䈖䈉䈋䈇䊐䉤䊷䊤䊛╙ 㪈㪈 ภ㩷 㪆㩷㪉㪇㪇㪊㪅㪈㩷Ᏹᤨᓸേ䈮ၮ䈨䈒ጤᚻ⋵䊶㔑⍹⋆࿾䈱࿾⋚᭴ㅧផቯ
ESTIMATION OF UNDERGROUND STRUCTURE IN SHIZUKUISHI BASIN BASED ON THE
MICROTREMOR MEASUREMENTS AND ANALYSISᄢⷺᕡ㓶*䊶ਛ᧛㩷 ᤯**Tsuneo OHSUMI㩷 and Susumu NAKAMURAThe Northern Iwate Prefecture earthquake happened at September 3,1998 and has a similar
characteristics with The 1999 CHI-CHI earthquake, Taiwan. First of all, the damages such as
slope failures around epicentral region and the failure of underground structures due to thevertical dislocation of ground caused by the fault movement are described. Furthermore, thestrong motion records were observed around the epicentral region. The maximum acceleration
is more than 700gal. The characteristics of the seismic records were influenced by the fault
mechanism as dip slip. Hereby, in this work, estimation of underground structure based on the
microtremor measurements and analysis were conducted in Shizukuishi basin so as toexamine the effectiveness of approach.

㩷 Key Words䋺㩷 㩷 1998 Northern Iwate Prefecture earthquake, 㩷 seismic damages, seismicrecords, SPAC method, kinematic source model㪈㪅㩷㩷䈲䈛䉄䈮㩷䉒䈞䈩䇮㔑⍹⋆࿾䈱᧲⷏ᣇะ䈱࿾⋚᭴ㅧ䉕ᛠី䈜䉎䈢䉄䇮11998 ᐕ 9 ᦬ 3 ᣣ䈮⊒↢䈚䈢ጤᚻ⋵ർㇱ࿾㔡䈲䇮ᭂ㔡Ḯὐ᷹ⷰ䉕 12 ὐ䈪ታᣉ䈚䈢䇯ၞㄭற䈪㔡ᐲ 6 ᒙ䉕⸥㍳䈚䇮1999 ᐕ 9 ᦬ 21 ᣣ䈮บḧ䈪⊒↢ 䈚䈢㓸 㓸࿾㔡 䈫ห ᭽ 䈮ૐ ⷺ ㅒ ᢿ ጀ 䉕㔡Ḯ ᯏ ᭴ 䈫䈚䇮࿾⴫㪉㪅㩷㩷㔑⍹⋆࿾䈮䈍䈔䉎࿾㔡േ․ᕈ㩷㕙䈮ᢿጀ䈱ᓇ㗀䈫⠨䈋䉌䉏䉎ᲑᏅ䈱⊒↢ 1) ╬䈱․ᓽ䉕᦭䈚䈩㔡 Ḯ ㄭ ற 䈱 Nagayama(JMA)䇮Shizukuishi(JMA)䇮䈘

䈇䉎䇯บḧ䊶㓸㓸࿾㔡䈪䈲ᢿ ጀㄭற䈪䈱ᒝ 㔡⸥㍳䈮⴫㕙 ᵄ䉌䈮 K-net 䈮䉋䉎㔡Ḯ⷏ᣇ䈱↰ᴛḓ Tazawako(K-net)䇮㔡

䈱ᓇ㗀䈫⠨䈋䉌䉏䉎㐳๟ᦼᚑಽ䈱ථ⿧䈏⹺䉄䉌䉏䇮ᢿጀ䉋䉍Ḯ᧲ධᣇะ䈱⋓ጟᏒ Morioka(K-net)䈱 4 ࿾ὐ䈪᷹ⷰ䈘䉏

20km ⒟ᐲ㔌䉏䈢บਛ᷼䈮䈍䈔䉎♧Ᵽ䉺䊮䉪䈱䉴䊨䉾䉲䊮䉫䈢ᒝ㔡⸥㍳䈱᳓ᐔ 2 ᚑಽ䉋䉍᳞䉄䈢䊔䉪䊃䊦䊐䊷䊥䉣䉴䊕䉪䊃䈮䉋䉎ⵍኂ䉕䉅䈢䉌䈚䈢䈫ផቯ䈘䉏䈩䈇䉎2) 䇯ጤᚻ⋵ർㇱ࿾㔡䊦2) 䈱 Ყ セ 䉕 ࿑ 䋭 㪈䈮␜䈜䇯䈖䉏䉋䉍䇮㔡Ḯㄭற䈱䈮䈍䈇䈩䉅䇮㔡Ḯ䉋䉍⚂ 10km 㔌䉏䈢㔑⍹⋆࿾ౝ䈪䈱᷹ⷰ⸥

