2D
◁♟ሁ✚㠃࡟࠾ࡅࡿ⾲㠃ὶฟ࡜◁♟ࡢὶື໬㟼ᒸ኱Ꮫ㎰Ꮫ㒊 ࠐ௒Ἠᩥᑑ࣭ᅵᒇ ᬛ࣭㐂ᆏ⯆ᏹ㟼ᒸ኱Ꮫ኱Ꮫ㝔㎰Ꮫ◊✲⛉㸦⌧ ᪥ᮏᕤႠ㸦ᰴ㸧㸧ఀ⸨ ᗈ

rainfall intensity
timing of mobilization (mm/5min)㪄㩷㪙㪄㪉㪏㪇㩷㪄cumulative rainfall (mm)rainfall intensity (mm/10min)䠍䠊䛿䛨䜑䛻㻌
video camera ᅵ▼ὶࡢほ ࡣ୺࡟ὶ㏦ᇦ࡟࠾࠸࡚⾜ࢃࢀ
captured area࡚࠾ࡾ㸪ᅵ▼ὶࡢⓎ⏕ᇦ࡟࠾ࡅࡿほ ஦౛ࡣஈchannel deposits
talus slopes
ࡋ࠸ࠋ㏆ᖺࡣ⚄㏻ᕝỈ⣔ࣄࣝ㇂㸦Ỉ㇂ࡽ㸪2008㸧
debris flow startࡸ⸨ཎᓅすஅ㈅ᡞᕝ㸦ᒣ⏣ࡽ㸪2009㸧➼࡟࠾
points࠸࡚⢭ຊⓗ࡞ほ ࡀ⾜ࢃࢀ࡚࠾ࡾ㸪ᅵ▼ὶࡢⓎ
P2
⏕࡟㛵ࢃࡿỈᩥ≉ᛶࡢᢕᥱࡀヨࡳࡽࢀ࡚࠸ࡿP1ࡀ㸪ᅵ◁ࡢὶື໬࡟㛵ࡍࡿ▱ぢࡣᮍࡔ༑ศ࡟ᚓV1ࡽࢀ࡚࠸ࡿ࡜ࡣ࠸࠼࡞࠸ࠋࡑࡇ࡛ᮏ◊✲࡛ࡣ㸪㟼ᒸ┴໭㒊኱㇂ᔂෆࡢᅵ▼ὶⓎ⏕ᇦ࡟࠾࠸࡚
ࣅࢹ࣓࢜࢝ࣛ࡟ࡼࡿᅵ▼ὶほ ࢆ⾜࠸㸪ᅵ◁ࡀ
V2ὶື໬ࡍࡿ㐣⛬ࡢ⌧㇟ㄽⓗᢕᥱࢆヨࡳࡓࠋࡑࡢ
Ohya landslide⤖ᯝ㸪␗࡞ࡿࢱ࢖ࣉࡢὶື໬ࡀ☜ㄆࡉࢀ㸪ࡲࡓᅵ▼ὶࡢከᆅⅬほ ࡟ᡂຌࡋࡓࡢ࡛ࡇࡇ࡟ሗ
V380 m
400࿌ࡍࡿࠋ
Ohya-Ohtaki fall䠎䠊◊✲ᑐ㇟ᆅ䛚䜘䜃◊✲᪉ἲ㻌ᅗ䠍㻌 ほ ᆅ࿘㎶䛾ᆅᙧᅗ䛸ᶵჾ䛾タ⨨఩⨨㻌኱㇂ᔂࡣ㸪᪥ᮏ୕኱ᔂࢀࡢࡦ࡜ࡘ࡟ᩘ࠼ࡽࢀ
