ⅆᒣᄇⅆண▱㐃⤡఍఍ሗ ➨ ྕ ᐩኈᒣࡢᆅ㟈άື࣭ᆅẆኚື㸨㻌 Seismic activity and crustal deformation at Fuji volcano 㜵⅏⛉Ꮫᢏ⾡◊✲ᡤ** National Research Institute for Earth Science and Disaster Prevention ᖺ㸶᭶ ᪥࠿ࡽ ᖺ㸰᭶ ᪥ࡲ࡛ࡢᮇ㛫࡟࠾ࡅࡿᆅ㟈άື࡜ᆅẆኚື࡟ࡘ࠸࡚ሗ࿌ࡍࡿࠋ ➨㸯ᅗࡣ㜵⅏⛉◊ⅆᒣほ ⥙ࡢᐃᖖฎ⌮࡛࠾ࡇ࡞ࡗ࡚࠸ࡿ㟈ኸศᕸᅗ࡛࠶ࡿࠋᫍ༳ࡣ ᖺ㸱᭶ ᪥࡟Ⓨ⏕ࡋࡓ㟼ᒸ┴ᮾ㒊ᆅ㟈ࡢᮏ㟈0Mࡢ఩⨨ࢆ♧ࡍࠋవ㟈άືࡣῶᑡࡋ࡞ࡀࡽࡶࠊ⥅⥆ࡋ࡚࠸ࡿࠋ 㟈※ᇦࡢᘏ㛗㒊࡟࠶ࡓࡿᐩኈᒣࡢᒣ㯄໭ഃ㸦➨㸯ᅗձᇦ㸧ࡢάືࡣࠊ ᖺ㸱㹼㸴᭶㡭ࡲ࡛Ⓨ⏕ࡋ࡚࠸ ࡓࡀࠊࡑࡢᚋⓎ⏕ᩘࡣῶࡗࡓࠋࡲࡓࠊᐩኈᒣ໭す㯄㸱ྜ┠௜㏆࡛‫‮‬Ẽࡀ☜ㄆࡉࢀࡓ௜㏆➨㸯ᅗղᇦ࡛ ࡣࠊ῝ࡉ㸳NP ࡼࡾὸ࠸ᆅ㟈άືࡣ࡯࡜ࢇ࡝㉳ࡇࡗ࡚࠸࡞࠸ࠋ ➨㸰ᅗࡣప࿘Ἴᆅ㟈άືࡢ᫬㛫ኚ໬ࢆ♧ࡍ⳻ᙧࢲ࢖࢔ࢢ࣒࡛ࣛ࠶ࡿࠋ➨㸱ᅗࡣ ᖺ௨㝆ࡢ✚⟬ప ࿘Ἴᆅ㟈άືᅇᩘ࡜✚⟬ᴫ⟬άື࢚ࢿࣝࢠ࣮ࡢ᫬㛫ኚ໬ࢆ♧ࡋࡓࠋ➨㸰ᅗ࡜➨㸱ᅗ࡟♧ࡋࡓࡼ࠺࡟ࠊప ࿘Ἴᆅ㟈άືࡣ㟼ᒸ┴ᮾ㒊ᆅ㟈ࡢⓎ⏕࡟㛵㐃ࡍࡿࡼ࠺࡞㢧ⴭ࡞ኚ໬ࡣㄆࡵࡽࢀ࡞࠸ࠋ ➨㸲ᅗࡣ㜵⅏⛉◊ࡢᐩኈⅆᒣάືほ ⥙࡟タ⨨ࡋࡓ ࢝ᡤࡢ࣎࢔࣮࣍ࣝᘧഴᩳィࢹ࣮ࢱṇ᫬್࡛࠶ ࡿࠋ ᖺ㸶᭶㸯᪥㥴Ἑ‴Ἀࡢᆅ㟈0Mࡸ ᖺ㸯᭶ ᪥ᒣ᲍┴ᮾ㒊䞉ᐩኈ஬†ࡢᆅ㟈0M࡟ క࠺ࢫࢸࢵࣉࡀほ ࡉࢀࡓࠋ࡞࠾ࠊ)-6 ࡸ )-ࠊ)- ほ Ⅼ࡛ࡣࠊ㸵᭶௨㝆グ㘓ࡀ኱ࡁࡃᦂࡽ࠸࡛࠸ࡿࠋ ࡇࢀࡣྎ㢼➼ࡢ㝆㞵࡟ࡼࡿᙳ㡪࡛࠶ࡾࠊⅆᒣάື࡟㛵㐃ࡋࡓ␗ᖖ࡜ࡣ⪃࠼ࡽࢀ࡞࠸ࠋࡲࡓࠊ)- ࡟ࡣ ᭶ ᪥㟼ᒸ┴ᮾ㒊ᆅ㟈࡟ࡼࡗ࡚⿕ᐖࢆཷࡅࡓ㐨㊰ᕤ஦ࡢᙳ㡪࡜⪃࠼ࡽࢀࡿኚືࣀ࢖ࢬࡀグ㘓ࡉࢀࡓࠋ ➨㸳ᅗࡣᐩኈⅆᒣάືほ ⥙ࡢ㸱ほ Ⅼ࡜㧗ឤᗘᆅ㟈ほ ⥙ +LQHW ࡢᐩኈᐑほ Ⅼ )-0 ࡟タ⨨ࡋࡓ *36 㛫ࡢᇶ⥺㛗ኚ໬᪥ᖹᆒ್࡛࠶ࡿࠋ኱Ẽ୰ࡢỈ⵨Ẽ㔞ࡢኚ໬࡟㉳ᅉࡍࡿ࡜⪃࠼ࡽࢀࡿᖺ࿘ኚ໬ࡸ㟼 