国立大学法人 （PDF:711KB）

࿾㔡੍⍮䈱䈢䉄䈱ᣂ䈢䈭
᷹ⷰ⎇ⓥ⸘↹䋨╙䋲ᰴ䋩䈮䈍䈔䉎
ᐔᚑ䋱䋹ᐕᐲታᣉ⁁ᴫ
࿖┙ᄢቇᴺੱ
᷹ⷰ⎇ⓥ⸘↹ផㅴᆔຬળ
䋲䋰䋰䋷ᐕ䋱䋲᦬䋱䋷ᣣ
ᧄ⾗ᢱ䈲2007ᐕAGU Fall Meeting䈮䈍䈇䈩
⊒⴫䈘䉏䈢એਅ䈱⺰ᢥ䉕ర䈮૞ᚑ䈚䈢
Effects of heterogeneous structures of
the seismic velocity and the stress field on
earthquake generations elucidated by
dense temporary seismic networks
Aitaro Kato*
Shinichi Sakai*
Eiji Kurashimo*
Toshihiro Igarashi*
Takashi Iidaka*
Naoshi Hirata*
Takaya Iwasaki*
Toshihiko Kanazawa*
Group for the aftershock observations of the 2007 Noto Hanto Earthquake
Group for the aftershock observations of the 2007 Niigataken Chuetsu-oki Earthquake
* Earthquake Research Institute, Univ. of Tokyo (ERI)
ᦨㄭ⊒↢䈚䈢ਥ䈭࿾㔡
2004 ᣂẟ⋵ਛ⿧࿾㔡
2007 ⢻⊓ඨፉ࿾㔡
2007 ᣂẟ⋵ਛ⿧ᴒ࿾㔡
౒ㅢὐ
• Mw ~ 6.6
• 㜞ⷺ䈱ㅒᢿጀ
• ᣂẟ㵥␹ᚭᱡ䉂㓸ਛᏪ
• ᵴⶠᦛᏪ
⒮ኒ૛㔡᷹ⷰ
⋡⊛䋺 㔡Ḯၞ䈱ਇဋ⾰᭴ㅧ䉕᣿䉌䈎䈮䈜䉎
1) 2004 ᣂẟ⋵ਛ⿧࿾㔡
᷹ⷰᦼ㑆
᷹ⷰὐᢙ
ౣ᳿ቯ䈘䉏䈢૛㔡ᢙ
: 2004/10/24 – 11/26
: 56 ὐ
: 2668 ୘
2) 2007 ᣂẟ⋵ਛ⿧ᴒ࿾㔡
᷹ⷰᦼ㑆
᷹ⷰὐᢙ
ౣ᳿ቯ䈘䉏䈢૛㔡ᢙ
: 2007/07/16 – 08/30
: 48 ὐ
: 881 ୘
3) 2007 ⢻⊓ඨፉ࿾㔡
᷹ⷰᦼ㑆
᷹ⷰὐᢙ
ౣ᳿ቯ䈘䉏䈢૛㔡ᢙ
: 2007/03/25 – 05/22
: 80 ὐ
: 1600 ୘
⸃ᨆᚻᴺ
a) ࿾Ზ᭴ㅧ
䊃䊝䉫䊤䊐䉞䊷ᴺ : tomoDD-code [ Zhang and Thurber, 2003 ]
䊂䊷䉺 : ೔⌕ᤨ෸䈶
Double difference arrival times
b) ᔕജ႐
ᔕജ䊁䊮䉸䊦䉟䊮䊋䊷䉳䊢䊮ᴺ : MOTSI-code [ Abers and Gephart, 2001 ]
䊂䊷䉺 : ೋേ䈱᛼䈚ᒁ䈐
䋲䋰䋰䋴ᐕᣂẟ⋵ਛ⿧࿾㔡䈱⒮ኒ૛㔡᷹ⷰ䋨ෳ⠨⾗ᢱ䋩
Kato et al (2006)
M6.0એ਄䈱࿾㔡5୘
䋨A1-A5)䉕฽䉃㕖Ᏹ䈮
ᵴ⊒䈭૛㔡ᵴേ䈏
᷹ⷰ䈘䉏䈢
䋲䋰䋰䋴ᐕᣂẟ⋵ਛ⿧࿾㔡䋨ෳ⠨⾗ᢱ䋩
[ 䊃䊝䉫䊤䊐䉞䊷 ]
•ᩰሶὐ㑆㓒
Xゲ (E35S+) : 3km int.
