[講演要旨] 2011年東北地方太平洋沖地震後の南関東における地震活動と歴史地震の震源域への影響

全文

(1)ᱧผ࿾㔡㩷 ╙㪉㪏ภ䋨㪉㪇㪈㪊䋩㩷㪈㪍㪇㗁. ［講演要旨］. 2011 ᐕ᧲ർ࿾ᣇᄥᐔᵗᴒ࿾㔡ᓟ䈱ධ㑐᧲䈮䈍䈔䉎࿾㔡ᵴേ䈫ᱧผ࿾㔡䈱㔡Ḯၞ䈻䈱ᓇ㗀 ⍹ㄝጪ↵*䊶㈬੗ᘕ৻䊶ፉፒ㇌ᒾ䊶૒┻ஜᴦ䊶㢬ጟᒄ䋨᧲ᄢ࿾㔡⎇䋩. Seismicity in the southern Kanto region after the 2011 Tohoku-oki Earthquake and the effect on source regions of historical large earthquakes Takeo Ishibe, Shin’ichi Sakai, Kunihiko Shimazaki, Kenji Satake, and Hiroshi Tsuruoka (ERI, the Univ. of Tokyo) 1㧚ߪߓ߼ߦ 2011 ᐕ 3 ᦬ 11 ᣣ䈮ችၔ⋵ᴒ䉕㔡Ḯ䈫䈚䈩⊒↢䈚䈢 2011 ᐕ ᧲ർ࿾ᣇᄥᐔᵗᴒ࿾㔡䋨M9.0䋻᳇⽎ᐡ䋩䈲䋬⸘ེ᷹ⷰ䈏ᆎ䉁䈦䈩એ᧪ᦨᄢ䈱࿾㔡䈪䈅䉍䋬䈠䈱ᓟ䈮᧪ⷅ䈚䈢Ꮒᄢᵤᵄ䈮䉋䈦䈩↟ᄢ䈭ⵍኂ䈏⊒↢䈚䈢䋮ᧄ㔡ᓟ䈮䈲䋬㔡Ḯၞ䈪㕖Ᏹ䈮ᵴ⊒ 䈭૛㔡ᵴേ䈏᷹ⷰ䈘䉏䈩䈇䉎䈣䈔䈪䈭䈒䋬䈠䈱๟ㄝၞ䈮䈍䈇䈩䉅᣿⍎䈭࿾㔡ᵴേᄌൻ䈏ႎ๔䈘䉏䈩䈇䉎䋨଀䈋䈳䋬Hirose et al., 2011䋩䋮䉁䈢䋬3 ᦬ 12 ᣣ䈱㐳㊁⋵䊶ᣂẟ⋵Ⴚઃㄭ䈱࿾㔡䋨M6.7䋩䋬4 ᦬11 ᣣ䈱⑔ፉ⋵ᵿㅢ䉍䈱࿾㔡䋨M7.0䋩䈭䈬䈱⺃⊒࿾ 㔡䉅⊒↢䈚䈢䋮䈖䉏䉌䈱੐ታ䈲䋬᧲ർᴒ࿾㔡䈮䉋䉎ᔕജᄌൻ䈏 ᐢ▸䈮෸䈶䋬੹ᓟ䉅ᄢ࿾㔡䈏⺃⊒䈘䉏䉎น⢻ᕈ䉕␜ໂ䈜䉎䋮㚂ㇺᯏ⢻䈏㓸ਛ䈜䉎ධ㑐᧲䈲䋬ᄥᐔᵗ䊒䊧䊷䊃䈫䊐䉞䊥䊏䊮 