8200
occurence of debris flowࡿ኱つᶍᔂቯᆅ࡛࠶ࡿࠋᮏ◊✲ࡣ኱㇂ᔂࡢ୰࡛
6150
ࡶ◁♟⏕⏘ࡀ᭱ࡶάⓎ࡛ᅵ▼ὶࡢⓎ⏕ᇦ࡜࡞ࡗ࡚࠸ࡿࠕ୍ࡢἑࠖୖὶᇦࢆᑐ㇟࡜ࡋ࡚ほ ࢆ
100
4⾜ࡗࡓ㸦ᅗ㸯㸧ࠋὶᇦෆࡣᵓ㐀㐠ື࡟ࡼࡿ᩿ᒙ࣭
〩᭤࡟ࡼࡗ࡚◚○ࡀ㐍ࢇ࡛࠾ࡾ㸪」㞧࡟ධࡾ⤌502
ࢇࡔ◁ᒾ࣭㡫ᒾࡀ㟢ฟࡋ࡚࠸ࡿࠋ
ࠕ୍ࡢἑࠖୖὶᇦෆ࡟㸪࣡࢖࣮ࣖࢭࣥࢧ࣮࡜
00
6:00
11:00
16:00
21:00
㐃ືࡋࡓࣅࢹ࣓࢜࢝ࣛࢆ 3 ⟠ᡤ㸦V1㹼V3㸧࡟ᅗ䠎㻌 ᅵ▼ὶ䛜Ⓨ⏕䛧䛯 㻞㻜㻝㻞 ᖺ 㻢 ᭶ 㻝㻥 ᪥䛾㝆㞵≧ἣ㻌タ⨨ࡋ࡚ᅵ▼ὶࡢ᧜ᙳࢆヨࡳࡓࠋࡲࡓ㸪ࣅࢹ࢜0࣓࢝ࣛ V1 ࡢ㏆ഐ࡟ࡣ㌿ಽ࣐ࢫᆺ㞵㔞ィࢆタ⨨ࡋ㸪㝆Ỉ㔞ࢆ 1 ศ㛫㝸࡛ほ ࡋࡓࠋ䠏䠊⤖ᯝ䛸⪃ᐹ㻌
3ほ ࡢ⤖ᯝ㸪2012 ᖺ 6 ᭶ 19 ᪥࡟Ⓨ⏕ࡋࡓ◁
V1 channel deposits♟ࡢὶືࢆ㸪V1 ࡜ V2 ࡟タ⨨ࡋࡓࣅࢹ࣓࢜࢝ࣛ
(P1)࡟ࡼࡗ࡚᧜ᙳࡍࡿࡇ࡜ࡀ࡛ࡁࡓࠋࡇࡢ࡜ࡁ V3 ࡣ࣓࢝ࣛࡢ୙ㄪ࡟ࡼࡾ᧜ᙳࡀ࡛ࡁ࡞࠿ࡗࡓࠋ
V1 talus slope(P2)䠏䠊䠍㻌 ୖὶഃ䠄㼂㻝䠅䛻䛚䛡䜛◁♟䛾ὶື㻌
V1 ࣓࢝ࣛ࡟࠾࠸࡚ὶື໬ࡀ᭱ึ࡟☜ㄆࡉࢀࡓ
V2ࡢࡣ 18 ᫬ 16 ศ࡛࠶ࡾ㸪㝆ࡾጞࡵ࠿ࡽࡢ⣼ຍ㞵
㔞 82.5 mm㸪ὶື໬㛤ጞ᫬ࡲ࡛ࡢ᭱኱ 10 ศ㛫㞵
18:00
18:10
18:20
18:30