Nagayama(JMA)䈪䈲 3.4Hz䇮1.7Hz 䈮ථ⿧๟ᵄᢙ䈏⹺䉄㍳䈮⴫㕙ᵄ䈱ᓇ㗀䈫ផቯ䈘䉏䉎ᵄ⟲䈏⹺䉄䉌䉏䈩䈇䉎䇯䈖䈱䉌䉏䉎䈏䇮৻ᣇ䇮Sizukuishi(JMA)䈪䈲 0.4Hz ㄭற䈪ૐ๟᭽䈮䇮ጤᚻ⋵ർㇱ࿾㔡䈲࿾㔡ⷙᮨ䈲⇣䈭䉎䉅䈱䈱㓸㓸࿾㔡ᵄᢙᏪၞ䈮ථ⿧๟ᵄᢙ䈏䉂䉌䉏䇮䈖䈱๟ᵄᢙᏪၞ䈱䉴䊕䉪䊃䈫㘃ૃ䈱․ᓽ䉕᦭䈚䈩䈇䉎䇯䈖䈱䈖䈫䈎䉌䇮㔑⍹⋆࿾䈮䈍䈇䈩䈠䈱᭽䈭ᵄേ䈱⊒↢䊶વ᠞ᯏ᭴䉕ᛠី䈜䉎䈖䈫䈲䇮੹ᓟ㔡Ḯᢿጀㄭற䈮䈍䈔䉎ฦ⒳᭴ㅧ‛䈱⠴㔡⸳⸘䉕ⴕ䈉䈢䉄䈮ᔅⷐ䈭౉ ജ ࿾ 㔡 േ 䉕⹏ ଔ 䈜䉎਄ 䈪㊀ ⷐ 䈪䈅䉎䈫⠨ 䈋䉌䉏 䉎䇯৻ᣇ䇮㔑⍹⋆࿾䈪᷹ⷰ䈘䉏䈢࿾㔡⸥㍳䈱⊒↢䊶વ᠞ᯏ᭴䉕ᛠី䈜䉎䈢䉄䈮䈲䇮᷹ⷰ࿾ὐ䉕฽䉃㔑⍹⋆࿾䈱࿾⋚᭴ㅧ䈏ᔅⷐ䈫䈭䉎䈏䇮․䈮ᷓጀ࿾⋚᭴ㅧ䈱⹦⚦䈭䊂䊷䉺䈲ᓧ䉌䉏䈩䈇䈭䈇䇯䈖䈖䈪䈲䇮㔑⍹⋆࿾䈮䈍䈔䉎ᷓጀ࿾⋚䉕ᛠី䈜䉎䈢䉄䇮Ᏹᤨᓸേ᷹ⷰ䉕ታᣉ䈚䇮䈠䈱⚿ᨐ䈮ၮ䈨䈐ផቯ䈚䈢࿾⋚᭴ ㅧ䈮䈧䈇䈩ႎ๔䉕ⴕ䈉䇯࿾⋚᭴ㅧ䈲 2 ὐหᤨ᷹ⷰ䈮䉋䉍᳞䉄䈢ⓨ 㑆 ⥄ Ꮖ⋧ 㑐㑐 ᢙ 䈮ၮ䈨䈒૏ ⋧ ㅦ ᐲ․ ᕈ䉋䉍ផቯ 䈚䈢䇯૬*㩷**ਛᄩ⎇ⓥᚲ㩷 ✚วᛛⴚ㐿⊒ㇱᣣᧄᄢቇ㩷 Ꮏቇㇱ㩷 ࿯ᧁᎿቇ⑼࿑䋭㪈㩷 䊔䉪䊃䊦䊐䊷䊥䉣䉴䊕䉪䊃䊦䈱Ყセ㩷㪈㪌㩷Ᏹᤨᓸേߦၮߠߊጤᚻ⋵࡮㔑⍹⋆࿾ߩ࿾⋚᭴ㅧផቯ!
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࿑䋭㪉㩷 ࿾㔡േ䈱᳓ᐔ㕙ౝ䈱㩷㩷 㩷 㩷 㩷 㩷 ㅦᐲ䉥䊷䊎䉾䊃㩷࿑䋭㪊㩷 㕖ቯᏱ䉴䊕䉪䊃䊦㩿㪜㪮 ᚑಽ㪀!

䊦ᝄ ᏷ 䈲㔡 Ḯ ㄭ ற 䉋䉍ᄢ 䈐䈭୯ 䈫䈭䈦䈩䈇䉎䇯ᰴ 䈮䇮㔑 ⍹⋆࿾ౝ䈱 Shizukuishi(JMA)䈪᷹ⷰ䈘䉏䈢⸥㍳䉕ᢙ୯Ⓧಽ䈜!

䉎䈖䈫䈮䉋䉍ᓧ䉌䉏䈢ㅦᐲᚑಽ䈱᳓ᐔ㕙ౝ䈱䉥䊷䊎䉾䊃䉕࿑䋭㪉 䈮␜䈜䇯䈖䉏䉋䉍䇮࿾㔡ᵄ೔㆐ᓟ䈱 10 ⑽(࿑ਛ⎕✢)એ㒠䈱㔡േᣇะ䈲᧲⷏ᣇะ䈮ථ⿧䈜䉎௑ะ(࿑ਛᵄ✢)䈏⹺䉄䉌䉏!

