Title 1988 年雌阿寒岳の噴火活動に伴う地震活動の特性 Author(s) 高木, 朗充 Citation 北海道大学地球物理学研究報告 = Geophysical bulletin of Hokkaido Un Issue Date 29-3-15 DOI 1.14943/gbhu.72.331 Doc URL http://hdl.handle.net/2115/38163 Type bulletin (article) File Information 23_Takagi.pdf Instructions for use Hokkaido University Collection of Scholarly and Aca
332 高木 朗充 seismograms were the same direction. In order to explain these characteristics, we proposed the tensile crack model with Doppler effect. Ⅰ. はじめに 雌阿寒岳は北海道東部 (Fig. 1) の阿寒カルデラの西南壁上に噴出した安山岩質の火山で, 阿 寒富士を含めた 1 の噴出中心からなる複式火山の総称である. このうちポンマチネシリ火口及 びナカマチネシリ火口では活発な噴気活動が継続している. 雌阿寒岳の有史以降の明らかな火山活動は過去 1 年程度しか記録されていない. 記録に残 る活動は 1927 年の鳴動が最初である (横山 他, 1976). また地質学的研究から, 1955 年の 噴火活動までの約 1 年間に, 両火口から小規模な水蒸気爆発が少なくとも 1 回発生してい る (和田 他, 1997). 1954 1964 年には小噴火が断続的に発生し, 1956 年の噴火では南東 9km の浜中村茶内まで降灰が観測された (気象庁, 25). しかし, その後しばらく火山活動 は静穏な時期が続いた. 43.5 km 5 1 Oakandake L.Akan Fuppushidake Furebetsudake 43.4 Meakandake Nonaka spa a L.Onneto m 1 45 5 m 75 Akanfuji Akanfu A Ak Akanf fu f m 44 KNP SAPPORO TSK Meakandake 43 URH 42 14 43.3 143.9 144. 144.1 141 142 143 144 145 144.2 Topographic map around Meakandake volcano. Insert map shows locations of active volcanoes in Hokkaido, including Meakandake. A square box over Meakandake indicates the area of seismic observation in Fig. 3.
m Plume and Fumarole (Pon-machineshiri) 15 8 Max height 6 Average height 1 Temp. of fumarole 4 Eruption 2 5 1975 198 1985 199 1995 2 25 N / Month Earthquake (All) 1 8 6 4 2 1975 198 1985 199 1995 2 25 N / Month Deep Low Frequency Earthq. (TD,TS) 3 2 1 1975 198 1985 199 1995 2 25 after SMO,JMA
km.5 1 Latitude Longitude Height Code Component Gain Note [Deg.] [Deg.] [m] [db] P 144.838E 43.38161N 134 UD 42 Mark Products L4C 43.4 43.75 Nonaka spa 75m P4 P2 P3 1m P1 Naka -machinehsiri Pon -machinehsiri P 1st crater 125m Mt.Akanfuji 143.975 144. 144.25 P P2 P1 P3 P4 P1 143.99792E 43.39195N 98 UD 6 Mark Products L4C P2 143.9874E 43.393N 799 UD 6 Mark Products L4C P3 143.9977E 43.39363N 859 UD 6 Mark Products L4C P4 143.98649E 43.39523N39523N 731 UD,NS,EW 6 VOLCANO UD UD UD UD UD NS EW 5m 8m Pickup 1Hz 1m 3m 4m NONAKA SPA AMP /PCM MODEM DRUM 1mm/sec NTT TESHIKAGA RELAY NTT PCM. TELE. SYS. Katsushima PK-11 JMA Sismic Station SAPPORO all REAL TIME TREMOR MONITOR all Reprod. HDDR MT OPD DIGITAL DATA ANALOG DATA 18CH all PEN RECORDER 1mm/min LONG TERM P1 RECORDER 4mm/sec
RCEP (a) (b) µkine 4 3 2 1 N/DAY 2 15 1 5 JMA (c) N/DAY 15 (d) 1 5 Eruption 1987 1988 N/DAY 6 4 2 1987 1988 1987 1988 1987 1988 Tremor level P1 Earthquake (All) NO DATA Earthquake (All) 1/18 666 11/14 718 1/18 296 11/14 215 Deep Low Frequency Earthq. (TD,TS)
Number 1 N all (P2) = 1852 (a) μkine 1 1 Amplitude P1(UD) NO DATA 1 1 b-value = 1.57 1 1987 1988 (b) Hz 2 15 Dominant freq. P1(UD) NO DATA HF 1 1 1 2785 1 μkine 1 5 1987 1988 LF TD,TS,T
(a) µkine 1 Amplitude P2(UD) Eruption 1 1 NO DATA (b) 3. 2. 1. Amplitude ratio P2/P3 NO DATA 1987 December 1988 January
N 3 25 Dominant frequency of Simple event LF HF (a) LF 1988.1.18 11:1:39 P1(UD) 1691 μkine P2(UD) 1sec μkine 1 1 Spectrum P1 Max : 6.9 Hz 2 15 1 5 N = 1343 (P1) 5 1 15 Hz Frequency 1647 μkine P3(UD) 1165 μkine P4(UD) 123 μkine P4(EW) 216 μkine P4(NS) 1343 μkine (b) HF 1988.1.15 18:3:3 P1(UD) 1468 μkine P2(UD) 791 μkine P3(UD) 411 μkine P4(UD) 411 μkine P4(EW) 11 μkine P4(NS) 1325 μkine 1sec 1 1.1 1 1 1 Hz 1 μkine Spectrum P1 1 Max : 11.9 Hz 1 1 1 1.1 1 1 1 Hz
(a) TD µkine P1(UD) 1988.3.6 22:5:42 1sec 1 P1(UD) 87 µkine Max :.9 Hz 1 P2(UD) 6 µkine P3(UD) 1 49 µkine P4(UD) 46 µkine 1 KNP(UD) 16 µkine URH(UD).1 24 µkine.1 1 1 1 Hz µkine P1(UD) (b) TS 1 1.1 Hz 1988.7.25 4:13:27 1sec 1 5 µkine RCEP P1(UD) 391 µkine 1 1 JMA.5 µm A(UD).4 µm.1.1 1 1 1 Hz
LD P1(UD) 1988.11.13 2:52:11 2785 μkine 1sec T P4(UD) 1988.8.18 3:19:2 174 μkine Dominant freq. 1.6 Hz 1sec 1988.11.13 23:11:3 2785 μkine 1988.1.1 2:31:52 26 μkine Dominant freq. 1.1 Hz 1988.11.13 23:57:21 2148 μkine 1988.1.24 9:4:22 119 μkine Dominant freq. 1.4 Hz 1988.11.14 1:22:42 1561 μkine 1988.11.2 22:12:52 141 μkine Dominant freq. 1.4 Hz 1988.11.14 2:2:18 1311 μkine 1988.11.13 8:15:34 277 μkine Dominant freq. 1.4 Hz 1988.11.14 3:47:21 2785 μkine 1988.11.13 9:11:15 293 μkine Dominant freq. 1.4 Hz 1988.11.14 4:54:4 199 μkine 1988.11.14 5:7:1 1474 μkine Other P4(UD) 1988.1.31 13:5:37 826 μkine 1988.11.14 9:47:45 1349 μkine 1988.11.14 9:52:38 2785 μkine Remarkable phase HF LF 1988.1.15 18:3:3 1474 µmkine 1988.1.18 11:1:39 172 µkine 1sec 1sec 1sec Number 1988.1.25 5:41:5 1272 µkine PT 1sec 81 precursor TD 1988.3.6 22:5:42 173 µkine 1sec 48 1988.1.1 2:31:52 261 µkine TS 1sec 138 1988.11.14 9:52:38 2785 µkine LD 1sec 111 1988.11.13 9:11:15 212 µkine T 1sec 6 Total 2959 1sec
(a) (b) N 1 E N = 354 1 8 6 2 3 4 4 2 Pon 5 -machineshiri Number 2.5 5. 7.5 1. km/sec S Aparent velocity (a) (b) 15m 1m 5m m 25 NW H P4 2 15 1 Distance P3 Pon-machineshiri P1 D sec Travel time.8 Average.6.4.2 S. 5 225.9 S SE P V1 V2 V1=2.474km/sec V2=2.985km/sec H=274m
km 43.4 1 A N AZIMUTH 43.375 1m m -1m -2m -3m -4m 143.975 144. 144.25 144.5 A PROFILE 125m 1m PROFILE LINE km 1 B B 75m DIP 1 2 3 4 5 6 7 8 S 9 Naka -machineshiri E 1982 1987-1988 Pon -machineshiri
Number of earthquake Swarm Period All > 2 kine Family Ratio(%) A 1988/7/3-7/31 142 26 17 65 B 1988/8/15-8/16 38 17 12 71 C 1988/9/14-9/15 89 18 14 78 D 1988/1/18 8 666 51* 17* 33 * >4 kine (P1) Family Others Swarm A P1(UD) 1 sec 1988.7.31 :58:49 2785 µkine 1988.7.3 21:18:6 223 µkine 1988.7.3 22:41:45 277 µkine 1988.7.3 23:11:46 348 µkine 1988.7.3 23:38:58 734 µkine 1988.7.3 23:4:14 26 µkine 1988.7.3 23:52:5 25 µkine 1988.7.31 :29:24 31 µkine 1988.7.31 :36:36 696 µkine 1988.7.31 :42:4 826 µkine 1988.7.31 :47:52 239 µkine 1988.7.31 1:1:6 674 µkine 1988.7.31 1:15:34 