㔞 4 mm ࡛࠶ࡗࡓ㸦ᅗ㸰㸧ࠋࡇࡢ࡜ࡁ㸪V1 ࣓࢝ᅗ䠏㻌 ὶື໬䛜ྛ䜹䝯䝷䛻䜘䛳䛶☜ㄆ䛥䜜䛯䝍䜲䝭䞁䜾㻌ࣛࡢ᧜ᙳ⠊ᅖ࡟ྵࡲࢀࡿ῱ᗋሁ✚≀㸦ᅗ 1 ࡢ P1㸧࡜ᓴ㗹㸦ྠ P2㸧ࡢ㸰⟠ᡤ࡟࠾࠸࡚ὶື໬ࢆ☜ㄆࡋࡓࠋࡉࡽ࡟ࡑࡢᚋ㸪P1 ࡛ 8 ᅇ㸪P2 ࡛ 7 ᅇࡢὶື໬ࢆ☜ㄆࡋࡓ㸦ᅗ㸱㸧
ࠋP1 ࡜ P2 ࡢ୧ᆅⅬ࡛☜ㄆࡉࢀࡓὶື໬࡟
┤᥋ⓗ࡞㛵ಀࡣ࡞ࡃ㸪ࡑࢀࡒࢀูࠎ࡟⏕㉳ࡋ࡚࠸ࡓࠋ
P1㸪P2 ࡜ࡶ࡟◁♟ࡀཌࡃሁ✚ࡍࡿሙᡤ࡛࠶ࡾ㸪ὶື໬Ⓨ⏕๓ࡣ㸪ୖὶ࠿ࡽࡢᆅ⾲ὶࡣ୧ᆅⅬ࡟ࡉࡋ࠿࠿ࡿ࡜ࡍ
࡭࡚ࡀᾐ㏱ࡋ࡚࠸ࡓࠋከࡃࡢὶື໬ࡣ㸪ୖὶ࠿ࡽࡢᆅ⾲

P2ὶࡢቑຍ࡟క࠸ᆅ⾲ὶࡢᾐ㏱ᆅⅬࡀᚎࠎ࡟ୗὶ࡬⛣ືࡋ㸪ࡸࡀ࡚ᆅ⾲ὶࡀሁ✚≀ࢆᕳࡁ㎸ࡴࡼ࠺࡟࡞ࡿࡇ࡜࡟P1ࡼࡾ㛤ጞࡉࢀࡓ㸦ᅗ㸲㸪ᅗ㸳a㸧ࠋࡇࡢࡼ࠺࡞౵㣗ࢱ࢖ࣉࡢὶື໬௨እ࡟ࡶ㸰ࡘࡢࢱ࢖ࣉࡢὶື໬ࡀ☜ㄆࡉࢀࡓࠋࡦ࡜ࡘࡣ P1 ࡛ 18 ᫬ 26 ศ࡟☜ㄆࡉࢀࡓࡶࡢ࡛࠶ࡾ㸪῱ᗋሁ✚≀ࡀ㞟ྜⓗ࡟⛣ືࢆ㛤ጞࡋࡓࡶࡢ࡛࠶ࡿ㸦ᅗ㸳ᅗ䠐㻌 㼂㻝 ᆅⅬ䛷᧜ᙳ䛥䜜䛯ὶື໬᫬䠄㻝㻤㻦㻞㻜䠅䛾⏬ീ㻌b㸧ࠋࡇࢀࡣᆅ⾲ὶ࡟ࡼࡗ࡚ᅵ◁⛣ືࡀ┤᥋ⓗ࡟ᘬࡁ㉳ࡇ䠄ⓑ䛔㡿ᇦ䛿ᆅ⾲ὶ䠈Ⅼ⥺䛿ὶື㛤ጞ㡿ᇦ䜢♧䛩䠅㻌ࡉࢀࡓࡶࡢ࡛ࡣ࡞ࡃ㸪ሁ✚≀ෆ㒊ࡢ㣬࿴㸪㛫㝽Ỉᅽࡢୖ᪼࡟క࠺ࡶࡢ࡛࠶ࡿ࡜⪃࠼ࡽࢀࡿࠋࡇࡢሙྜࡶ⾲㠃ὶࡣሁ✚≀࡬Ỉࢆ౪⤥ࡍࡿࡇ࡜࡛ὶື໬ ⾲㠃ὶὶື໬⾲㠃ὶ࡟ᐤ୚ࡋ࡚࠸ࡓ࡜⪃࠼ࡽࢀࡿࠋࡶ࠺ࡦ࡜ࡘࡣ 18
᫬ 27 ศ࡟ P2 ࡛☜ㄆࡉࢀࡓࡶࡢ࡛࠶ࡾ㸪ὶື㡿ᇦࡀୗὶഃ࠿ࡽୖὶഃ࡬ྥࡅ࡚㐳ୖࡋࡓࠋୗὶື໬‫ؚ‬ᆢ‫ם‬ჿሁ✚ᅵ◁‫ؚ‬ᆢ‫ם‬ჿሁ✚ᅵ◁ὶഃ࡛࠾ࡁࡓὶື໬ࡼࡿᆅᙧኚ໬ࡀୖὶഃࡢ