Yゲ (N35E+) : 3km int.
Zゲ (D +)
: 3km int.
•૶↪䈚䈢࿾㔡ᢙ : 915
•ᵄ✢䈱ᧄᢙ
P: 46,517 S: 44,527
•Double Differences (䉦䉺䊨䉫)
P: 260,202, S: 242,373
•Double Difference
( ᵄᒻ⋧㑐 > 0.85 )
P: 38,540, S: 30,501
Kato et al (2006)
Pᵄㅦᐲ᭴ㅧ䈱ᢿ㕙࿑
Kato et al (2006, JGR)
•਄⋚஥䈏ૐㅦᐲ
: ᣣᧄᶏ᜛ᄢᤨ䈮ᒻᚑ䈘䉏䈢half graben 䈮ၸⓍ䈚䈢
ਅ⋚஥䈲㜞ㅦᐲ䈱ၮ⋚ጤ
•૛㔡䈲ㅦᐲႺ⇇䈮ᴪ䈦䈩⊒↢䈚䈩䈇䉎
- ਄⋚䈫ਅ⋚䈱㑆
- ၮ⋚ጤౝㇱ
•ᧄ㔡ઃㄭ䈱ૐㅦᐲ㗔ၞ 㹢 ᵹ૕䈱ሽ࿷
ฦᷓ䈘䈪䈱Pᵄㅦᐲ
Kato et al (2006, JGR)
਄⋚஥ၸⓍጀ䈏᧲⷏ᣇะ䈮િᒛ
ၸⓍጀ䈏ෘ䈒䈭䈦䈩䈇䉎
ᔕജ႐䈱ਇဋ⾰ᕈ
ਛᄩㇱ (ᧄ㔡㗔ၞ)
V1 : W20N ~ W30N
(ᐢၞᔕജ႐䈫⺞๺⊛)
V3 : 䈾䈿ု⋥
ධ⷏ㇱ
V1 : W ~ W10N
V3 : ု⋥ (⺋Ꮕᄢ)
ർ᧲ㇱ
V1 : W15N
V3 : ု⋥䋨⺋Ꮕᄢ䋩
•ධ⷏ㇱ䈱ᦨᄢਥᔕജ V1 䈱࿁ォ
䈲95䋦᦭ᗧ
ᔕജゲ䈱ᣇะ䈏ᄌൻ䈜䉎႐ᚲ䈮
ᧄ㔡䈏૏⟎䈚䈩䈇䉎
Kato et al (2006, JGR)
ᔕജゲ䈱࿁ォ䈫ਇဋ⾰᭴ㅧ䈫䈱㑐ଥ
2004ᐕᣂẟ⋵ਛ⿧࿾㔡
ᧄ㔡䈲ၸⓍጀ䈱ෘ䈘䈫ᦨᄢਥᔕജゲ䈱ᣇะ䈏ᕆỗ䈮ᄌൻ䈜䉎႐ᚲ䈮૏⟎䈜䉎
࿾㔡ᵄㅦᐲ᭴ㅧ䈫ᔕജ႐䈱ਇဋ⾰෸䈶਄ㇱ࿾Ზ䈱☼ᒢᕈ⊛ᄌᒻ䈏
㔡Ḯၞ䈻䈱ᔕജ㓸ਛ䊜䉦䊆䉵䊛䉕⸃᣿䈜䉎㊀ⷐ䈭㎛䈪䈅䉎
䋲䋰䋰䋷ᐕᣂẟ⋵ਛ⿧ᴒ࿾㔡䈱⒮ኒ૛㔡᷹ⷰ
ᧄ㔡䈲૛㔡ၞ䈱ർ᧲┵
䋲䋰䋰䋷ᐕᣂẟ⋵ਛ⿧ᴒ࿾㔡
[ 䊃䊝䉫䊤䊐䉞䊷 ]
ᩰሶὐ㈩⟎
Xgrid (E35S+) : 5km int.
Ygrid (N35E+) : 5km int.
Zgrid (D +)
: 3km int.