䉎䇯䈠䈱 Shizukuishi(JMA)䈮䈍䈔䉎ૐ๟ ᵄᢙᏪၞ 䈱࿾ 㔡േ․ᕈ䉕ᛠី䈜䉎䈢䉄䇮EW ᚑಽ䈮㑐䈜䉎㕖ቯᏱ䉴䊕䉪䊃䊦䉕࿑䋭㪊 䈮␜䈜䇯䈖䉏䉋䉍䇮࿾㔡ᵄ䈱೔㆐䉋䉍 10 ⑽๟ㄝએ㒠䇮!

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๟ᦼ 1 ⑽એ਄䈱ᚑಽ䈮䈲ಽᢔᕈᵄേ䇮䈜䈭䉒䈤⴫㕙ᵄᚑಽ
䈱․ᕈ䈏㗼⪺䈮⃻䉏䈩䈇䉎䇯䈠䈱․ᕈ䈲๟ᦼ 1.1-1.2 ⑽๟ㄝ䈮䈩ᦨ䉅㗼⪺䈪䈅䉎䈏䇮๟ᦼ 3 ⑽ㄭற䈮䉅䈠䈱ᓇ㗀䈏⹺䉄䉌!

䉏䉎䇯࿑ 䋭㪈 䈮␜ 䈚䈢䊐䊷䊥䉣䉴䊕䉪䊃䊦䉋䉍䇮㔡 Ḯ ㄭ ற 䈮䉅
0.5H Z 䈮Ყセ⊛ఝ൓䈭ᚑಽ䈏⷗䉌䉏䉎䈖䈫䈎䉌䇮๟ᦼ 3 ⑽ㄭ!

ற䈱ᚑಽ䈲㔡 Ḯ䈱ᓇ㗀䉕ฃ 䈔䈩䈇䉎䉅䈱䈫ផቯ䈘䉏䉎䇯䈇䈝䉏䈮䈚䈩䉅䇮Sizikuishi(JMA)䈪᷹ⷰ䈘䉏䈢࿾㔡േ䈱㐳๟ᦼᚑಽ䈲⴫㕙ᵄᚑಽ䈪䈅䉐䈉䈫ផቯ䈘䉏䉎䇯!

㪊㪅㩷㩷ᓸേ᷹ⷰ䈱᭎ⷐ㩷!ᷓㇱ࿾ਅ᭴ㅧ䉕ᛠី䈜䉎䈢䉄䈱䉝䊧䊷᷹ⷰ䈫㔑⍹⋆࿾䈱䈾䈿ਛᄩ䈮䈍䈔䉎᧲⷏ᣇะ䈱࿾ጀ᭴ㅧ䉕ᛠី䈜䉎䈢䉄䈱න࿑䋭㪋㩷 㔑⍹⋆࿾䈮䈍䈔䉎ᓸേ᷹ⷰὐ䈱㈩⟎ὐ᷹ⷰ䉕 1999 ᐕ 11 ᦬ 5 ᣣ䈎䉌 6 ᣣ䈮䈎䈔䈩ታᣉ䈚䈢䇯ฦ

᳓ᐔ 2 ᚑಽ (NS䇮EW)䈍䉋䈶਄ਅേᚑಽ䈱 3 ᚑಽ䉕ኻ⽎䈫!

