６－５

東海・南関東地域における歪観測結果（2008年5月～10月）
Observation of Crustal Strain by Borehole Strainmeters in the Tokai andSouthern Kanto Districts (May – October 2008)
気象庁 地震予知情報課
Earthquake Prediction Information Division, JMA

第1図は，気象庁が東海・南関東地域において観測している埋込式体積歪計 1)と多成分歪計 2)の配置と区域分けである．第2図に2001年以来の体積歪変化を，第3図に2007年5月から2008年10月までの体積歪変化を示す．第4図は多成分歪計の経年変化である．第5図に2007年5月から2008年10月までの多成分歪計の変化を示す．主歪の方向と大きさ，最大せん断歪及び面積歪は，潮汐応答及び長周期地震波形に基づいて較正されている 3)．
東海地域では，2008年5月15日頃から5月19日頃にかけて，愛知県で発生したと考えられる短期的スロースリップ（短期的ゆっくり滑り）に伴う変化が，蒲郡，掛川，春野，佐久間，本川根及び浜北で観測された（第5図(a), (b), (c), (d)の*1）（本巻※1参照）．
東海地域では，2008年8月25日頃から9月5日頃にかけて，長野県南部から愛知県で発生したと考えられる短期的スロースリップに伴う変化が，掛川，春野，佐久間，本川根及び浜北で観測された（第5図(a), (b), (c), (d)の*2）（本巻※1参照）．
また，東伊豆と大島では，地中温度の上昇を主因とする見かけ上の縮みトレンドが続いている（第2図(b), (c)）4)5)．この他の変化として，各図に記述したように降水による影響と見られるもの，季節要因によるもの，何らかの人為的要因による変化などが見られた．
※1：「東海地域の低周波地震活動と短期的スロースリップ（2008年5月～10月）」（気象庁）
参考文献1) 二瓶信一・上垣内修・佐藤 馨：埋込式体積歪計による観測，1976年～1986年の観測経過，験震
時報，50, 65-88 (1987).
2) 石井紘ほか：新しい小型多成分ボアホール歪計の開発と観測，地球惑星科学関連学会1992年合同大会予稿集，C22-03 (1992).
3) 上垣内修ほか：気象庁石井式歪計の応答特性解析，1999年度日本地震学会秋季大会予稿集，B72(1999).
4) 気象庁：東海・南関東地域における歪観測結果（2006年5月～2006年10月），連絡会報，77 (2006)5) 気象庁：東海・南関東地域における歪観測結果（2006年11月～2007年4月），連絡会報，78 (2007).

㪄㩷㪋㪌㪋㩷㪄

╙1࿑ ၒㄟᑼᱡ⸘ߩ㈩⟎࿑Fig. 1㧦૕Ⓧᱡ⸘㧘㧦ᄙᚑಽᱡ⸘㧔᳇⽎ᐡ㧕㧘ٌ㧦ห㧔㕒ጟ⋵㧕

Network for the observation of crustal strain by borehole strainmeters㪄㩷㪋㪌㪌㩷㪄╙2࿑(c) 2001ᐕ1᦬એᓟߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔ᣣᐔဋ୯㧕㧚ฦ࿑ਅㇱ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚
Fig. 2(c) Changes in crustal volume strain for regions 1 – 6 shown in Fig.1
since January 2001 (daily mean values)╙2࿑(a) 2001ᐕ1᦬એᓟߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔ᣣᐔဋ୯㧕㧚ฦ࿑ਅㇱ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚
Fig. 2(a) Changes in crustal volume strain for regions 1 – 6 shown in Fig.1
since January 2001 (daily mean values)╙2࿑(d) 2001ᐕ1᦬એᓟߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔ᣣᐔဋ୯㧕㧚ฦ࿑ਅㇱ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚
Fig. 2(d) Changes in crustal volume strain for regions 1 – 6 shown in Fig.1
since January 2001 (daily mean values)╙2࿑(b) 2001ᐕ1᦬એᓟߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔ᣣᐔဋ୯㧕㧚ฦ࿑ਅㇱ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚
Fig. 2(b) Changes in crustal volume strain for regions 1 – 6 shown in Fig.1
since January 2001 (daily mean values)㪄㩷㪋㪌㪍㩷㪄╙3࿑(a)Fig. 3(a)╙3࿑(b)