•⸃ᨆ䈮૶↪䈚䈢࿾㔡ᢙ: 881
•ᵄ✢䈱ᧄᢙ
P: 39,594
S: 36,548
•ੑ㊀⿛ᤨᏅ (䉦䉺䊨䉫)
P: 235,778
S: 209,020
•ੑ㊀⿛ᤨᏅ
( ᵄᒻ⋧㑐 > 0.85 )
P: 40,062
S: 57,975
Pᵄㅦᐲ᭴ㅧ
ർ᧲ㇱ (Y=+5, +10km)
• ᧲௑ᢳ䈫⷏௑ᢳ䈱౒ᓎ䈭㕙਄䈮૛㔡ಽᏓ
• ૛㔡ၞ䉋䉍ᷓㇱ䈱㜞ㅦᐲጀ䈲਄䈮ಲ
ਛᄩㇱ䈎䉌ධ⷏ㇱ
• ᄙ䈒䈱૛㔡䈲᧲௑ᢳ
• ૛㔡ၞ䉋䉍ᷓㇱ䈱㜞ㅦᐲጀ䈲ਅ䈮ಲ
㜞ㅦᐲ䈫ૐㅦᐲ䈱Ⴚ⇇䈮૛㔡䈏ಽᏓ
Vp>6.0km/s䈮૛㔡䈏ಽᏓ
2004ᐕᣂẟ⋵ਛ⿧࿾㔡䈫⇣䈭䉎
ㅦᐲႺ⇇ၞ
᳓ᐔᣇะ䈱ㅦᐲ᭴ㅧᄌൻ䈫૛㔡ಽᏓ
઒
⺑
⎕უ㐿ᆎὐ䈲ർ᧲ㇱ䈱⷏௑ᢳ䈜䉎ᢿጀ㕙䈱ᦨᷓㇱ
⎕უ䈲ධ⷏䈮ㅴⴕ䈚䈩᧲௑ᢳ䈱ᢿጀ㕙䈮ਸ਼䉍⒖䈦䈢
䋲䋰䋰䋷ᐕ⢻⊓ඨፉ࿾㔡
㔡Ḯၞ䈲࿾⾰ቇ⊛䈮䈲⍴❗ᄌᒻ
⍴❗䊧䊷䊃䈲ਛ⿧࿾ၞ䉋䉍ዊ
ᣂẟ㵥␹ᚭᱡ䉂㓸ਛᏪ䈮䈲
฽䉁䉏䈩䈇䈭䈇
•࿶❗ゲ䈏ᤨ㑆⊛䈮ᄌൻ䈚䈢
ᓟᦼਛᣂ਎ ( ~ 10Ma) :
N-Sᣇะ⍴❗
ᓟᦼ㞲ᣂ਎ ( ~ 3Ma) :
WNW-ESEᣇะ⍴❗
Okamura (2007)
䋲䋰䋰䋷ᐕ⢻⊓ඨፉ࿾㔡䈱⒮ኒ૛㔡᷹ⷰ
[ 䊃䊝䉫䊤䊐䉞䊷 ]
•ᩰሶὐ㈩⟎
Xgrid (E55S+) : 3km int.
Ygrid (N55E+) : 3km int.
Zgrid (D +)
: 3km int.