䈚䈢䇯ฦὐ䈪ᓧ䉌䉏䈢᳓ᐔ 2 ᚑಽ䉋䉍▚಴䈚䈢䊔䉪䊃䊦䉴䊕䉪䊃䉝䊧䊷᷹ⷰ 䈲⋆࿾ౝ 䈱ᒝ 㔡᷹ⷰὐㄭற 䈱ᷓㇱ࿾ਅ ᭴ ㅧ䊦䈫਄ਅേᚑಽ䈱䉴䊕䉪䊃䊦Ყ(H/V 䉴䊕䉪䊃䊦)䈱ථ⿧๟ᦼ䈮᷹ⷰ䈱᷹ቯ૏⟎䈲࿑㧙 䈮␜䈚䈢䈫䈍䉍䈪䈅䉎䇯䉕ផ ቯ䈜䉎䈢䉄䇮㔑⍹ ✚ว ㆇേ႐ 䈪ታᣉ 䈚䈢䇯ᷓㇱ ࿾ ⋚ ᭴ၮ䈨䈐䇮᧲⷏ᣇะ䈱࿾ጀ᭴ㅧ䈮䈧䈇䈩ᬌ⸛䉕ⴕ䈦䈢䇯ㅧ䈱ផቯ䈲䇮Aki 3) 䈮䉋䉍ឭ᩺䈘䉏䈩ᦨㄭ䉋䈒↪䈇䉌䉏䉎䉋䈉䈮䈭䈦䈩䈇䉎ห৻౞๟਄䈱 2 ὐ䈪䈱਄ਅേᚑಽ䈱หᤨ᷹ⷰ⸥㍳䈮ၮ䈨䈒ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙᴺ(SPAC ᴺ) 4,5) 䈮䉋䈦䈩⴫㕙㪋㪅㩷㩷ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙᴺ㩿㪪㪧㪘㪚 ᴺ㪀䈮䉋䉎࿾⋚᭴ㅧ䈱ផቯ㩷ᵄ䈱૏⋧ㅦᐲ䉕▚಴䈚䇮᷹ⷰ䊶ℂ⺰૏⋧ㅦᐲ․ᕈ䈏ᢛว䈜䋨㪈䋩㩷 ૏⋧ㅦᐲ䈱ផቯ䉎䉋䈉䈮䇮࿾⋚᭴ㅧ䉕⹜ⴕ㍲⺋⊛䈮᳞䉄䉎䈫䈇䈉ᵹ䉏 6) 䈪ታᣉ䈚䈢䇯᷹ቯ䈮㓙䈚䈩䇮䉝䊧䊷ඨᓘ 150䌭䈫䈚䇮౞๟਄䈱 5 ὐ䉕
⒖േ䈘䈞䈩᷹ቯ䈚䈢䇯නὐ᷹ⷰ䈲࿑㧙 䈮␜䈜㔑⍹⋆࿾䈱䈾䈿ਛᄩ䈱᧲⷏᷹✢䈮ᴪ䈦䈢 12 ࿾ὐ䈪ታᣉ䈚䈢䇯㩷 ᷹ቯ䈲䉰䊷䊗ဳ䈱ㅦᐲ⸘(᧲੩᷹ᝄ⵾䋺VSE-15D)䉕↪䈇䇮䉰䊮䊒䊥䊮䉫๟ᵄᢙ 100Hz౞ᒻ䉝䊧䊷਄䈍䉋䈶ਛᔃὐ䈱 2 ὐ X䇮Y ᷹ⷰ䈘䉏䈢⸥㍳䈮䉅䈫䈨䈐౞ᝄേᢙ㱥 䈗䈫䈮ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ 㱝 (㱥) 䉕ᰴᑼ䈮䉋䉍▚಴䈜䉎䇯ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ 㱝 (㱥) 䈲䇮౞ᒻ䉝䊧䊷਄䈱 i ὐ䈫ਛᔃὐ㑆䈱ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ䈲 2 ὐ䈪᷹ቯ䈘䉏䈢⸥㍳䈱䍘䍩䍎䍸䍻䍛䈱ታᢙㇱ䈫䈚䈩ᓧ䉌䉏䉎ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ䉕䈮䈩 AD ᄌ឵䈘䉏䈢䊂䉳䉺䊦䊂䊷䉺䉕⋥ធ PC 䈪⸥㍳䈜䉎ⵝਛᔃὐ䈎䉌౞ᒻ䉝䊧䊷਄䈱ฦ᷹ὐ䈮ኻ䈜䉎ᣇ૏ᐔဋ䈜䉎䈖䈫⟎(SPC-35N)䉕↪䈇䈩ታᣉ䈚䈢䇯䉁䈢䇮䈇䈝䉏䈱࿾ὐ䈪䉅ㅦ㑆䈱䉪䊨䉴䉴䊕䉪䊃䊦䇮 SX ,i (㱥,㱔)䋬 S Y ,i (㱥) 䈲౞๟਄䈱᷹ὐ iᐲᚑಽ䉕ኻ⽎䈫䈚䇮3 ಽ㑆䈱᷹ቯ䉕ታᣉ䈚䈢䇯ฦ᷹ⷰὐ䈪䈲㪈㪍㩷䈪▚಴䈚䈢䇯䈖䈖䈪䇮 S XY ,i (㱥,㱔) 䈲౞๟਄䈱᷹ὐ i 䈫ਛᔃὐ䈫ਛᔃὐ䈮䈍䈔䉎䊌䊪䊷䉴䊕䉪䊃䊦䉕␜䈚䈩䈇䉎䇯䈖䈉䈋䈇䊐䉤䊷䊤䊛╙ 㪈㪈 ภ㩷 㪆㩷㪉㪇㪇㪊㪅㪈㩷r = ( 2p ) -1 ò

2p0

Re al [S xy ,i (w ,q ) ]

dq
1/ 2

[S (w ,q )S (w ) ]x ,i䈩⭯䈒䈭䉎௑ะ䈮䈅䉎䈖䈫䈏ಽ䈎䉎䇯࿑䋭㪍 䈮␜䈚䈢૏⋧ㅦᐲ䈱ᐔဋಽᢔᦛ✢䈮⌕⋡䈜䉏䈳๟(1)

