Laporan Metode Plus Minus
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Transcript of Laporan Metode Plus Minus
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KEMENTERIAN DIKTI DAN RISTEK
PROGRAM STUDI GEOFISIKA JURUSAN FISIKA
FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM
UNIVERSITAS GADJAH MADA
PRAKTIKUM METODE SEISMIK I
METODE DELAY TIME (PLUS MINUS)
DISUSUN OLEH :
RAHMI ZAFIRA AMINI
12/334809/PA/15019
DOSEN PENGAMPU :
Dr. EDDY HARTANTYO, S.Si., M.Si.
YOGYAKARTA
OKTOBER
2015
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I. DATA
Picking Data Lintasan B Flat Picking Data Lintasan B Flat (Noisy)
Waktu (ms)
Topografi
(m)
Waktu (ms)
Topografi
(m)
Shot 1 2 3 4 Shot 1 2 3 4
Posisi
(m) 5 78 152 225
Posisi
(m) 5 78 152 225
0 15.4 181.8 257.8 350.7 100 0 16.4 177.9 256.3 350 100
10 15.4 163.9 239.9 332.8 100 10 16.6 163.5 239.5 333.3 100
20 46.2 145.9 221.9 314.8 100 20 48.2 146.1 221.2 317 100
30 76.9 129.9 205.9 298.8 100 30 77.7 128.6 207.1 303.5 100
40 107.7 115.6 191.6 284.5 100 40 105.8 118 191.5 286.4 100
50 138.5 87.2 178.8 271.7 100 50 138 87.1 182.3 275.2 100
60 155.4 56.4 165.7 258.6 100 60 154.3 55.3 165.2 254.7 100
70 165.9 25.6 150.4 243.3 100 70 164.9 25.1 155.7 242.2 100
80 174 5.1 133.8 226.7 100 80 175.1 4.8 134 227.4 100
90 180.4 35.9 116.4 209.3 100 90 181.6 34.1 120.4 207.5 100
100 185.8 66.7 99.2 192.2 100 100 185.8 70.5 99.7 190.4 100
110 192.4 80.3 83.5 176.4 100 110 196.5 80.7 84.6 176.8 100
120 201.3 89.2 69.6 162.5 100 120 203.3 89.2 71.5 159.1 100
130 212.6 100.6 58.7 151.6 100 130 211.6 102 61.5 151.6 100
140 229 116.9 35.9 145.9 100 140 227.1 114.3 37.9 147.6 100
150 246 134 5.1 139.6 100 150 246.5 134.2 5.2 142.6 100
160 263.1 151.1 25.6 133.8 100 160 259.9 150.9 26 134.4 100
170 280.1 168.1 56.4 125.6 100 170 283.2 170.6 53.6 125.1 100
180 295.2 183.2 87.2 115.1 100 180 294.6 185 88 116.7 100
190 308.3 196.2 105.2 103.1 100 190 310.1 195.7 104.3 103.3 100
200 319.8 207.7 116.7 76.9 100 200 323.6 206.6 117.7 80.6 100
210 329.4 217.3 126.3 46.2 100 210 329.1 219.5 129 49.4 100
220 338.2 226.2 135.2 15.4 100 220 339.1 226 138.2 16.9 100
230 344.4 232.3 141.4 15.4 100 230 344.1 233.9 141.8 16.3 100
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II. PENGOLAHAN
a. Pengolahan Data Lintasan B
SP1 – SP2
Equation V1 (m/s) Source to source time
Direct Forward y = 3.077x - 15.37 V1 F 324.9919 Forward 174.3
Refract Forward y = 1.05x + 92.4 V1 R 332.4468 Reverse 171.005
Direct Reverse y = -3.008x + 236.64 V1 328.7193 Average 172.6525
Refract Reverse y = -1.609x + 179.05
C
Travel time T-Minus
T plus V 1 V 2 hD ForwardT SD (s)
ReverseT S’D (s)
T SD - T S’D
0 15.4 181.8 -166.4 24.5475 328.7193419 752.162467 4.4856723
5 97.65 171.005 -73.355 96.0025 328.7193419 752.162467 17.5429577
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10 102.9 163.9 -61 94.1475 328.7193419 752.162467 17.2039854
20 113.4 145.9 -32.5 86.6475 328.7193419 752.162467 15.8334776
30 123.9 129.9 -6 81.1475 328.7193419 752.162467 14.8284385
40 134.4 114.69 19.71 76.4375 328.7193419 752.162467 13.9677595
50 144.9 98.6 46.3 70.8475 328.7193419 752.162467 12.9462743
60 155.4 82.51 72.89 65.2575 328.7193419 752.162467 11.9247891
70 165.9 66.42 99.48 59.6675 328.7193419 752.162467 10.9033039
78 174.3 53.548 120.752 55.1955 328.7193419 752.162467 10.0861157
SP2 –
SP3
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Equation V1 (m/s) Source to source time
Direct Forward y = 3.08x - 241.3 V1 F 324.6753 Forward 133.922
Refract Forward y = 1.351x - 71.43 V1 R 373.1343 Reverse 135.986