348 µkine 1988.7.31 1:19:2 223 µkine 1988.7.31 1:35:45 952 µkine 1988.7.31 1:46:46 756 µkine 1988.7.31 1:56:11 359 µkine 1988.7.3 22:3:2 359 µkine 1988.7.3 22:3:32 674 µkine 1988.7.3 22:44:9 369 µkine 1988.7.3 22:49:28 277 µkine 1988.7.3 23:13:51 391 µkine 1988.7.3 23:32:32 315 µkine 1988.7.3 23:37:6 26 µkine 1988.7.31 2:12: 212 µkine 1988.7.31 2:45:34 32 µkine 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 11112131415161718192 212223242526 63 85 55 73 53 68 71 54 69 59 6 55 67 61 61 73 49 81 47 6 51 81 68 74 85 59 67 56 Cross correlation 69 52 79 69 61 7 6 76 1 82 68 78 77 7 66 59 83 65 11 79 7 79 77 7 65 66 86 7 81 12 83 66 81 71 78 62 7 77 68 81 87 13 85 52 82 68 78 62 69 67 65 73 74 84 14 81 56 76 72 69 66 57 75 67 77 71 75 74 15 84 64 85 76 76 62 77 81 7 82 88 86 79 68 16 8 56 81 69 68 59 66 74 66 76 77 75 69 8 74 17 71 45 78 66 56 6 55 68 63 66 64 66 65 69 67 75 18 4 26 42 36 5 41 42 39 37 38 35 48 54 35 41 3 35 19 43 41 38 44 41 32 35 46 44 43 36 37 46 35 4 29 31 81 2 38 22 46 49 4 32 28 33 62 3 33 45 43 53 31 39 36 3 24 21 52 47 51 48 47 39 38 49 44 53 53 48 46 58 49 6 69 36 3 38 22 64 38 6 55 53 58 42 6 53 59 55 54 56 68 55 61 56 42 42 53 39 23 57 45 61 55 41 47 69 58 47 53 64 62 43 46 67 63 52 21 2 28 41 37 24 26 13 2 16 3 11 22 15 29 17 18 2 22 24 18 18 15 13 1 34 16 17 15 25 34 39 27 22 29 32 38 31 15 32 34 33 25 22 41 32 2 22 16 12 21 28 45 11 26 16 17 2 2 14 18 15 2 11 16 19 13 15 14 19 15 19 17 15 13 16 16 15 26 1
Family A Family B Family C Family D P1(UD) 1 sec 1988.7.31 :47:52 239 µkine 1988.7.31 :58:49 2785 µkine 1988.7.31 1:1:6 674 µkine 1988.8.15 2:33:36 25 µkine 1988.8.15 22:35:36 25 µkine 1988.8.15 22:42:6 734 µkine 1988.9.14 1:31:53 261 µkine 1988.9.14 1:59:3 228 µkine 1988.9.14 12:2:36 598 µkine 1988.1.18 18:58:46 674 µkine 1988.1.18 19:55:36 186 µkine 1988.1.18 22:13:35 875 µkine Cross correlation A1A2A3 B1B2B3C1C2C3D1D2D3 A1 A2 A3 79 87 83 B1 2 24 16 B2 B3 16 16 24 17 19 13 88 88 83 C1 33 26 23 81 75 77 C2 C3 2 33 2 25 19 23 73 77 77 74 72 79 77 89 69 D1 6 67 63 2 14 18 19 2 19 D2 65 67 67 16 17 17 2 2 2 9 D3 63 67 66 15 13 14 17 21 19 94 9
Family Master event Incident wave All events (Number) Range of incident wave Cross-spectrum method Without this method AZI 147.1 AZI 14.1 151.3 136.7 154.7 A 1988.7.31 :58:49 (17) DIP 45.1 DIP 33.1 5.6 29. 54.7 B 1988.8.15 22:42:8 C 1988.9.14 12:2:36 AZI 137.7 AZI 13.5 137.7 123.7 144.5 (12) DIP 76.5 DIP 61.6 76.5 56.4 81.7 AZI 135.3 AZI 133.5 138. 121. 15.5 (14) DIP 69.7 DIP 67. 75.8 37.6 85.2 AZI 145.1 AZI 14.7 148.2 11.1 178.8 D 1988.1.18 19:55:36 (17) DIP 43.4 DIP 37.8 49.4 11.2 76. AZI : Azimuth angle from N clockwise. DIP : Dip angle from vertical.
LF 1988.11.8 :47:27 365 μkine 1 sec HF 1988.11.8 1:3:32 561 μkine FFT Window.7 sec Correlation Window 5 sec Cross correlation : 82% Normalized LF 5.8Hz Hz 1 1 1 Hz 1 1 1 Normalized HF 13.Hz