ᒸ┴ᮾ㒊ᆅ㟈࡟క࠺ࢫࢸࢵࣉࡀほ ࡉࢀࡓࡶࡢࡢࠊⅆᒣάື࡟㛵㐃ࡍࡿࡼ࠺࡞ኚືࡣㄆࡵࡽࢀ࡞࠿ࡗࡓࠋ ࡞࠾ࠊ㸷᭶୰᪪࡟ぢࡽࢀࡿࢫࢸࢵࣉࡣᐩኈᐑほ Ⅼ )-0 ࡢᒁᡤⓗ࡞ኚື࡟㉳ᅉࡋ࡚Ⓨ⏕ࡋ࡚࠸ࡿࡀࠊࡑ ࡢཎᅉࡣ୙࡛᫂࠶ࡿࠋ * ᖺ䠐᭶䠎᪥ཷ௜ ** Ჴ⏣ಇᨲ䠈Ἑ㔝⿱ᕼ䠈⸨⏣ⱥ㍜䠈ୖ⏣ⱥᶞ䠈ᑠᅬㄔྐ䠈㛗஭㞞ྐ䠈㬼ᕝඖ㞝 Toshikazu Tanada, Yuhki Kohno, Eisuke Fujita, Hideki Ueda, Tomofumi Kozono, Masashi Nagai, Motoo Ukawa ⅆᒣᄇⅆண▱㐃⤡఍఍ሗ ➨ ྕ ᐩኈᒣ䛾ᆅ㟈άື(2011/8䡚2012/2/10) ➨㸯ᅗ ᐩኈᒣࡢ㟈※ศᕸ࠾ࡼࡧ 07 ᅗࠋప࿘Ἴᆅ㟈ࡣ㉥୸㸦‫ە‬㸧࡛♧ࡋࡓࠋࡇࡢᆅᅗࡣࠊᅜᅵᆅ⌮㝔Ⓨ⾜ ࡢᩘ್ᆅᅗ P ࣓ࢵࢩࣗ㸦ᶆ㧗㸧ࢆ౑⏝ࡋࡓࡶࡢ࡛࠶ࡿࠋ Fig.1 Hypocenter distribution around Fuji Volcano and M-T diagram. Red solid circles show locations of the low frequency earthquakes. ⅆᒣᄇⅆண▱㐃⤡఍఍ሗ ➨ ྕ ➨㸰ᅗ ᐩኈᒣࡢప࿘Ἴᆅ㟈άືࡢ᫬㛫ኚ໬ࢆ♧ࡍ⳻ᙧࢲ࢖࢔ࢢ࣒ࣛ ᖺ࠿ࡽ ᖺ㸰᭶ ᪥ࠋ⳻ᙧ ࡢ㧗ࡉࡣ≉ᐃࡢほ Ⅼ࡛グ㘓ࡉࢀࡓప࿘Ἴᆅ㟈άືࡢ᣺ື⥅⥆᫬㛫ࠊᖜࡣࡑࡢ᭱኱᣺ᖜࢆ♧ࡍࠋ Fig.2 Diamond diagram showing seismic activity of the low frequency earthquakes at Fuji volcano(January 1,㻌 1997 to February 10, 2012). The hight and width of diamond correspond to the duration and maximum amplitude of each low frequency earthquake recorded at the specific