2007ᐕ5᦬㨪2008ᐕ10᦬ߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔Ფᤨ୯㧦᳇࿶࡮ầ᳤࡮㒠᳓⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚࿾ὐฬߩਅߩD/day෸߮ /Mߪߘࠇߙࠇ1ᣣ޽ߚࠅߩ࠻࡟ࡦ࠼ᄌൻ㊂ࠍ
Dߣߒߡ⵬ᱜߒߡ޿ࠆߎߣ෸߮1/M୚ߦߒߡ⴫␜ߒߡ޿ࠆߎߣࠍ␜ߒߡ޿ࠆ㧚(a) ⫱㇭ߢ2008ᐕ5᦬15ᣣ㗃߆ࠄ19ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Changes in crustal volume strain for regions 1 – 6 shown in Fig.1 from May
2007 – October 2008 (hourly values where changes due to barometric pressure,tidal effects and rain effects are corrected).
D/day and /M shown below station names mean that the linear trend D(/day)is subtracted and that data are shown after being multiplied by 1/M.
(a) At Gamagori, rapid expansion was observed on May 15 to 19, 2008; which
was associated with short-term slow slip event (*1).

Fig. 3(b)㪄㩷㪋㪌㪎㩷㪄

2007ᐕ5᦬㨪2008ᐕ10᦬ߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔Ფᤨ୯㧦᳇࿶࡮ầ᳤࡮㒠᳓⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚࿾ὐฬߩਅߩD/day෸߮ /Mߪߘࠇߙࠇ1ᣣ޽ߚࠅߩ࠻࡟ࡦ࠼ᄌൻ㊂ࠍ
Dߣߒߡ⵬ᱜߒߡ޿ࠆߎߣ෸߮1/M୚ߦߒߡ⴫␜ߒߡ޿ࠆߎߣࠍ␜ߒߡ޿ࠆ㧚(b) ⫱㇭ߢ2008ᐕ5᦬15ᣣ㗃߆ࠄ19ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ
㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Changes in crustal volume strain for regions 1 – 6 shown in Fig.1 from May
2007 – October 2008 (hourly values where changes due to barometric pressure,tidal effects and rain effects are corrected).
D/day and /M shown below station names mean that the linear trend D(/day)is subtracted and that data are shown after being multiplied by 1/M.
(b) At Gamagori, rapid expansion was observed on May 15 to 19, 2008; which
was associated with short-term slow slip event (*1).

╙3࿑(d)2007ᐕ5᦬㨪2008ᐕ10᦬ߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔Ფᤨ୯㧦᳇࿶࡮ầ᳤࡮㒠᳓⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚࿾ὐฬߩਅߩD/day෸߮ /Mߪߘࠇߙࠇ1ᣣ޽ߚࠅߩ࠻࡟ࡦ࠼ᄌൻ㊂ࠍDߣߒߡ⵬ᱜߒߡ
޿ࠆߎߣ෸߮1/M୚ߦߒߡ⴫␜ߒߡ޿ࠆߎߣࠍ␜ߒߡ޿ࠆ㧚(a)⫱㇭ߢ2008ᐕ5᦬15ᣣ㗃߆ࠄ19ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Fig. 3(d) Changes in crustal volume strain for regions 1 – 6 shown in Fig.1 from May 2007 – October
2008 (hourly values where changes due to barometric pressure, tidal effects and rain effects
are corrected). D/day and /M shown below station names mean that the linear trend D(/day) issubtracted and that data are shown after being multiplied by 1/M.
(a) At Gamagori, rapid expansion was observed on May 15 to 19, 2008; which was associatedwith short-term slow slip event (*1).

╙3࿑(c)

Fig. 3(c)2007ᐕ5᦬㨪2008ᐕ10᦬ߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔Ფᤨ୯㧦᳇࿶࡮ầ᳤࡮㒠᳓⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚࿾ὐฬߩਅߩD/day෸߮ /Mߪߘࠇߙࠇ1ᣣ޽ߚࠅߩ࠻࡟ࡦ࠼ᄌൻ㊂ࠍDߣߒߡ⵬ᱜߒߡ޿ࠆߎߣ෸߮1/M୚ߦߒߡ⴫␜ߒߡ޿ࠆߎߣࠍ␜ߒߡ޿ࠆ㧚(c) ⫱㇭ߢ2008ᐕ5᦬15ᣣ㗃߆ࠄ19ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Changes in crustal volume strain for regions 1 – 6 shown in Fig.1 from May
2007 – October 2008 (hourly values where changes due to barometric pressure,tidal effects and rain effects are corrected).
D/day and /M shown below station names mean that the linear trend D(/day)is subtracted and that data are shown after being multiplied by 1/M.
(c) At Gamagori, rapid expansion was observed on May 15 to 19, 2008; which
was associated with short-term slow slip event (*1).