⸃ᨆ䈮૶↪䈚䈢࿾㔡ᢙ : 971
•ᵄ✢䈱ᧄᢙ
P: 44,278
S: 36,758
•ੑ㊀⿛ᤨᏅ (䉦䉺䊨䉫)
P: 232,063
S: 172,401
•ੑ㊀⿛ᤨᏅ
(ᵄᒻ⋧㑐 > 85% )
P: 22,897
S: 25,122
Kato et al (2007, EPS)
Pᵄㅦᐲ᭴ㅧ䈫ౣ᳿ቯᓟ䈱૛㔡ಽᏓ
•਄⋚஥
: High-Vp
•ਅ⋚஥
: Low-Vp
•૛㔡䈲ㅦᐲႺ⇇䈮ಽᏓ
䊶ᧄ㔡䈱㔡Ḯઃㄭ䈮ૐㅦᐲ
Kato et al (2007, EPS)
࿾Ზౝᵹ૕䈏ᧄ㔡䈱
㔡Ḯઃㄭ䈮ሽ࿷䈜䉎⸽᜚
ૐᲧᛶ᛫૕䈏㔡Ḯઃㄭ䈮䈅䉍
䋨 MT តᩏ䋩
࿾㔡ᵄㅦᐲ䈱ૐㅦᐲ૕
Resistivity model
Yoshimura et al
(2007)
ᔕജ႐䈱ਇဋ⾰
ᵻㇱ (ᷓ䈘0 - 4 km)
• ᦨᄢਥᔕജゲ V1 : WNW – ENE
ᐢၞᔕജ႐䈫⺞๺⊛
• ᮮ䈝䉏ᢿጀဳ
ᷓㇱ (ᷓ䈘9 - 10 km)
•ᦨᄢਥᔕജゲ V1 : NW – NE
•ㅒᢿጀဳ
ᷓ䈘ᣇะ䈱ᔕജ႐䈱ᄌൻ䈏ᧄ㔡䈱Ṗ䉍ᣇะ䉕ⷙቯ
Ozawa et al (2007)
ᧄ㔡䈱Ṗ䉍ᣇะ
•ᷓㇱ䈲❑䈝䉏
䊶ᵻㇱ䈲ᮮ䈝䉏
Ṗ䉍ᣇะ䈱ᄌൻ䈲ᔕജ႐䈱ᄌൻ䈫⺞๺⊛
ᧄ㔡䈱⎕უ䈲䋲䈧䈱⇣䈭䉎ᔕജ႐䉕ㅢㆊ䈚䈢
Fault-valve model
(Sibson, 2002; Sibson, 2007)
㔡Ḯ䈱ਅ䈮ᵹ૕
㜞ⷺ䈱❑䈝䉏ᢿጀ䈏⎕უ
ᵻㇱ䈪䈲ᔕജ႐䈱ᣇะ䈮⎕უ䈏ㅴዷ
૛㔡ᢙ䈫࿾Ზౝਇဋ⾰᭴ㅧ䈫䈱㑐ଥ
Vp䈱ᄌൻ䈏ᄢ䈐䈇႐ᚲ䈪䈲૛㔡ᢙ䈏ᄙ䈇
ᱜ䈱⋧㑐䈅䉍
઒⺑䋺 ࿾Ზ᭴ㅧ䈏ਇဋ⾰䈭䈾䈬૛㔡䈏ᄙ䈇
䉁
䈫
䉄
ᦨㄭᣣᧄᶏᴪ䈇䈮⊒↢䈚䈢ౝ㒽࿾㔡䈫࿾Ზౝਇဋ⾰
࿾Ზᄌേ䈮䉋䈦䈩૞䉍಴䈘䉏䈢ⶄ㔀䈭᭴ㅧ䈏ᧄ㔡䉇૛㔡ᵴേ䉕ᒁ䈐⿠䈖䈜
•૛㔡䈲ㅦᐲႺ⇇䈮ᴪ䈦䈩⊒↢
ᣢሽ䈱ᢿጀ䈱ౣᵴേ
