Maulidina, Miftakhul (2015) Analisa struktur bawah permukaan tanah di sekitar Candi Gambar Wetan, Kabupaten Blitar dengan metode Very Low Frequency Electromagnetic (VLF-EM). Masters thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Penelitian struktur bawah permukaan tanah di sekitar Candi Gambar
Wetan yang bertempat di Desa Sumberasri, Kecamatan Nglegok, Kabupaten
Blitar bertujuan untuk mengetahui anomali dan menentukan sebaran batuan
bawah permukaan sekitar candi. Metode yang digunakan adalah metode Very Low
Frequency Electromagnetic (VLF-EM). Pengambilan data di lapangan dilakukan
dengan membagi area menjadi beberapa lintasan. Spasi antarlintasan sebesar 1m.
Perekaman data VLF dilakukan di tiap titik pada masing-masing lintasan dengan
spasi antartitik sebesar 0.5 meter. Hasil akusisi atau perekaman data VLF berupa
nilai inphase,quadrature,t-field, dan tilt. Data tersebut diolah menggunakan
filtering NA-MEMD untuk menguraikan sinyal berfrekuensi tinggi hingga rendah
sehingga dapat menghilangkan noise. Selanjutnya, data tersebut diolah
menggunakan Filter Karous Hjelt untuk interpretasi kualitatif, yaitu menentukan
letak anomali yang lebih konduktif dan resesif. Selain itu, data juga diinversi
menggunakan software Inv2DVLF-v1 untuk interpretasi kuantitatif, yaitu
melakukan estimasi nilai resistivitas semu berdasarkan data inphase dan
quadrature. Setelah itu, keduanya digabung menjadi interpretasi keseluruhan.
Berdasarkan hasil penelitian yang telah dilakukan pada 9 line, sebagian besar
teridentifikasi anomali resistif yang diduga adalah batuan andesit dengan
resistivitas berkisar 120-220 Ωm pada kedalaman 0-40 meter. Hasil penelitian ini
diharapkan dapat membantu dalam menemukan arca atau sedimen-sedimen
batuan yang masih terpendam di dalam tanah karena candi induknya hingga saat
ini belum ditemukan.
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A geophysical investigation to study anomalies and determine the
distribution of rocks within the subsurface using the Very Low Frequency
Electromagnetic (VLF-EM) method was conducted around Gambar Wetan
temple. We have measured subsurface structure by dividing the area into several
tracks. The spacing of trajectory is 1 meter. The measurement was done at each
point on each trajectory with spacing of 0.5 meters. As a result, we get the data of
inphase, quadrature, t-fields, and tilt. Noise-Assisted Multivariate Empirical Mode
Decomposition (NA-MEMD) was applied to the data to denoise the signal of
VLF-EM data. The NA-MEMD filtered data were then interpreted qualitatively
using Karous-Hjelt filter to get the location of the anomaly which is more
conductive or more resistive. Quantitative interpretation using Inv2DVLF-v1 for
the inversion of tipper data (inphase and quadrature) were also done to get the
apparent resistivity profile. Then, both were combined to get the overall
interpretation. The results showed that there are generally two anomalies detected
around the temple in 9 lines measurement, conductive and resistive anomaly. The
resistive anomaly predicted as andesit has a resistivity 120-200 Ωm at depth of 0-
40 meters. This is expected to help in finding rocks within the subsurface because
the main temple has not been found.
| Item Type: | Thesis (Masters) |
|---|---|
| Additional Information: | RTFi 551.21 Mau a |
| Uncontrolled Keywords: | VLF-EM; Sedimen batuan; NA-MEMD; Filter Karous Hjelt; Inversi |
| Subjects: | Q Science > QE Geology > QE471 Sedimentary rocks. Sedimentology |
| Divisions: | Faculty of Mathematics and Science > Physics > 45101-(S2) Master Thesis |
| Depositing User: | - Taufiq Rahmanu |
| Date Deposited: | 03 Jul 2019 07:25 |
| Last Modified: | 03 Jul 2019 07:25 |
| URI: | http://repository.its.ac.id/id/eprint/63434 |
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