&'"#�� B(C� D+310E �� FGHIJD.,AC+., Fig. ,E �K-������#����?��� )* /** m+7L��*���#��(�345�� M&$%��N��,O��-���* �� +230�-P ! DMj 1.,� Q.� +32, ; QRS� ,**-E �T�UV/�'� -P !�01W �2?�!X�YZ� �* ��01W �34�[��\ ��, �� 5 �&0]�'� N�6^� �_�-`#a7bc ��� d#e#3K=f8g$�� 01W �9h"i'� �* ��,jk:;2<�� -./ m�K=f� =>?��� -m@*� !l�<�&,O"#�-� DWm� +230 ; n(C�� +32*E�

-� ��������* ��<�A&ka:o-�B'"#� �5

pGq&8?�Cr�D�0��-�st�uE ��

FGH Dj�jE �-'�I� 0 km�vw�JK�L'�' DFig. -E� L'� N�JK�01W ��*+��x���y ��2%���zG{�|M�9N}~��=��9� !":�'���O"#' DTable +E� !X�3�:� !���������pG{G DIVI T+/*** ; RP� +330E ��Q�'� �J��� !����R�z�{4�p�5HG3q�� JGI, G�daps .�Q-� �I�4pG5�, msec, +2*���4��S�'��T����R�U�,2 Hz�a�� 3�V��Q�'� �TNw�� +* m,

�TNw�� ,* m��'� �!�q�G��U���+*�+,* Hz�K�� �q�G��2�� q�G���,*W� q{ ¡��X¢� +*£��'&� IY�3g$&Z¤�� �¥[�¦\�� =�]A�UK�M§���9U�^_��'��84 0*���4�34 +,*

���4�`a¨�b©��'� �!N& 0*���4 N���'lN�� 0*���4�+?�ª�0�� Uf�'b©�3« 5���-j¬¬<cd b©?��� '� N�'�}~��</&:o-&� JK��­®> -0¯��}~�&O�#�-� DFig. /E�°J� +330e 1± ,1f�� 2± 2fL�²³"#�g´ �9µS�O'� JK�st�h DRP +.*E �FGH DRP ./*E �­®>¶i�C�·M A� %MAa¸A�¹�º�¸ -U�µS��S&»j�2 '�

Fig. ,. Geological map around the Senya hills showing the location of the Senya 30 seismic line. The geological map

is after Usuta et al. (+310) modified by authors based on new geological survey.

�* ����9� !":

¼ 99 ¼

Page 4: High-resolution seismic reflection profiling across the … Masami Togo+*, Takaya Iwasaki++, Mamoru Saka+, Naohsi Hirata+, Nobunao Matsu-ta++, Tomonori Kawamura+,, Kouson Ishimaru+-,

�������������� �������� �������� Fig. .�� ������������ Table ,� !�� "������#$!%Mer-

cury International Technology Co. Ltd.������&'()*+ iXL ,Ver. ..,- .�����/(�� ,0-�1234�567������&'()*+ Super

X.���� 89�����:�;�%#<"�����=�.>�?@�'A�BC"�����A��DE.���minimun

phase correlationF�GH��IJK:� SEGY'L�M/(NO�P:�� QR�STUVWIX<�Y��� CMP��U.Z[� \]^�_`.@abQR�;�% CMP sort.J�� ,Fig. --� c�� dO�_��e<fDgh.ijkl'AB�� ,pre-

filter-.m�!�Pn�� first break suppression, gain

recovery, whitening deconvolution��.J��� o�� p�q�Vrst��@�uv��v���jwx�yz{|.Y$�� yz� }z ,-** m/s- .~�z�� ,+,2**�,,1** m/s- N����@�q�.wxm�!������<���.J��F� /** m��N����.J�����'�uB ,Fig. /- .�h!� NMO�q.J��� o�������'�uB.��}!�Y�.Mu�������������������F��� +/�+** Hz���C��'AB��.m�!� ��Mu������.��!�� Pn�� ��D����. Z?@�x�� fox�¡N���¢v£u¤.��@ FX prediction filter.m�!�� ¥�O�������.J�%�h!���O�¦��y �§��%�� ¨©�ª�I�«¬­��<@��<datum correction.��!��®n:���FMu������¦�. Fig. 0�� ����¦�. Fig. 1� !��

.� ���������¯°��,CMP+�-.*-N����������±n�²����%³´�µ¶/(�·n:@� �9� /**

Fig. -. Detailed location of the Senya 30 seismic line. The base map is at a scale of + : ,/,*** issued from

the Geographical Survey Institute.