䠄㼍䠅⾲㠃ὶ䛻䜘䜛౵㣗㻌 㻌 㻌 㻌 㻌 㻌 㻌 㻌 䠄㼎䠅㞟ྜⓗ䛺⛣ື㻌ᅵ◁ࡢ୙Ᏻᐃ໬ࢆᘬࡁ㉳ࡇࡋࡓྍ⬟ᛶࡀ࠶ࡿࠋᅗ䠑㻌 ◁♟䛾ὶື໬䛾ᶍᘧᅗ㻌ከࡃࡢὶືࡣὶ㏿ࡀ 3 m/s ௨ୗ࡜㐜ࡃ㸪ࡲࡓᩘ 10m ⛬ᗘ⛣ືࡋࡓ࠶࡜࡟೵Ṇࡍࡿ࡞࡝㸪ὶືᛶ࡟ஈࡋ࠸ࠋࡦ࡜ࡘࡢὶືࡢ⥅⥆᫬㛫ࡣ 10 ⛊㹼2 ศ⛬ᗘ࡛࠶
ࡿࠋ18 ᫬ 20 ศ࠿ࡽ☜ㄆࡉࢀࡓ῱ᗋሁ✚≀ࡢὶື໬ࡣࡇࢀࡽࡢ≉ᚩ࡜␗࡞ࡾ㸪ὶ㏿ࡀ 3㹼5 m/s ⛬ᗘ㸪⥅⥆᫬㛫ࡀ 4 ศ⛬ᗘ࡛࠶ࡗࡓࠋࡇࡢὶື໬ࡀ⏕ࡌ࡚࠸ࡿ᫬㛫ᖏࡣ⾲㠃ὶ࡟ࡼࡾୖὶഃ࠿ࡽከ㔞ࡢỈࡀ౪⤥ࡉࢀ⥆ࡅ࡚࠾ࡾ㸪⏬ീࢆุㄞࡍࡿ㝈ࡾὶື໬ࡋࡓ◁♟࡟ྵࡲࢀࡿ㛫㝽ὶయ㸦ἾỈ㸧ࡢ๭ྜࡣ௚ࡼࡾࡶከ࠿ࡗࡓࠋὶື໬ࡢࢱ࢖࣑ࣥࢢ࡜▷ᮇⓗ࡞㝆㞵ᙉᗘࡢ㛫࡟ࡣ᫂☜࡞㛵ಀࡣࡳࡽࢀ࡞࠿ࡗࡓࠋὶື໬ࡀ࠾ࡁࡿ࡜౵㣗࣭ሁ✚࡟ࡼࡾᆅᙧࡀኚ໬ࡍࡿࡓࡵ㸪ḟࡢὶື໬ࡀ࠾ࡁࡿሙᡤࡣẖᅇᩘ m㹼ᩘ 10m ࡢ⠊ᅖ࡛⛣ືࡋ࡚࠸ࡓࠋ䠏䠊䠎㻌 ୗὶഃ䠄㼂䠎䠅䛻䛚䛡䜛◁♟䛾ὶື㻌 V2 ࣓࢝ࣛࡢ᧜ᙳ⠊ᅖࡣ V1 ࣓࢝ࣛࡢ᧜ᙳ⠊ᅖ࡜ẚ㍑ࡋ࡚῱ᗋሁ✚≀ࡀⷧࡃ㸪ᅵ▼ὶࡢ㠀ὶୗ᫬࡟࠾࠸࡚ࡶᖖ࡟ᆅ⾲ὶࡀ☜ㄆ࡛ࡁࡿࠋV2 ࣓࢝ࣛ࡟ࡼࡾ◁♟ࡢὶືࡀ☜ㄆࡉࢀࡓࡢࡣ 2 ᅇ࡛࠶ࡿ㸦ᅗ㸱㸧ࠋ᭱ึ࡟☜ㄆࡉࢀ
ࡓࡢࡣ 18 ᫬ 25 ศ࡛࠶ࡾ㸪V1 ࣓࡛࢝ࣛ᭱ึ࡟☜ㄆࡉࢀ࡚࠿ࡽ 9 ศᚋ࡛࠶ࡿࠋ18 ᫬ 25 ศ௨๓࡟ V2 ࣓࢝ࣛ࡟ࡼࡾ᧜ᙳࡉࢀࡓࡢࡣἾỈࡢࡳ࡛࠶ࡾ㸪V1 ࣓࡛࢝ࣛ᧜ᙳࡉࢀࡓ◁♟ࡢὶືࡣ V2 ࡢ᧜ᙳ⠊ᅖࡼࡾࡶୖὶഃ࡛ࡍ