Direct Reverse y = -2.68x + 408.43 V1 348.9048 Average 134.954
Refract Reverse y = -1.613x + 261.8
C
Travel time T-Minus
T plus V 1 V 2 hD ForwardT SD (s)
ReverseT S’D (s)
T SD - T S’D
78 33.948 135.986 -102.038 34.98 348.9048265 674.763833 7.12941780 36.65 133.8 -97.15 35.496 348.9048265 674.763833 7.234585
90 50.16 116.4 -66.24 31.606 348.9048265 674.763833 6.441748
100 63.67 99.2 -35.53 27.916 348.9048265 674.763833 5.689674
110 80.3 83.5 -3.2 28.846 348.9048265 674.763833 5.879221
120 89.2 69.6 19.6 23.846 348.9048265 674.763833 4.860151
130 100.6 52.11 48.49 17.756 348.9048265 674.763833 3.618923
140 116.9 35.98 80.92 17.926 348.9048265 674.763833 3.653571
150 134 19.85 114.15 18.896 348.9048265 674.763833 3.851271
152 133.922 16.624 117.298 15.592 348.9048265 674.763833 3.177869
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SP3 – SP4
Equation V1 (m/s) Source to source time
Direct Forward y = 3.08x - 467.2 V1 F 324.6753 Forward 140.77
Refract Forward y = 0.996x - 83.33 V1 R 340.3676 Reverse 142.998
Direct Reverse y = -2.938x + 662.69 V1 332.5215 Average 141.884
Refract Reverse y = -1.026x + 298.95
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C
Travel time T-Minus
T plus V 1 V 2 hD ForwardT SD (s)
ReverseT S’D (s) T SD - T
S’D
152 68.062 142.998 -74.936 69.176 332.5214608 989.119683 12.21202
160 76.03 133.8 -57.77 67.946 332.5214608 989.119683 11.99488
170 85.99 125.6 -39.61 69.706 332.5214608 989.119683 12.30558
180 95.95 115.1 -19.15 69.166 332.5214608 989.119683 12.21025
190 105.2 104.01 1.19 67.326 332.5214608 989.119683 11.88542
200 116.7 93.75 22.95 68.566 332.5214608 989.119683 12.10433
210 126.3 83.49 42.81 67.906 332.5214608 989.119683 11.98782
220 135.2 73.23 61.97 66.546 332.5214608 989.119683 11.74773
225 140.77 68.1 72.67 66.986 332.5214608 989.119683 11.8254230 141.4 15.4 126 14.916 332.5214608 989.119683 2.633203
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SP1 – SP4
Equation V1 (m/s) Source to source time
Direct Forward y = 3.077x - 15.37 V1 F 324.9919 Forward 343.5405
Refract Forward y = 1.2203x + 68.973 V1 R 340.3676 Reverse 326.691
Direct Reverse y = -2.938x + 662.69 V1 332.6797 Average 335.11575
Refract Reverse y = -1.2858x + 333.12
C
Travel time T-Minus
T plus V 1 V 2 hD ForwardT SD (s)
ReverseT S’D (s)
T SD - T S’D
0 15.4 350.7 -335.3 30.98425 332.6797361 795.038957 5.674605
5 75.0745 326.691 -251.6165 66.64975 332.6797361 795.038957 12.20656
10 81.176 332.8 -251.624 78.86025 332.6797361 795.038957 14.44285
20 93.379 314.8 -221.421 73.06325 332.6797361 795.038957 13.38115
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30 105.582 298.8 -193.218 69.26625 332.6797361 795.038957 12.68575
40 117.785 284.5 -166.715 67.16925 332.6797361 795.038957 12.3017
50 129.988 271.7 -141.712 66.57225 332.6797361 795.038957 12.19236
60 155.4 258.6 -103.2 78.88425 332.6797361 795.038957 14.44724
70 165.9 243.3 -77.4 74.08425 332.6797361 795.038957 13.56815
80 174 226.7 -52.7 65.58425 332.6797361 795.038957 12.01141
90 180.4 209.3 -28.9 54.58425 332.6797361 795.038957 9.996822
100 185.8 192.2 -6.4 42.88425 332.6797361 795.038957 7.854028
110 192.4 176.4 16 33.68425 332.6797361 795.038957 6.169095
120 201.3 162.5 38.8 28.68425 332.6797361 795.038957 5.253371
130 212.6 151.6 61 29.08425 332.6797361 795.038957 5.326629
140 229 145.9 83.1 39.78425 332.6797361 795.038957 7.286279
150 246 139.6 106.4 50.48425 332.6797361 795.038957 9.245928
160 263.1 133.8 129.3 61.78425 332.6797361 795.038957 11.31546