stations. ➨㸱ᅗ ✚⟬ప࿘Ἴᆅ㟈άືᅇᩘ⅊Ⰽ⥺࡜✚⟬ᴫ⟬άື࢚ࢿࣝࢠ࣮ᅗ㯮⥺ ᖺ㹼 ᖺ㸰᭶ ᪥ ✚⟬Ἴື࢚ࢿࣝࢠ࣮( ࡣࠊ( $PD[7'7ࠊ$PD[ ࡜ 7' ࡣ≉ᐃほ Ⅼ࡛ࡢ᭱኱᣺ᖜ࡜᣺ື⥅⥆᫬㛫ࠊ7 ࡣ༟㉺࿘ᮇ࡛ࡇࡇ࡛ࡣ୍ᐃ࡜ࡋ࡚ᢅࡗ࡚࠸ࡿࠋ Fig.3 Cumulative number of the low frequency earthquake activity(gray curve) and cumulative seismic wave energy(black curve) calculated from the observed maximum amplitude and duration at the specific stations(January 1,㻌 1997 to February 10,㻌 2012). ⅆᒣᄇⅆண▱㐃⤡఍఍ሗ ➨ ྕ ➨㸲ᅗ 㜵⅏⛉Ꮫᢏ⾡◊✲ᡤ࣭ᐩኈᒣⅆᒣάືほ ⥙࡟ࡼࡿഴᩳኚືほ ⤖ᯝࠋ⾲♧ᮇ㛫ࡣ ᖺ㸴᭶㸯᪥ 㹼 ᖺ㸰᭶ ᪥࡛ࠊ⾲♧ࢹ࣮ࢱࡣ᫬್㸦ẖṇ᫬ࡢ್㸧ࠋ Fig. 4 Tilt changes observed by NIED Fuji volcano observation network for the period from June 1, 2011 to February 10, 2012. Hourly data are plotted. ⅆᒣᄇⅆண▱㐃⤡఍఍ሗ ➨ ྕ ➨㸳ᅗ 㜵⅏⛉Ꮫᢏ⾡◊✲ᡤ࣭ᐩኈᒣⅆᒣάືほ ⥙࡟ࡼࡿ *36 ほ ⤖ᯝࠋ⾲♧ᮇ㛫ࡣ ᖺ ᭶ ᪥㹼 ᖺ㸰᭶ ᪥࡛ࠊ⾲♧ࢹ࣮ࢱࡣᇶ⥺㛗ኚ໬ࡢ᪥ᖹᆒ್ࠋ Fig. 5 Baseline length changes between GPS stations of the NIED Fuji volcano observation network for the period from October 24, 2002 to February 10, 2011. Daily mean data are plotted.