࡭࡚೵Ṇࡋࡓࡇ࡜࡟࡞ࡿࠋ18 ᫬ 25 ศ௨㝆ࡶୖὶഃ㸦V1㸧࡜ୗὶഃ㸦V2㸧ࡢὶື☜ㄆ᫬㛫ࡣ࡯࡜ࢇ࡝୍⮴ࡋ࡚࠾ࡽࡎ㸪୧ᆅⅬ࡛ࡢὶືࡣ࡯࡜ࢇ࡝ࡀ୙㐃⥆ⓗ࡞ࡶࡢ࡛࠶ࡿ࡜᥎ᐹࡉࢀࡿࠋV2 ࣓࢝ࣛ࡟ࡼࡗ࡚ὶືࡀ☜ㄆࡉࢀࡓ◁♟ࡣ᧜ᙳ⠊ᅖࡢ῱ᗋ࡟௨๓࠿ࡽ࠶ࡗࡓࡶࡢ࡛ࡣ࡞ࡃ㸪ୖὶ࠿ࡽ㐠ࡤࢀ࡚ࡁ࡚ࡑࡢࡲࡲୗὶഃ࡬㐠ᦙࡉࢀ࡚࠸ࡃࡶࡢ㸪࠶ࡿ࠸ࡣ࠸ࡕ࡝᧜ᙳ⠊ᅖෆ࡟ሁ✚ࡋ࡚ᆅ⾲ὶ࡟ࡼࡾ෌⛣ືࡋ࡚࠸ࡃࡶࡢ࡛࠶ࡗࡓࠋ䠐䠊䛚䜟䜚䛻㻌 ᮏ◊✲࡟ࡼࡗ࡚㸪ᅵ▼ὶࡢⓎ⏕ᇦ࡛ࡣὶືᛶࡢஈࡋ࠸ᑠつᶍ࡞ᅵ◁ࡢ⛣ື࡜ᆅᙧኚ໬ࡀ⧞ࡾ㏉ࡉࢀ࡚࠸࡚࠸ࡿࡇ࡜㸪ࡑࡋ࡚㸱ࡘࡢࢱ࢖ࣉࡢὶື໬ࡀࡳࡽࢀࡿࡇ࡜ࡀ᫂ࡽ࠿࡟࡞ࡗࡓࠋࡲࡓ㸪◁♟ࡢὶື໬࡟ࡣᆅ⾲ὶࡀ኱ࡁ࡞ᙺ๭ࢆᯝࡓࡋ࡚࠸ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋ௒ᚋࡣᆅᙧィ ࡸỈᩥほ ࢆ⤌ࡳ࠶ࢃࡏ࡚࠸ࡃࡇ࡜࡛ᅵ▼ὶࡢⓎ⏕Ⓨ㐩ᶵᵓࡢゎ᫂ࢆ┠ᣦࡋ࡚࠸ࡁࡓ࠸ࠋᘬ⏝ᩥ⊩䠖㻌Ỉ㇂ኴ㑻࣭㔛῝ዲᩥ࣭ሐ ኱୕࣭Ỉᒣ㧗ஂ(2008)㸸ᛴ໙㓄῱ᗋሁ✚≀୰ࡢỈศືែ㸪◁㜵Ꮫ఍ㄅ Vol.61, No.3, p.27-30ᒣ⏣Ꮥ㸪᳃೺ྖ㸪἟ᮏ᫴ஓ㸪ᯘᣋ㑻(2009)㸸◁㜵࠼ࢇሐ᪋ᕤ᫬ࡢ῱ᗋሁ✚ᶓ᩿㠃ࢆά⏝ࡋࡓᅵ▼ὶⓎ⏕┤๓ࡲ࡛ࡢఅὶỈὶฟኚ໬㸪⾲㠃ὶⓎ⏕ࣉࣟࢭࢫࡢほ̽୕㔜┴࠸࡞࡭ᕷ⸨ཎᓅすஅ㈅ᡞᕝ࡛ࡢ஦౛̺㸪◁㜵Ꮫ఍ㄅ Vol.62, No.3, p.30-38

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