170 280.1 125.6 154.5 70.58425 332.6797361 795.038957 12.92714
180 295.2 115.1 180.1 75.18425 332.6797361 795.038957 13.76961
190 308.3 88.818 219.482 62.00225 332.6797361 795.038957 11.35539
200 319.8 75.96 243.84 60.64425 332.6797361 795.038957 11.10668
210 329.4 63.102 266.298 57.38625 332.6797361 795.038957 10.50999
220 338.2 50.244 287.956 53.32825 332.6797361 795.038957 9.766792
225 343.5405 43.815 299.7255 52.23975 332.6797361 795.038957 9.567439
230 344.4 15.4 329 24.68425 332.6797361 795.038957 4.520792
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b. Pengolahan Data Lintasan B (Noisy)
SP1 – SP2
Equation V1 (m/s) Source to source time
Direct Forward y = 3.004x - 12.86 V1 F 332.8895 Forward 173.38
Refract Forward y = 1.06x + 90.7 V1 R 322.0612 Reverse 169.85
Direct Reverse y = -3.105x + 242.15 V1 327.4753 Average 171.615
Refract Reverse y = -1.54x + 177.55
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C
Travel time T-Minus
T plus V 1 V 2 hD ForwardT SD (s)
ReverseT S’D (s)
T SD - T S’D
0 16.4 177.9 -161.5 22.685 327.4753362 769.289945 4.104881
5 96 169.85 -73.85 94.235 327.4753362 769.289945 17.05195
10 101.3 163.5 -62.2 93.185 327.4753362 769.289945 16.86195
20 111.9 146.1 -34.2 86.385 327.4753362 769.289945 15.63148
30 122.5 128.6 -6.1 79.485 327.4753362 769.289945 14.38292
40 133.1 115.95 17.15 77.435 327.4753362 769.289945 14.01197
50 143.7 100.55 43.15 72.635 327.4753362 769.289945 13.1434
60 154.3 85.15 69.15 67.835 327.4753362 769.289945 12.27483
70 164.9 69.75 95.15 63.035 327.4753362 769.289945 11.40627
78 173.38 57.43 115.95 59.195 327.4753362 769.289945 10.71141
SP2 – SP3
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Equation V1 (m/s) Source to source time
Direct Forward y = 3.285x - 259.18 V1 F 304.414 Forward 133.142
Refract Forward y = 1.321x - 67.65 V1 R 355.2398 Reverse 137.416
Direct Reverse y = -2.815x + 428.97 V1 329.8269 Average 135.279
Refract Reverse y = -1.608x + 262.84
C
Travel time T-Minus
T plus V 1 V 2 hD ForwardT SD (s) Reverse
T S’D (s)
T SD - T S’D
78 35.388 137.416 -102.028 37.525 329.826895 682.826903 7.067561
80 38.03 134 -95.97 36.751 329.826895 682.826903 6.921783
90 51.24 120.4 -69.16 36.361 329.826895 682.826903 6.84833
100 64.45 99.7 -35.25 28.871 329.826895 682.826903 5.437643
110 80.7 84.6 -3.9 30.021 329.826895 682.826903 5.654237
120 89.2 71.5 17.7 25.421 329.826895 682.826903 4.78786
130 102 53.8 48.2 20.521 329.826895 682.826903 3.864981
140 114.3 37.72 76.58 16.741 329.826895 682.826903 3.153045
150 134.2 21.64 112.56 20.561 329.826895 682.826903 3.872515
152 133.142 18.424 114.718 16.287 329.826895 682.826903 3.067538
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SP3 – SP4
Equation V1 (m/s) Source to source time
Direct Forward y = 3.1x - 471.13 V1 F 344.3526 Forward 144.9
Refract Forward y = 1.13x - 109.35 V1 R 322.5806 Reverse 143.266
Direct Reverse y = -2.904x + 657.87 V1 333.4666 Average 144.083
Refract Reverse y = -1.017x + 297.85
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C
Travel time T-Minus
T plus V 1 V 2 hD ForwardT SD (s)
ReverseT S’D (s)
T SD - T S’D
152 62.41 143.266 -80.856 61.593 333.4666311 931.532371 10.99847
160 71.45 134.4 -62.95 61.767 333.4666311 931.532371 11.02954
170 82.75 125.1 -42.35 63.767 333.4666311 931.532371 11.38667
180 94.05 116.7 -22.65 66.667 333.4666311 931.532371 11.90451
190 104.3 104.62 -0.32 64.837 333.4666311 931.532371 11.57774
200 117.7 94.45 23.25 68.067 333.4666311 931.532371 12.15451
210 129 84.28 44.72 69.197 333.4666311 931.532371 12.35629