╙3࿑(e)

Fig. 3(e)㪄㩷㪋㪌㪏㩷㪄

2007ᐕ5᦬㨪2008ᐕ10᦬ߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔Ფᤨ୯㧦᳇࿶࡮ầ᳤࡮㒠᳓⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚࿾ὐฬߩਅߩD/day෸߮ /Mߪߘࠇߙࠇ1ᣣ޽ߚࠅߩ࠻࡟ࡦ࠼ᄌൻ㊂ࠍDߣߒߡ⵬ᱜߒߡ޿ࠆߎߣ෸߮1/M୚ߦߒߡ⴫␜ߒߡ޿ࠆߎߣࠍ␜ߒߡ޿ࠆ㧚(e) ⫱㇭ߢ2008ᐕ5᦬15ᣣ㗃߆ࠄ19ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ
㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Changes in crustal volume strain for regions 1 – 6 shown in Fig.1 from May
2007 – October 2008 (hourly values where changes due to barometric pressure,tidal effects and rain effects are corrected).
D/day and /M shown below station names mean that the linear trend D(/day)is subtracted and that data are shown after being multiplied by 1/M.
(e) At Gamagori, rapid expansion was observed on May 15 to 19, 2008; which
was associated with short-term slow slip event (*1).

╙3࿑(f)Fig. 3(f)2007ᐕ5᦬㨪2008ᐕ10᦬ߩ᧲ᶏ࡮ධ㑐᧲࿾ၞߦ߅ߌࠆ඙ၞ೎૕Ⓧᱡᄌൻ㧔Ფᤨ୯㧦᳇࿶࡮ầ᳤࡮㒠᳓⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ඙ၞࠍઍ⴫ߔࠆ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚࿾ὐฬߩਅߩD/day෸߮ /Mߪߘࠇߙࠇ1ᣣ޽ߚࠅߩ࠻࡟ࡦ࠼ᄌൻ㊂ࠍ
Dߣߒߡ⵬ᱜߒߡ޿ࠆߎߣ෸߮1/M୚ߦߒߡ⴫␜ߒߡ޿ࠆߎߣࠍ␜ߒߡ޿ࠆ㧚(f) ⫱㇭ߢ2008ᐕ5᦬15ᣣ㗃߆ࠄ19ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Changes in crustal volume strain for regions 1 – 6 shown in Fig.1 from May
2007 – October 2008 (hourly values where changes due to barometric pressure,tidal effects and rain effects are corrected).
D/day and /M shown below station names mean that the linear trend D(/day)is subtracted and that data are shown after being multiplied by 1/M.
(f) At Gamagori, rapid expansion was observed on May 15 to 19, 2008; which
was associated with short-term slow slip event (*1).

╙4࿑(a) ᄙᚑಽᱡ⸘ᄌൻ㧔ᣣᐔဋ୯㧕㧚ਥᱡ࡮ᦨᄢߖࠎᢿᱡ࡮㕙Ⓧᱡߪ
ฦᣇะᚑಽ߆ࠄ⸘▚ߐࠇߡ޿ࠆ㧚
Fig. 4(a)Strain changes (daily mean values) observed by multi-component
borehole strainmeters. Principal strain, maximum shear strain
and dilatation are calculated with strain values obtained from eachcomponent.

㪄㩷㪋㪌㪐㩷㪄

╙4࿑(c) ᄙᚑಽᱡ⸘ᄌൻ㧔ᣣᐔဋ୯㧕㧚ਥᱡ࡮ᦨᄢߖࠎᢿᱡ࡮㕙Ⓧᱡߪฦᣇะᚑಽ߆ࠄ⸘▚ߐࠇߡ޿ࠆ㧚
Fig. 4(c)Strain changes (daily mean values) observed by multi-component
borehole strainmeters. Principal strain, maximum shear strain
and dilatation are calculated with strain values obtained from eachcomponent.

╙4࿑(b) ᄙᚑಽᱡ⸘ᄌൻ㧔ᣣᐔဋ୯㧕㧚ਥᱡ࡮ᦨᄢߖࠎᢿᱡ࡮㕙Ⓧᱡߪ
ฦᣇะᚑಽ߆ࠄ⸘▚ߐࠇߡ޿ࠆ㧚
Fig. 4(b)Strain changes (daily mean values) observed by multi-component
borehole strainmeters. Principal strain, maximum shear strain
and dilatation are calculated with strain values obtained from eachcomponent.