ᦼ 1.5 ⑽䉋䉍 1.2 ⑽䈮䈎䈔䈩૏⋧ㅦᐲ䈱ૐਅ䈏ᄢ䈐䈇䈖䈫䈏ಽ䈎䉎䇯䈖䈱䈖䈫䈎䉌䇮ᦨᷓㇱ䈱࿾ጀ(⿥⧰㋕⾰ጤጀ)䈱 S ᵄY ,iㅦᐲ䈲䇮࿑䋭㪍 䈮䈍䈔䉎๟ᦼ 1.7 ⑽䈎䉌 2.0 ⑽䉁䈪䈾䈿৻ቯ௑ะ 䉕␜ 䈜૏ ⋧ㅦᐲ 䈱୯䉋䉍ᣧ 䈇ㅦᐲ 䇮2000m/s 䈫઒ቯ䈚䈢䇯䉁䈢䇮࿑䋭㪍 䉋䉍ᦨ⴫ጀ(㞲ᣂ਎ጀ)䈱 S ᵄㅦᐲ䈲⍴๟ᦼ஥䈱૏⋧ㅦᐲ․ᕈ䈮ၮ䈨䈐 800m/s 䈫઒ቯ䈚䈢䇯࿑䋭㪎 䉋䉍⴫ጀ䈫ᦨᷓㇱ䈱ጀ䈫䈱㑆䈮ਛᣂ਎ጀ䈫ẋᣂ਎ጀ䈱 2 ጀ䈏ሽ࿷䈚䈩䈇䉎䈏䇮䈖䈖䈪䈲䇮⴫ጀ䈫ᦨᷓㇱ䈱ጀ䈱ᐔဋ⊛䈭
1400m/s 䉕ਔጀ䈱 S ᵄㅦᐲ䈫઒ቯ䈚䈢䇯䈘䉌䈮䇮䈠䉏䈡䉏䈱ጀ䈱⾰㊂ኒᐲ䈲⴫㪄 㪈 䈱᭽䈮઒ቯ䈚䈢䇯䈠䉏䉌䈱઒ቯ䈱ၮ䈨䈇䈩䈪䇮ฦጀ䈱ጀෘ䈘䉕ᄌൻ䈘䈞䈭䈏䉌䇮Rayleigh ᵄ䈱ℂ⺰࿑䋭㪌㩷 ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ㩷૏⋧ㅦᐲ䉕▚಴䈚䇮᷹ⷰ䈮䉋䉍ᓧ䉌䉏䈢૏⋧ㅦᐲ䈱ಽᢔᦛ✢㵘䈖䈱ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ 㱝 (㱥) 䈲䇮᷹ቯ⸥㍳䉋䉍᛽಴䈚䈢䈫䈱Ყセ䉕ⴕ䈦䈢䇯⴫䋭㪈 䈮䈲䇮ਔ⠪䈏ᦨ䉅ᢛว䈜䉎㓙䈱ጀ

81.92 ⑽඙㑆䈮䈧䈇䈩䇮᛽಴㐿ᆎᤨೞ䉕 5 ⑽䈨䈧䈝䉌䈚䈭䈏䉌 8 ඙㑆䈮䈧䈇䈩▚಴䈚䈢䇯䈠䈱㓙䇮ฦ䉴䊕䉪䊃䊦䈲 0.2Hz 䈱䊋䊮䊄᏷䉕᦭䈜䉎 Parzen Window 䈮䉋䉍ᐔṖൻಣℂ䉕ⴕ䈉䈖䈫䈮䉋䉍▚಴䈚䈢䇯䈖䈖䈪ᓧ䉌䉏䈢๟ᵄᢙ䈫ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ䈱㑐ଥ䉕࿑䋭㪌 䈮␜䈜䇯
ᑼ(1)䈱ฝㄝ䈮␜䈜 2 ὐ㑆䈱ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ䈲䇮2 ὐ䈪᷹ቯ䈘䉏䈢ᓸേ䈮 2 ὐ㑆䉕વ᠞䈜䉎 Rayleigh ᵄ䈱ၮᧄ䊝䊷ෘ䉕␜䈚䇮࿑䋭㪍 䈮䈲䈠䈱㓙䈱૏⋧ㅦᐲ䈍䉋䈶⟲ㅦᐲ䈱ℂ⺰
ಽᢔᦛ✢䉅ว䉒䈞䈩␜䈜䇯࿑䋭㪍 䈮␜䈜᭽䈮๟ᦼ 1.5 ⑽䈎䉌
0.8 ⑽䈮䈎䈔䈩䇮ਔ⠪䈱૏⋧ㅦᐲ䈱ಽᢔᦛ✢䈲䉋䈒৻⥌䈚䈩䈇䉎䈖䈫䈏ಽ䈎䉎䇯ᓸേ䈱䉝䊧䊷᷹ⷰ䈪䈲䇮䉝䊧䊷ඨᓘ䈫䈚䈩 150m 䈱 1 ⒳㘃䈱᷹ቯ䈪䈅䈦䈢䈢䉄䇮⴫䋭㪈 䈮␜䈜࿾⋚᭴ㅧ䊝䊂䊦䈱䈉䈤ㅦᐲ᭴ㅧ䈮䈧䈇䈩䈲઒ቯ䈱ᬌ⸽䉕ⴕ䈦䈩䈇䈭䈇䇯䊄䈏ఝ൓䈮฽䉁䉏䈩䈇䉎䈫䈱઒ቯ䈱ၮ䈪䇮╙ 1 ⒳ 0 ᰴ䈱䊔䉾䉶䊦㑐ᢙ䈱ቯ⟵䉋䉍ᰴᑼ䈱䉋䈉䈮⴫䈜䈖䈫䈏䈪䈐䉎䇯UZ