ᶏ䊒䊧䊷䊃䈏㒽䈱䊒䊧䊷䊃䈱ਅ䈮ᴉ䉂䈖䉃ⶄ㔀䈭䊁䉪䊃䊆䉪䉴 ਅ䈮䈅䉍䋬᭽䇱䈭ⵍኂ࿾㔡䈏⊒↢䈚䈩䈐䈢䋮䈠䈖䈪ᧄ⎇ⓥ䈪䈲䋬 ᧲ർᴒ࿾㔡䈮䉋䉎㕒⊛䉪䊷䊨䊮ᔕജᄌൻ䋨㰱CFF䋩䉕⸘▚䈚䋬䈠䈱ᓇ㗀䈮䈧䈇䈩⺞ᩏ䈚䈢䋮ǍCFF ߇ᱜߩ႐วߦߪ࿾㔡ᵴേ߇ ᵴ⊒ൻߒ㧘⽶ߩ႐วߦߪ㕒Ⓩൻߔࠆߎߣ߇ߘࠇߙࠇᦼᓙߐ ࠇࠆ㧚. ৻ᣇ䈪䋬ⵍኂ࿾㔡䈮ኻ䈚䈩㰱CFF 䈏 0.1 bar એ਄Ⴧട䈚䈢࿾ 㔡䈲 7୘䋬0.1 barએ਄ᷫዋ䈚䈢࿾㔡䈲6୘䈪䈅䈦䈢䋮䈖䈱䈉䈤䋬 ർદ⼺䋬દ⼺ඨፉᴒ䋬દ⼺ᄢፉㄭᶏ࿾㔡䈲䋬䈇䈝䉏䉅ᓸዊ࿾ 㔡䈮ኻ䈚䈩㰱CFF 䈏Ⴧട䈚䈢દ⼺䉕฽䉃㕒ጟ⋵᧲ㇱ䈫␹ᄹᎹ ⋵⷏ㇱ䋨▫ᩮ䋩䈪⊒↢䈚䈢䋮䉁䈢ၯ₹⋵ਛㇱ䈱࿾㔡䉅䋬䈠䈱๟ ㄝ䈪ᓸዊ࿾㔡䈱㰱CFF 䈏Ⴧട䈚䈢㗔ၞ䈪⊒↢䈚䈢䋮 ධ㑐᧲䈮䈍䈔䉎 M7 ⚖࿾㔡䈱 30 ᐕ⊒↢⏕₸ 70 %䋨࿾㔡⺞ ᩏᆔຬળ䋬2004䋩䈱ᩮ᜚䈫䈭䈦䈢 5 䈧䈱ⵍኂ࿾㔡䈱䈉䈤䋬䊜䉦䊆䉵䊛⸃䈏䉒䈎䈦䈩䈇䈭䈇 1895 ᐕ⨙ၔ⋵ධㇱ䈱࿾㔡䉕㒰䈒 4 ࿾ 㔡䈮ኻ䈚䈩䈲䋬1894 ᐕ᣿ᴦ᧲੩䋬1921 ᐕ⨙ၔ⋵ධㇱ䋬1987 ᐕ ජ⪲⋵᧲ᣇᴒ䈱 3 ࿾㔡䈪 0.1 bar એ਄䈱ᷫዋ䋬1922 ᐕᶆ⾐᳓ ㆏ઃㄭ䈱࿾㔡䈮ኻ䈚䈩 0.1 bar 䈱Ⴧട䈪䈅䈦䈢䋮 ⊒↢ᐕ. ࿾㔡ฬ. M. 㰱CFF (bars). ෳ⠨ᢥ₂. 1894. ᣿ᴦ᧲੩࿾㔡. 7.0. -0.10. ൎ㑆↰䊶ઁ䋨1999䋩. 1921. ⨙ၔ⋵ධㇱ䈱࿾㔡. 7.0. -0.24. ⍹ㄝ䊶ઁ䋨2010䋩. 1922. ᶆ⾐᳓㆏ઃㄭ䈱࿾㔡. 6.8. +0.10. ⍹ㄝ䊶ઁ䋨2010䋩. 1923. ᄢᱜ㑐᧲࿾㔡. 7.9. -0.02. Matsu'ura. and. Iwasaki (1983)㩷䈭䈬. 2䋮䊂䊷䉺䈍䉋䈶ᚻᴺ ᭽䇱䈭ဳ䈱࿾㔡䈏⊒↢䈜䉎ⶄ㔀䈭ᔕജ႐䈮䈍䈇䈩䋬ฃ䈔ᚻ ஥䈱ᢿጀ䊜䉦䊆䉵䊛䉕઒ቯ䈚䈩⸘▚䈚䈢ǍCFF 䈲ᄢ䈐䈭⺋Ꮕ䉕 ฽䉃䋨଀䈋䈳䋬Toda, 2008; Ishibe et al., 2011䋩䋮䈠䈖䈪ᧄ⎇ⓥ䈪䈲䋬ㆊ෰࿾㔡䈱䊜䉦䊆䉵䊛⸃䋨㒐ἴ⑼ቇᛛⴚ⎇ⓥᚲ䈮䉋䈦䈩᳿ ቯ䈘䉏䈢㑐᧲䊶᧲ᶏ࿾㔡᷹ⷰ✂ቯᏱಣℂ䈮䉋䉎ೋേ䊜䉦䊆䉵䊛 ⸃䋻1979 ᐕ 7 ᦬ 1 ᣣ䌾2003 ᐕ 7 ᦬ 1 ᣣ䋩䉕ฃ䈔ᚻ஥䈱ᢿጀ䊜䉦䊆䉵䊛⸃䈫䈚䈩ᓸዊ࿾㔡䈮ኻ䈜䉎㰱CFF 䉕⸘▚䈚䈢䋮䉁䈢䋬 1885 ᐕએ㒠䈮㑐᧲䈪⊒↢䈚䈢 14 䈱ⵍኂ࿾㔡䈮ኻ䈚䈩ห᭽䈮㰱CFF 䉕⸘▚䈚䋬ᓸዊ࿾㔡䈮ኻ䈜䉎㰱CFF 䈫ኻᲧ䈚䈢䋮. 1930. ർદ⼺࿾㔡. 7.3. +0.22. Kasahara (1957)䈭䈬. 1931. ⷏ၯ₹࿾㔡. 6.9. -0.79. Abe (1974a). 1935. 㕒ጟ࿾㔡. 6.4. -0.22. ᱞየ䊶ઁ䋨1979䋩. 1968. ၯ₹⋵ਛㇱ࿾㔡. 6.1. +0.46. Abe (1975b). 1974. દ⼺ඨፉᴒ࿾㔡. 6.9. +0.03 ~ +0.10. ᧻ፒ䋨1975䋩䋬ᄙ↰ 䋨1976䋩䋬Abe (1978). 1978. દ⼺ᄢፉㄭᶏ࿾㔡. 7.0. +0.29 ~ +0.31. Shimazaki. and. Somerville. (1978,. 1979)䋬ጟ↰䋨1978䋩 1980. દ⼺ඨፉ᧲ᣇᴒ࿾㔡. 6.7. +0.29 ~ +0.33. 1982. ⨙ၔ⋵ᴒ࿾㔡. 7.0. -0.36. ⩵࿾䊶㗇⮮䋨1985䋩. 1984. 