Table +. Data acquisition parameters for the Senya 30

seismic line.

¸¹S�º »

¼ 100¼

Page 5: High-resolution seismic reflection profiling across the … Masami Togo+*, Takaya Iwasaki++, Mamoru Saka+, Naohsi Hirata+, Nobunao Matsu-ta++, Tomonori Kawamura+,, Kouson Ishimaru+-,

m�������������� ������������������ +./�,./ km/s���� ��!" /** m#$�%������&'������ ()*�+,-./����(01�� ,./&' . km/

s���� ��!" 23��456789�:�;<.,AC-+. ; Fig. ,= �>?@�AB$ /** m.CD� ��E��F'7G�HI>?@�AB.+J!GKLM67G<NOP&� +310="�8(QR��HI�SRR�T�����>?@KU�VW�8XY�

8Z[\�%T�����9�:�;]���^&'�_�_`abcd@#%�U@KLM67G <Fig. 2=">?E@efU������K>?g%�hij�����klK�Rm7R�G" E@hij��K�R$ 1** m��no67G" CMP/-*�2/*������E@�pq����CG(� $ 2**�3** m�Pr���.pq67GK E�8" >?g�st�>?E@���.uvwx&'�G��@(�y�RzD� ��E�.z{GE@�ij������K�|!G}K&'� U%.z�R~E@wxK��R�GK��67G" ��E���>?E@��E@�����U@(�E@�ijK�|�����!U�ym��E@ <emergent thrust= ���������K�R��������������! <Fig. 2=">?g�U�U�K P�� &' E�R� >?g%����������@K>?@%�&'��67GK��'7G" >?g� CMP.**&' 0**�������q������(01!G���� <Sy ;

Fig. 2= (sij�����.�&QR@�����('�HI��QR�G" }��HI� U�U�&'>?@AB��HIK E67G">?g%�CMP/-*�10*����$ � ,**�.** m.��-����&'� ~�2����E@(����G <F, ; Fig. 2=" !���� �T�sij����(01�� %T�Pr�����K�G" }���E@ <F,= >?@%�XY .¡¢�8~���}�£¢.�QRCMP/,*�0**�>?@��q@ <growth strata ; Fig. 2= (��678~�K��67G" >?g� CMP/**�02*

���$ ,** m��>?@���@��HI��QR�������!¤¥��XY@(��!G <Sy, ;

Fig. 2=" }�XY@ CMP/**�//*����s�.�&QR@����RzD� >?g���������£¢.�QR��678¤¥�� piggy-back basin�XY@KLM67G <¦§��O� +332="¨©ªU%� -�. km/s���� ���� �� ��«����.���" ¬K�R_`­�®ªx�®ª¯°x&'��67GU�.,±�R�G" ªU�gkl� CMP02*�� >?gh�.��!G>?@��HI���XY@.�T���Gh��²��E@ <F- ; Fig. 2= (����G" }�E@d³E@.+J�� ����s.ij����(01!G" ����������&'$ /** m ´��hij�E@(no��G <Fig. 2=" }�E@�U%pq.µ�R>? 30¶·����CG(� ¨©ªU��²£¢��!!GKPr"#�ij�$�.��!G~�K��

Fig. .. Generalized processing flow chart for the Senya

30 seismic line.