J 0 rk§ Z r ·¸¸
J 0 ¨¨©c f ¹(2)䈖䈖䈪䇮 r 䈲䉝䊧䊷ඨᓘ䇮 c (f ) 䈲๟ᵄᢙ f 䈮ኻ䈜䉎૏⋧ㅦᐲ䉕⴫䈜䇯૏⋧ㅦᐲ䈲䇮࿑䋭㪌 䈮␜䈚䈢ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ䈮ኻᔕ䈜䉎╙ 1 ⒳ 0 ᰴ䈱䊔䉾䉶䊦㑐ᢙ䈱䉝䊷䉩䊠䊜䊮䊃(= 㱥r / c ( f ))䈫૏⋧ㅦᐲ䈱㑐ଥ䉋䉍▚಴䈚䈢䇯䈠䈱㓙䇮࿑䋭㪌 䉋䉍๟ᵄᢙ 0.5Hz(2.0sec)䈎䉌⚂ 2.5Hz(0.4sec)䈱㑆䉕᦭ല๟ᵄᢙᏪ䈫䈚䈢䇯䈖䈖䈪ᓧ䉌䉏䈢૏⋧ㅦᐲ䈫๟ᦼ䈱㑐ଥ䉕࿑䋭㪍 䈮␜䈜䇯࿑ਛ䈮䈲䇮8 ඙㑆䈮䈧䈇䈩▚಴䈚䈢ⓨ㑆⥄Ꮖ⋧㑐㑐ᢙ䈮䉋䉍᳞䉄䈢૏⋧ㅦᐲ䈱ᐔဋ୯(࿑ਛ䂾ශ)䈫䈠䈱㫧㱟඙㑆䉅ว䉒䈞䈩⎕✢䈪␜䈚䈢䇯䉁䈢 0.7 ⑽䈎䉌 0.4 ⑽䉁䈪䈲䈳䉌䈧䈐䈏ᄢ䈐䈇䈖䈫䈎䉌࿑䈱䉋䈉䈮 0.7 ⑽䉋䉍⍴๟ᦼ஥䈲䉦䉾䊃䈚䈢䇯࿑࿑䋭㪍㩷 ᷹ⷰ䊶ℂ⺰૏⋧ㅦᐲ․ᕈ㩷䈮␜䈜᭽䈮䇮૏⋧ㅦᐲ䈲⚂ 1300m/s 䈎䉌 800m/s 䈱㑆䈪ᄌൻ䈚䈩䈇䉎䇯
䋨㪉䋩㩷 ࿾⋚᭴ㅧ䈱ផቯ࿾⋚᭴ㅧ䈲䇮ᓧ䉌䉏䈢૏⋧ㅦᐲ䈱ಽᢔᦛ✢䈮ၮ䈨䈇䈩ផቯ䉕ⴕ䈉䇯䈖䈖䈪䇮㔑⍹⋆࿾䈮䈍䈔䉎᧲⷏ᣇะ䈱࿾⾰᭴ㅧ䈲䈍䈍䉃䈰࿑䋭㪎 8) 䈮␜䈜䈫䈍䉍䈪䈅䉎䇯࿑ਛ䈮␜䈜䉋䈉䈮⴫ጀ䈮䈲╙ 4 ♿䈱ၸⓍጀ䈏ሽ࿷䈚䇮䈠䉏એᷓ䈮䈲㞲ᣂ਎એ೨䈱Ყセ⊛ၷ䈇ጤ⾰ጀ䈱䈉䈤㞲ᣂ਎ጀ䈏⷏஥䈎䉌᧲஥䈮ะ䈎䈦㪈㪎㩷Ᏹᤨᓸേߦၮߠߊጤᚻ⋵࡮㔑⍹⋆࿾ߩ࿾⋚᭴ㅧផቯ

⴫䋭㪈㩷 ផቯ䈚䈢࿾⋚᭴ㅧ䊝䊂䊦ጀᢙጀෘ(m)

S ᵄㅦᐲ(m/s)

⾰㊂ኒᐲ(t/m3)