㪄㩷㪋㪍㪇㩷㪄

╙4࿑(e) ᄙᚑಽᱡ⸘ᄌൻ㧔ᣣᐔဋ୯㧕㧚ਥᱡ࡮ᦨᄢߖࠎᢿᱡ࡮㕙Ⓧᱡߪ
ฦᣇะᚑಽ߆ࠄ⸘▚ߐࠇߡ޿ࠆ㧚
Fig. 4(e)Strain changes (daily mean values) observed by multi-component
borehole strainmeters. Principal strain, maximum shear strain
and dilatation are calculated with strain values obtained from eachcomponent.

╙4࿑(d) ᄙᚑಽᱡ⸘ᄌൻ㧔ᣣᐔဋ୯㧕㧚ਥᱡ࡮ᦨᄢߖࠎᢿᱡ࡮㕙Ⓧᱡߪฦᣇะᚑಽ߆ࠄ⸘▚ߐࠇߡ޿ࠆ㧚
Fig. 4(d)Strain changes (daily mean values) observed by multi-component
borehole strainmeters. Principal strain, maximum shear strain
and dilatation are calculated with strain values obtained from eachcomponent.

㪄㩷㪋㪍㪈㩷㪄

╙ 5 ࿑(b) 2007 ᐕ 5 ᦬㨪2008 ᐕ 10 ᦬ߩᄙᚑಽᱡ⸘ᄌൻ
㧔ᤨ㑆୯㧦᳇࿶࡮ầ᳤⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚
ᤐ㊁෸߮૒ਭ㑆ߦ߅޿ߡ 2008 ᐕ 5 ᦬ 15 ᣣ㗃߆ࠄ 19 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚ដᎹ㧘ᤐ㊁㧘૒ਭ㑆㧘ᧄᎹᩮ෸߮ᵿർߦ߅޿ߡ 2008 ᐕ 8 ᦬ 25 ᣣ㗃߆ࠄ9 ᦬ 5 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Fig. 5(b)  Strain changes from May 2007 – October 2008 (hourly values correctedwith barometric pressure and tidal data) observed by multi-component
borehole strainmeters.
Rapid expansion and/or contraction was observed on May 15 to 19, 2008in (b) the 1st and 2nd component at Haruno and (c) all component
which was associated with short-term slow slip event (*1). at Sakuma;
Rapid expansion and/or contraction was observed on August 25 to September
5, 2008 in (a) all component at Kakegawa, (b) all component at Haruno,(c) the 2nd and 4th component at Sakuma, (d) the 2nd, 3rd and 4th componentat Honkawane, and (e) the 1st component at Hamakita, which was associatedwith short-term slow slip event (*2).

╙ 5 ࿑(a) 2007 ᐕ 5 ᦬㨪2008 ᐕ 10 ᦬ߩᄙᚑಽᱡ⸘ᄌൻ
㧔ᤨ㑆୯㧦᳇࿶࡮ầ᳤⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚
ᤐ㊁෸߮૒ਭ㑆ߦ߅޿ߡ 2008 ᐕ 5 ᦬ 15 ᣣ㗃߆ࠄ 19 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚ដᎹ㧘ᤐ㊁㧘૒ਭ㑆㧘ᧄᎹᩮ෸߮ᵿർߦ߅޿ߡ 2008 ᐕ 8 ᦬ 25 ᣣ㗃߆ࠄ9 ᦬ 5 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Fig. 5(a)  Strain changes from May 2007 – October 2008 (hourly values correctedwith barometric pressure and tidal data) observed by multi-component
borehole strainmeters.
Rapid expansion and/or contraction was observed on May 15 to 19, 2008in (b) the 1st and 2nd component at Haruno and (c) all component
which was associated with short-term slow slip event (*1). at Sakuma;
Rapid expansion and/or contraction was observed on August 25 to September
5, 2008 in (a) all component at Kakegawa, (b) all component at Haruno,(c) the 2nd and 4th component at Sakuma, (d) the 2nd, 3rd and 4th componentat Honkawane, and (e) the 1st component at Hamakita, which was associatedwith short-term slow slip event (*2).