㐳㊁⋵⷏ㇱ࿾㔡. 6.8. +0.06 ~ +0.10. ਃ㔕䊶ઁ䋨1985䋩䋬ጊ. 1987. ජ⪲⋵᧲ᣇᴒ࿾㔡. 6.7. -0.35 ~ -0.34. Irikura. (1983),. Takenaka (1987)䈭䈬. 3䋮⚿ᨐ䈫⼏⺰ ㆊ෰䈮⊒↢䈚䈢 30,000୘૛䉍䈱ᓸዊ࿾㔡䈱䊜䉦䊆䉵䊛⸃䈱䈉䈤䋬㰱CFF 䈏 0.1 bar એ਄Ⴧട䈚䈢࿾㔡ᢙ䈲⚂16,000 ୘䈪䈅䈦䈢䋮৻ᣇ䈪䋬0.1 bar એ਄ᷫዋ䈚䈢࿾㔡ᢙ䈲⚂ 8,000 ୘䈪䈅䈦䈢䋮㰱CFF 䈏Ⴧട䈚䈢࿾㔡䈱ഀว䈏ᄙ䈎䈦䈢㗔ၞ䈲䋬30 km એᵻ 䈪䈲દ⼺䉕฽䉃㕒ጟ⋵᧲ㇱ䈫␹ᄹᎹ⋵⷏ㇱ䋨▫ᩮ䋩䈪䈅䈦䈢䋮 ᷓ䈘 30~100 km 䈱࿾㔡䈮ኻ䈚䈩䈲⨙ၔ⋵ධ⷏ㇱ䈫᧲੩ḧർㇱ䈎䉌㌑ሶ䈮⥋䉎㗔ၞ䈪䈅䈦䈢䋮䈖䉏䉌䈱㗔ၞ䈪䈲ᧄ㔡ᓟ䈮࿾ 㔡ᵴേ䈏ᵴ⊒ൻ䈚䈩䈍䉍䋬ᧄ⎇ⓥ䈲╙৻ㄭૃ⊛䈮ᧄ㔡ᓟ䈱࿾ 㔡ᵴേ䉕⦟䈒⺑᣿䈜䉎䋮ߒ߆ߒߥ߇ࠄ㧘⨙ၔ⋵ർㇱ߆ࠄ⑔ፉ ⋵ධㇱߩᵻㇱߦ߅޿ߡᵴ⊒ൻߒߚᱜᢿጀဳߩ࿾㔡ߥߤ㧘ᧄ 㔡೨ߩ࿾㔡ᵴേ߇ૐ⺞ߢ㔡Ḯࡔࠞ࠾࠭ࡓߩᖱႎ߇ਇචಽߥ 㗔ၞߦኻߒߡߪ㧘ᧄᚻᴺߩㆡ↪ߪ࿎㔍ߢ޽ࠆ㧚ᧄᚻᴺߩ♖ ᐲะ਄ߦߪ㧘ᓸዊ࿾㔡ߩࡔࠞ࠾࠭ࡓ⸃ߩలታ㧔ᔕജ႐ߩ⹦ ⚦ߥ⸃᣿㧕߇ᔅ㗇ߢ޽ࠆ㧚. ⑼䊶ᄙ↰䋨1985䋩 ጊ↰䋨1988䋩, Okada and Kasahara (1990). ⻢ㄉ䋺ᧄ⎇ⓥ䈪䈲䋬ᵤᵄᵄᒻ䉟䊮䊯䉜䊷䉳䊢䊮䈮䉋䉍ផቯ䈘䉏䈢 ᧲ർᴒ࿾㔡䈱㔡Ḯᢿጀ䊝䊂䊦䋨Satake et al., submitted䋩䋬᳇⽎ ᐡ৻రൻ㔡Ḯ䉦䉺䊨䉫䈭䉌䈶䈮䋬㒐ἴ⑼ቇᛛⴚ⎇ⓥᚲ䈮䉋䉎䊜䉦䊆䉵䊛⸃䉕૶↪䈘䈞䈩㗂䈇䈢䋮䉁䈢䋬䊜䉦䊆䉵䊛⸃䈱ផቯ䈮䈲 HASH (Hardebeck and Shearer, 2002)䉕䋬㰱CFF 䈱⸘▚䈮䈲 Okada (1992)䉕૶↪䈘䈞䈩㗂䈇䈢䋮䈭䈍䋬ᧄ⎇ⓥ䈲ᐔᚑ 24 ᐕ ᐲ⑼ቇᛛⴚᝄ⥝⾌䇸ㇺᏒ䈱⣀ᒙᕈ䈏ᒁ䈐⿠䈖䈜ỗ↟ἴኂ䈱シ ᷫൻ䊒䊨䉳䉢䉪䊃䇹䈮䈍䈔䉎䇸㚂ㇺ࿤䈪䈱ਛዊ࿾㔡䈫ᄢ࿾㔡䈱 ⊒↢ㆊ⒟䈱㑐ଥ䈱⸃᣿䇹䈱৻Ⅳ䈫䈚䈩ታᣉ䈘䉏䈢䋮. - 160 -.

(2)