1400

800

2.0

2

400

1400

2.33

㩷

2000

2.5

ข 䈦䈢㐳 ๟ ᦼ஥ (࿑ਛ 䃂)䈫⍴ ๟ ᦼ஥ (࿑ਛ 䂾)䈱ථ⿧๟ᦼ䈫᷹ὐ 1 䉋䉍䈱᳓ᐔ〒㔌䈫䈱㑐ଥ䉕࿑䋭㪐 䈮␜䈜䇯࿑䋭㪐 䉋䉍䇮㐳๟ᦼ஥䈱ථ⿧䈜䉎๟ᦼ䈲㔑⍹⋆࿾䈱⷏஥䈎䉌᧲஥䈮ะ䈎䈦䈩ૐਅ䈜䉎௑ะ䈏⹺䉄䉌䉏䇮䈍䈍䉃䈰࿑䋭㪎 䈱࿾⾰❑ᢿ᭴ㅧ䈎䉌ផ᷹䈜䉎 S ⎕ㅦᐲ᭴ㅧ䈫⺞๺䈚䈩䈇䉎䇯䉁䈢䇮䉝䊧䊷᷹ⷰὐ䈮ㄭ䈇᷹ὐ 5䇮6 䈪䈲䇮ਇ቟ቯ䈪䈲䈅䉎䈏๟ᦼ 3.0 ⑽ઃ
ㄭ䈮䉅ථ⿧๟ᦼ䈏⹺䉄䉌䉏䉎䇯䈠䈱ᓸേ䈱ථ⿧๟ᦼ䈲䇮⴫䋭㪈 䈮␜䈚䈢࿾⋚᭴ㅧ䊝䊂䊦䈮ၮ䈨䈒 S ᵄ䈱㋦⋥౉኿䈮ኻ䈜䉎
1 ᰴ࿕᦭๟ᦼ⚂ 3.0 ⑽䈫䈍䈍䉃䈰ኻᔕ䈚䈩䈇䉎䇯䈘䉌䈮䇮᷹ὐ
1 䈎䉌᷹ὐ 9 䈮䈍䈔䉎 H/V 䉴䊕䉪䊃䊦䈮䈲 1.2 ⑽ㄭற䈮䉅䉒䈝䈎䈮ථ⿧䈏⹺䉄䉌䉏䉎䇯䈖䉏䉌䈱․ᕈ䈱᦭ᗧᕈ䈍䉋䈶ᵄേવ ᠞ ․ ᕈ 䈫䈱㑐 ଥ 䉕᣿ 䉌䈎䈮䈜䉎䈢䉄䇮੹ ᓟ ࿾ 㔡 ᵄ 䈱વ ᠞⸃ᨆ䈭䈬䉕ⴕ䈉ᔅⷐ䈏䈅䉎䇯࿑䋭㪎㩷 㔑⍹⋆࿾䈱࿾⾰᭴ㅧ䊝䊂䊦㩷㪌㪅㩷㩷㪟㪆㪭 䉴䊕䉪䊃䊦Ყ䈱․ᕈ㩷㩷 䈖䈖䈪䈲䇮࿑䋭㪋 ਛ䈱㔑⍹⋆࿾䈱ਛᄩㇱ䈮䈍䈔䉎᧲⷏᷹✢䈮ᴪ䈦䈢 12 ࿾ὐ䈱ᓸേ᷹ⷰ⸥㍳䉕↪䈇䈩▚಴䈚䈢᳓ᐔᚑಽ䈫㋦⋥ᚑಽ䈱䊐䊷䊥䉣䉴䊕䉪䊃䊦Ყ(H/V 䉴䊕䉪䊃䊦)䉋䉍ᓧ䉌䉏䉎ථ⿧๟ᦼ 䈮ၮ䈨䈐䇮ฦ ࿾ὐ䈮䈍䈔䉎࿾⋚䈱࿕᦭ ๟ ᦼ䈱ផቯ䉕ታᣉ䈚䈢䇯䈖䈖䈪䇮᳓ᐔᚑಽ䈲᳓ᐔ 2 ᚑಽ(NS䇮EW)࿑䋭㪐㩷 㩷 ථ⿧๟ᦼ䈫᷹ⷰ࿾ὐ䈱㑐ଥ㩷㪍㪅㩷㩷䈅䈫䈏䈐㩷䈱䊔䉪䊃䊦䉴䊕䉪䊃䊦 2) 䈫䈚䈩▚಴䈚䈢䇯䉁䈢䇮H/V 䉴䊕䉪䊃䊦ጤ ᚻ ⋵ ർㇱ࿾ 㔡 䈮䉋䉎㔑⍹ ⋆ ࿾ 䈪ⷰ ᷹䈘䉏䈢࿾㔡േ䈱․䈲䇮᷹ቯ⸥㍳䉋䉍᛽಴䈚䈢 81.92 ⑽඙㑆䈮䈧䈇䈩䇮᛽಴㐿ᆎᕈ 䉕᣿ 䉌䈎䈮䈜䉎䈢䉄䈮ᔅ ⷐ 䈭࿾ ⋚ ᭴ ㅧ 䉕䇮Ᏹ ᤨ ᓸ േ䈱․ᤨೞ䉕 5 ⑽䈨䈧䈝䉌䈚䈭䈏䉌 8 ඙㑆䈮䈧䈇䈩䇮0.2Hz 䈱䊋䊮ᕈ䈮ၮ䈨䈐ផቯ䈚䈢䇯䈚䈎䈚䇮䉝䊧䊷᷹ⷰ䈮䈩䉝䊧䊷䉰䉟䉵䈱䊄᏷䉕᦭䈜䉎 Parzen Window 䈮䉋䉍ᐔṖൻಣℂ䉕ⴕ䈉䈖䈫䈮⇣䈭䉎᷹ቯ䉕ታᣉ䈚䈩䈇䈭䈇䈢䉄䇮ᷓጀ䊶ᵻጀ࿾⋚᭴ㅧ䈮䈧䉋䉍▚಴䈚䈢䇯㩷 ฦ࿾ὐ䈮䈍䈔䉎 8 ඙㑆䈱 H/V 䉴䊕䉪䊃䊦䉕࿑䋭㪏 䈮ᵄ✢䈪␜䈜䇯࿑䈮䈲䇮䈠䉏䉌䈱ᐔဋ H/V 䉴䊕䉪䊃䊦(ታ✢)䉅ว䉒䈞䈩␜䈜䇯䈘䉌䈮䇮䈠䈱ᐔဋ H/V 䉴䊕䉪䊃䊦䉋䉍⺒䉂㪈㪏㩷䈇䈩䈲䇮੹ᓟㆡಾ䈭䉝䊧䊷䉰䉟䉵䈮䉋䉎᷹ቯ䉕ታᣉ䈚䇮ᬌ⸽䈫⹏ଔ䉕ⴕ䈉੍ቯ䈪䈅䉎䇯䈖䈉䈋䈇䊐䉤䊷䊤䊛╙ 㪈㪈 ภ㩷 㪆㩷㪉㪇㪇㪊㪅㪈㩷࿑䋭㪏㪸㩷 㩷 ฦ࿾ὐ䈮䈍䈔䉎㪟㪆㪭䉴䊕䉪䊃䊦㩷࿑䋭㪏㪹㩷 㩷 ฦ࿾ὐ䈮䈍䈔䉎 㪟㪆㪭 䉴䊕䉪䊃䊦㩷㪈㪐㩷常時微動に基づく岩手県・雫石盆地の地盤構造推定ෳ⠨ᢥ₂1)ਛ᧛ ᤯䇮㘑㑆ၮ᮸䇮ዊᨋᤩ䇮ᄢⷺᕡ㓶(1999)䇮:ጤᚻ⋵ർㇱ࿾㔡
(1998.9.3)䈮䉋䉎ⵍኂ䈫࿾㔡േ․ᕈ䇮No.35䇮᧲ർ࿾ၞἴኂ⑼ቇ⎇ⓥ䇮pp.87-922)