•࿾㔡ᵄㅦᐲ᭴ㅧ䉇ᔕജ႐䈏ⓨ㑆⊛䈮ᄢ䈐䈒ᄌൻ䈚䈩䈇䉎
䊶㔡Ḯઃㄭ䈮ૐㅦᐲ䊶ૐᲧᛶ᛫૕
•ᐢၞᔕജ႐䈮ว䉒䈭䈇㜞ⷺ䈭ᢿጀ
ᔕജ㓸ਛ䈱ේ࿃
࿾Ზౝᵹ૕
ᱜᢿጀ䈱ౣᵴേ
࿾Ზౝਇဋ⾰᭴ㅧ䈲ౝ㒽࿾㔡䈱⊒↢䈮ᄢ䈐䈒㑐䉒䈦䈩䈇䉎
䈘䉌䈮⹦⚦䈭᷹ⷰ⎇ⓥ䉕ⴕ䈉䈖䈫䈮䉋䉍ౝ㒽࿾㔡䈱⊒↢䊜䉦䊆䉵䊛䈱ℂ⸃䈏
ᷓ䉁䉎䈪䈅䉐䈉
⻢ㄉ
એਅ䈱ᣇ䇱෸䈶㑐ଥᯏ㑐䈮ᗵ⻢⥌䈚䉁䈜䇯
H. Zhang᳁䈱䊃䊝䉫䊤䊐䉞䊷⸃ᨆ䊒䊨䉫䊤䊛 TomoDD䉕૶↪䈚䈢䇯
G. Abers᳁䈱ᔕജ䊁䊮䉸䊦䉟䊮䊋䊷䉳䊢䊮⸃ᨆ䊒䊨䉫䊤䊛 MOTSI 䉕૶↪䈚䈢䇯
㒐ἴ⑼ቇᛛⴚ⎇ⓥᚲ䋬᳇⽎ᐡ䋬੩ㇺᄢቇ䋬᧲ർᄢቇ䋬਻Ꮊᄢቇ䈱ቯᏱ᷹ⷰὐ䈱ᵄᒻ
䊂䊷䉺䉕૶↪䈚䈢䇯
࿑䈱૞ᚑ䈮䈲GMT (Wessel and Smith, 1995)䉕૶↪䈚䈢䇯
2007ᐕᣂẟ⋵ਛ⿧ᴒ࿾㔡૛㔡᷹ⷰ䉫䊦䊷䊒
1)᧲੩ᄢቇ࿾㔡⎇ⓥᚲ
2)ർᶏ㆏ᄢቇᄢቇ㒮ℂቇ⎇ⓥ㒮㒝ዻ࿾㔡Ἣጊ⎇ⓥ᷹ⷰ䉶䊮䉺䊷
3)ᒄ೨ᄢቇℂᎿቇㇱ㒝ዻ࿾㔡Ἣጊ᷹ⷰᚲ
4) ᧲ർᄢቇᄢቇ㒮ℂቇ⎇ⓥ⑼㒝ዻ࿾㔡䊶Ἣጊ੍⍮⎇ⓥ᷹ⷰ䉶䊮䉺䊷
5) ฬฎደᄢቇᄢቇ㒮ⅣႺቇ⎇ⓥ⑼㒝ዻ࿾㔡Ἣጊ䊶㒐ἴ⎇ⓥ䉶䊮䉺䊷
6)੩ㇺᄢቇ㒐ἴ⎇ⓥᚲ
7)਻Ꮊᄢቇᄢቇ㒮ℂቇ⎇ⓥ㒮㒝ዻ࿾㔡Ἣጊ᷹ⷰ⎇ⓥ䉶䊮䉺䊷
8)㣮ఽፉᄢቇℂቇㇱ㒝ዻධ⷏ፉቅ࿾㔡Ἣጊ᷹ⷰᚲ
2007ᐕ⢻⊓ඨፉ࿾㔡૛㔡᷹ⷰ䉫䊦䊷䊒
1)᧲੩ᄢቇ࿾㔡⎇ⓥᚲ
2)ർᶏ㆏ᄢቇᄢቇ㒮ℂቇ⎇ⓥ㒮㒝ዻ࿾㔡Ἣጊ⎇ⓥ᷹ⷰ䉶䊮䉺䊷
3)ᒄ೨ᄢቇℂᎿቇㇱ㒝ዻ࿾㔡Ἣጊ᷹ⷰᚲ
4)᧲ർᄢቇᄢቇ㒮ℂቇ⎇ⓥ⑼㒝ዻ࿾㔡䊶Ἣጊ੍⍮⎇ⓥ᷹ⷰ䉶䊮䉺䊷
5)ජ⪲ᄢቇℂቇㇱ
6)㊄ᴛᄢቇᄢቇ㒮⥄ὼ⑼ቇ⎇ⓥ⑼
7)ฬฎደᄢቇᄢቇ㒮ⅣႺቇ⎇ⓥ⑼㒝ዻ࿾㔡Ἣጊ䊶㒐ἴ⎇ⓥ䉶䊮䉺䊷
8)੩ㇺᄢቇ㒐ἴ⎇ⓥᚲ
9)਻Ꮊᄢቇᄢቇ㒮ℂቇ⎇ⓥ㒮㒝ዻ࿾㔡Ἣጊ᷹ⷰ⎇ⓥ䉶䊮䉺䊷
10)㣮ఽፉᄢቇℂቇㇱ
11)↥ᬺᛛⴚ✚ว⎇ⓥᚲ
12)㒐ἴ⑼ቇᛛⴚ⎇ⓥᚲ