㪄㩷㪋㪍㪉㩷㪄╙ 5 ࿑(d) 2007 ᐕ 5 ᦬㨪2008 ᐕ 10 ᦬ߩᄙᚑಽᱡ⸘ᄌൻ
㧔ᤨ㑆୯㧦᳇࿶࡮ầ᳤⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚
ᤐ㊁෸߮૒ਭ㑆ߦ߅޿ߡ 2008 ᐕ 5 ᦬ 15 ᣣ㗃߆ࠄ 19 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚ដᎹ㧘ᤐ㊁㧘૒ਭ㑆㧘ᧄᎹᩮ෸߮ᵿർߦ߅޿ߡ 2008 ᐕ 8 ᦬ 25 ᣣ㗃߆ࠄ9 ᦬ 5 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Fig. 5(d)  Strain changes from May 2007 – October 2008 (hourly values correctedwith barometric pressure and tidal data) observed by multi-component
borehole strainmeters.
Rapid expansion and/or contraction was observed on May 15 to 19, 2008in (b) the 1st and 2nd component at Haruno and (c) all component
which was associated with short-term slow slip event (*1). at Sakuma;
Rapid expansion and/or contraction was observed on August 25 to September
5, 2008 in (a) all component at Kakegawa, (b) all component at Haruno,(c) the 2nd and 4th component at Sakuma, (d) the 2nd, 3rd and 4th componentat Honkawane, and (e) the 1st component at Hamakita, which was associatedwith short-term slow slip event (*2).

╙ 5 ࿑(c) 2007 ᐕ 5 ᦬㨪2008 ᐕ 10 ᦬ߩᄙᚑಽᱡ⸘ᄌൻ㧔ᤨ㑆୯㧦᳇࿶࡮ầ᳤⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚ᤐ㊁෸߮૒ਭ㑆ߦ߅޿ߡ 2008 ᐕ 5 ᦬ 15 ᣣ㗃߆ࠄ 19 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚ដᎹ㧘ᤐ㊁㧘૒ਭ㑆㧘ᧄᎹᩮ෸߮ᵿർߦ߅޿ߡ 2008 ᐕ 8 ᦬ 25 ᣣ㗃߆ࠄ9 ᦬ 5 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Fig. 5(c)  Strain changes from May 2007 – October 2008 (hourly values correctedwith barometric pressure and tidal data) observed by multi-component
borehole strainmeters.
Rapid expansion and/or contraction was observed on May 15 to 19, 2008in (b) the 1st and 2nd component at Haruno and (c) all component
which was associated with short-term slow slip event (*1). at Sakuma;
Rapid expansion and/or contraction was observed on August 25 to September
5, 2008 in (a) all component at Kakegawa, (b) all component at Haruno,(c) the 2nd and 4th component at Sakuma, (d) the 2nd, 3rd and 4th componentat Honkawane, and (e) the 1st component at Hamakita, which was associatedwith short-term slow slip event (*2).

㪄㩷㪋㪍㪊㩷㪄╙ 5 ࿑(e) 2007 ᐕ 5 ᦬㨪2008 ᐕ 10 ᦬ߩᄙᚑಽᱡ⸘ᄌൻ
㧔ᤨ㑆୯㧦᳇࿶࡮ầ᳤⵬ᱜߒߚ୯㧕㧚ฦ࿑ਅㇱߦ᳇࿶ᄌൻߣ㒠᳓㊂ࠍ␜ߔ㧚
ᤐ㊁෸߮૒ਭ㑆ߦ߅޿ߡ 2008 ᐕ 5 ᦬ 15 ᣣ㗃߆ࠄ 19 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊ㧔⍴ᦼ⊛ࠁߞߊࠅṖࠅ㧕ߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚ដᎹ㧘ᤐ㊁㧘૒ਭ㑆㧘ᧄᎹᩮ෸߮ᵿർߦ߅޿ߡ 2008 ᐕ 8 ᦬ 25 ᣣ㗃߆ࠄ9 ᦬ 5 ᣣ㗃ߦ߆ߌߡ⍴ᦼ⊛ࠬࡠ࡯ࠬ࡝࠶ࡊߦ઻߁ᱡᄌൻ߇᷹ⷰߐࠇߚ㧚
Fig. 5(e)  Strain changes from May 2007 – October 2008 (hourly values correctedwith barometric pressure and tidal data) observed by multi-component
borehole strainmeters.
Rapid expansion and/or contraction was observed on May 15 to 19, 2008in (b) the 1st and 2nd component at Haruno and (c) all component
which was associated with short-term slow slip event (*1). at Sakuma;
Rapid expansion and/or contraction was observed on August 25 to September
5, 2008 in (a) all component at Kakegawa, (b) all component at Haruno,(c) the 2nd and 4th component at Sakuma, (d) the 2nd, 3rd and 4th componentat Honkawane, and (e) the 1st component at Hamakita, which was associatedwith short-term slow slip event (*2).

㪄㩷㪋㪍㪋㩷㪄