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Page 6: High-resolution seismic reflection profiling across the … Masami Togo+*, Takaya Iwasaki++, Mamoru Saka+, Naohsi Hirata+, Nobunao Matsu-ta++, Tomonori Kawamura+,, Kouson Ishimaru+-,

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km�� -*�������������� �Sato et al.,

,**,��

/� ���+230��� � �M 1.,� !"#$%&'()*�

�+,���-�.�/��0��1234�56��17��8 ���� 19��:;� !<=%�>�?@8 56�����ABCDEBFG'�HI!J4�KLMN�� �emergent thrust� �-O8PQ��RSCTUFD�N�VWX�YZV1"[$���\E��]^1)=%� �%8 _�`ab�cd��� ./ef.*e.��!J$856�����ghEij + km�_ab��Ek�4�Elm����

� ��no!pq�1-%O8 rst5uv wx �vh�yvz{|}~ sd��z{h1�8 � ���� �����)����)���!�%��%� ��^]���)�UFD!�%��%� ���1�8 �1���������E���������^]��� !¡�$%� �no�8 .¢�£�no¤¥ynoG¦§B¨���!©ª�$%�

56 30���� §«¬G­®� : ¯°��± �.¢�£�no¤�²³´�­®� : ¯°��± �.¢�£�no¤�§«¬G:µ}� : ¯°��±��¶s·�Z¸¹º�

Fig. /. Optimum stacking velocities determined by velocity analysis and distribution of number of folds along

a CMP stacking line.

Table ,. Processing parameters for CMP Senya 30

seismic line.

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Page 7: High-resolution seismic reflection profiling across the … Masami Togo+*, Takaya Iwasaki++, Mamoru Saka+, Naohsi Hirata+, Nobunao Matsu-ta++, Tomonori Kawamura+,, Kouson Ishimaru+-,

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Page 10: High-resolution seismic reflection profiling across the … Masami Togo+*, Takaya Iwasaki++, Mamoru Saka+, Naohsi Hirata+, Nobunao Matsu-ta++, Tomonori Kawamura+,, Kouson Ishimaru+-,

�� ���������� � ������� �� �������� ������������ ������ � ������������ � � �!"����� � #� ����������� ��#$ ��%������ &' ���� ( �)*�+��� �,-� ��.��� /�'0�1�2����3� �4����� 56"��78-��Chrisitne Orgren �4��9:�;<����� �=> �?"���� @A 2 ����!��� BCDE �"#$�F%&G'HIJ��KL ( ��M��N�;<�� � O PQ��)RS

� �*'L T��� �� +333� ;+ : �,-.UVWXYUZ/[0%\�]^"Z� _` �N� ab ,1� /�++.

Ikeda, Y., +32-, Thrust-front migration and its mechanism :

Evolution of intraplate thrust fault systems, Bull. Dept.Geogr., Univ. Tokyo, +/, +,/�+/3.

����������,-���L�c�1�2��d�12e3� ,**,S fghijklUVmS ,/. p., ���n4o� ��S

pPq5rqstHIJ� +31/� T6 .278u9:v;wx6y<5�zS pPq5rqstHIJS

��R=�>� ?��{|<������ +32*� +2307?}�~�jk� ��� @;� //� 13/�2//.

Nakata, T., +310, Quaternary tectonic movements in Central

Tohoku district, Northeast Japan, Sci. Rep. Tohoku Univ.,1th Ser. (Geography), ,0, ,+-�,-0.

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Sato, H., Ikeda, Y., Imaizumi, T., Mikada, H., Tsutsumi, H.,

Koshiya, S., Togo, M., Toda, S., Kawamura, T., Matsuta,

N., Yanagi, H., Itoh, T., Miyauchi, T., Orgren, C., Shishi-

kura, M., Suzuki, H., Soeda, Y., Noda, K., Yagi, H., Kuma-

moto, T., Hirata, N., Iwasaki, T., Saka, M., Ichinose, Y.,

Aoki, Y., Shimizu, N., Ishimaru, K., Sakai, R. and Ikawa,

T., +331, Evolution of the active Senya thrust fault,

northern Honshu, Japan, Abstract of Annual Meeting,Seismological Soc. Japan, No. ,, ++1.

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Sato, H., +33., The relationship between late Cenozoic tec-

tonic events and stress field and basin development in

northeast Japan, J. Geophys. Res., 33, ,,,0+�,,,1..

Sato, H., Hirata, N., Iwasaki, T., Matsubara, M. and Ikawa, T.,

,**,. Deep Seismic Reflection Profiling across the Ou

Backbone Range, Northern Honshu Island, Japan. Tec-tonophysics, -//, .+�/,.

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�Received January +/, ,**1��Accepted February 3, ,**1�

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