࿯ ᧁ ቇ ળ ✬ (1999) 䇮 THE 1999 JI-JI EARTHQUAKE,TAIWAN -Investigation into Damage to Civil Engineering
Structures-.

3)ਛ᧛ ᤯:䊔䉪䊃䊦䉴䊕䉪䊃䊦䈮䉋䉎࿾㔡േ䈱Ⴧ᏷․ᕈ⹏ଔ䇮࿯ᧁቇળ⺰ᢥ㓸䇮No.519䇮pp161-173䇮1995.3

4)

Aki,K,S(1957),SpaceandTime

Spectraof Stationary

Stochastic Waves, with Specific Reference to Microtremors,
Bull. Earth. Res. Inst.,35,415-456.
5)᧻ጟ ㆐㇢䇮᪢ᴛ ᄐ⟤䇮Ꮞፉ ⑲ᄦ䇮࿾ਅ᭴ㅧផቯ䈱䈢䉄䈱ⓨ㑆⥄Ꮖ⋧㑐ᴺ䈱ㆡ↪ᕈ䈮㑐䈜䉎ᬌ⸛䇮‛ℂតᩏ䇮╙ 49 Ꮞ䇮╙䋱ภpp26-41䇮19966)

Morikawa,H,S.Sawada,K.,Toki,J.,

Akamatsu,D.,

Nakajima,J., Ejiri and K., Miyakoshi(1999), Estimation of
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from Microtremors observed at two sites,

Proc. 2nd Int. Conf. Earthquake Geotechnical Enginering,
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7)

ᚭ⿧ㅺੱ䇮ችဈ⧷ᔒ䇮Ḯᩕᱜੱ䇮ᩊ↰᣿ᓼ(1999)䇮䉝䊧䊷ᓸേ᷹ⷰ䈮ၮ䈨䈒઄บ࿾ၞ䈱ᷓㇱ࿾ਅ᭴ㅧ䈱ផቯ-2 ὐ SPAC ᴺ䈮ၮ䈨䈒㐳↸࿾඙䈱᭴ㅧ-䇮᧲ർ࿾ၞἴኂ⑼ቇ⎇ⓥ䇮35䇮39-428)Ꮏᬺᛛⴚ㒮࿾⾰⺞ᩏᚲ⋙ୃ(1996)䇮ℂ⑼ᐕ⴫⺒ᧄ䇮䉮䊮䊏䊠䊷䉺䊷䉫䊤䊐䉞䉾䉪ᣣᧄ೉ፉ䈱࿾⾰䇮ਣༀ(ᩣ)

20