220 138.2 74.11 64.09 68.227 333.4666311 931.532371 12.18308
225 144.9 69.025 75.875 69.842 333.4666311 931.532371 12.47146
230 141.8 16.3 125.5 14.017 333.4666311 931.532371 2.502971
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SP1 – SP4
Equation V1 (m/s) Source to source time
Direct Forward y = 3.004x - 12.86 V1 F 332.8895 Forward 344.626
Refract Forward y = 1.2266x + 68.641 V1 R 344.3526 Reverse 329.4775
Direct Reverse y = -2.904x + 657.87 V1 338.621 Average 337.05175
Refract Reverse y = -1.3205x + 336.08
C
Travel time T-Minus
T plus V 1 V 2 hD ForwardT SD (s)
ReverseT S’D (s)
T SD - T S’D
0 16.4 350 -333.6 29.34825 338.6210489 785.175879 5.507466
5 74.774 329.4775 -254.7035 67.19975 338.6210489 785.175879 12.61064
10 80.907 333.3 -252.393 77.15525 338.6210489 785.175879 14.47888
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20 93.173 317 -223.827 73.12125 338.6210489 785.175879 13.72187
30 105.439 303.5 -198.061 71.88725 338.6210489 785.175879 13.4903
40 117.705 286.4 -168.695 67.05325 338.6210489 785.175879 12.58315
50 129.971 275.2 -145.229 68.11925 338.6210489 785.175879 12.7832
60 154.3 254.7 -100.4 71.94825 338.6210489 785.175879 13.50174
70 164.9 242.2 -77.3 70.04825 338.6210489 785.175879 13.14519
80 175.1 227.4 -52.3 65.44825 338.6210489 785.175879 12.28196
90 181.6 207.5 -25.9 52.04825 338.6210489 785.175879 9.767327
100 185.8 190.4 -4.6 39.14825 338.6210489 785.175879 7.346525
110 196.5 176.8 19.7 36.24825 338.6210489 785.175879 6.802313
120 203.3 159.1 44.2 25.34825 338.6210489 785.175879 4.756829
130 211.6 151.6 60 26.14825 338.6210489 785.175879 4.906957
140 227.1 147.6 79.5 37.64825 338.6210489 785.175879 7.065036
150 246.5 142.6 103.9 52.04825 338.6210489 785.175879 9.767327
160 259.9 134.4 125.5 57.24825 338.6210489 785.175879 10.74315
170 283.2 125.1 158.1 71.24825 338.6210489 785.175879 13.37038
180 294.6 116.7 177.9 74.24825 338.6210489 785.175879 13.93336
190 310.1 85.185 224.915 58.23325 338.6210489 785.175879 10.928
200 323.6 71.98 251.62 58.52825 338.6210489 785.175879 10.98336
210 329.1 58.775 270.325 50.82325 338.6210489 785.175879 9.537444
220 339.1 45.57 293.53 47.61825 338.6210489 785.175879 8.935997
225 344.626 38.9675 305.6585 46.54175 338.6210489 785.175879 8.733982
230 344.1 16.3 327.8 23.34825 338.6210489 785.175879 4.381511
III. PEMBAHASAN
Dalam interpretasi metode plus minus, asumsi awal adalah refraktor memiliki
permukaan yang irregular atau berundulasi sehingga terdapat beda waktu/tambahan waktu
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Dari hasil pengolahan tersebut, terlihat bahwa meskipun data sedikit noisy, tapi tidak terlalu
mempengaruhi hasil. Trend kemiringan dari model yang dihasilkan sama dengan model hasil
pengolahan data yang tidak noisy. Hanya saja pada model terlihat lebih jelas undulasinya.
IV.KESIMPULAN
Metode plus minus dapat digunakan untuk mencari ketebalan lapisan lapuk (weathered
layer).
Metode plus minus mengasumsikan bahwa refraktor memiliki permukaan yang
irregular atau berundulasi sehingga terdapat beda waktu/tambahan waktu (delay time)
penjalaraan gelombang saat mengalami refraksi jika dibandingkan dengan saat
gelombang melalui refraktor yang miring tanpa berundulasi.
Nilai beda waktu (delay time) berbanding lurus dengan kedalaman refraktor, sehingga
jika nilainya semakin besar maka lapisan akan semakin dalam.
V. REFERENSI
Hartantyo Eddy. 2002. Modul Praktikum Seismik Refraksi (Bias) Beserta Analisis
Komputasi Numeriknya. Yogyakarta: Laboratorium Geofisika FMIPA UGM.