Ramadhani, Ivana Dzakiyyah (2024) Ketidakpastian Model Kecepatan Gelombang Geser dari Inversi Gelombang Permukaan dengan Metode Spatial Autocorrelation dari Mikrotremor dengan Konfigurasi Segitiga Terhadap Analisis Respon Tanah (Studi Kasus: Taman Alumni ITS). Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Surabaya terletak di antara sesar aktif yaitu Sesar Waru dan Surabaya, kedua sesar ter-sebut memiliki potensi gempa bumi yang besar dengan skala 6,5 Ritcher yang menyebabkan kerusakan ringan hingga berat tergantung kekuatan gempa. Institut Teknologi Sepuluh Nopember merupakan salah satu perguruan tinggi yang berada di Indonesia yang terletak di Surabaya, Jawa Timur. Sebagai upaya untuk mengantisipasi potensi bencana dan resiko ter-hadap gempa bumi. Ditinjau dari pengukuran mikrotremor oleh penelitian terdahulu didapatkan hasil kedalaman yang terbatas di lingkungan ITS. Maka dari itu, dilakukan pengukuran berulang dengan harapan untuk mendapatkan kedalaman yang lebih signifikan dengan menambah panjang lintasan dan titik lokasi ukur. Selain itu, pada penelitian ini juga menen-tukkan ketidakpastian model dan inversi beserta galatnya. Analisa data mikrotremor dengan pengukuran konfigurasi segitiga dilakukan dengan menerapkan metode Spatial Autocorrela-tion (SPAC). Dari analisis data mikrotremor diperoleh kurva dispersi dengan galat yang selan-jutnya digunakan untuk inversi profil kecepatan geser dengan ketidakpastiaannya. Hasil penelitian yang didapatkan berupa ketidakpastian model kecepatan gelombang geser terhadap kedalaman, di mana lapisan satu diperoleh kedalaman sekitar 9 meter dengan CoV sebesar 3% serta kecepatan gelombang geser sekitar 86 – 90 m/s dengan CoV sebesar 2%. Pada lapisan dua, kecepatan gelombang geser sekitar 236 – 282 m/s dengan CoV sebesar 9%. Sedangkan, penelitian terdahulu dengan konfigurasi segitiga pada lapisan satu diperoleh kedalaman sekitar 5,54 meter dengan kecepatan gelombang geser 83 m/s dan lapisan dua sebesar 249 m/s. Dengan menambah jarak lintasan dan titik ukur lokasi pada konfigurasi segitiga tidak terlalu menghasilkan kedalaman yang signifikan. Respons tanah yang didapatkan berupa nilai maksi-mum Pseudo Spectral Acceleration dari 0,8 – 1,05 g, nilai maksimum Fourier Amplitude Ratio dari 2,2 – 2,46 dan nilai Peak Ground Acceleration sekitar 0,29 – 0,33 g. Dari analisa respons tanah tersebut, disimpulkan bahwa semakin tinggi ketidakpastian kecepatan gelombang geser, maka semakin besar ketidakpastian faktor amplifikasi. Dari hasil tersebut, daerah penelitian akan mengalami penguatan amplifikasi yang cukup tinggi, sehingga dapat menyebabkan kerusakan sedang.
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Surabaya is located between active faults, namely the Waru and Surabaya Faults, both of which have the potential for large earthquakes with a scale of 6.5 Ritcher that cause minor to severe damage depending on the strength of the earthquake. Institut Teknologi Sepuluh Nopember is one of the universities in Indonesia located in Surabaya, East Java. As an effort to anticipate potential disasters and risks to earthquakes, microtremor measurements by previ-ous research obtained limited depth results in the ITS environment. Therefore, repeated meas-urements were carried out in the hope of obtaining a more significant depth by increasing the length of the track and measuring location points. In addition, this study also determines the uncertainty of the model and inversion along with the error. Microtremor data analysis with triangular configuration measurements was carried out by applying the Spatial Autocorrelation (SPAC) method. From the analysis of microtremor data, a dispersion curve with errors is ob-tained, which is then used for the inversion of the shear velocity profile with its uncertainty. The results obtained are the uncertainty of the shear wave velocity model to depth, where lay-er one obtained a depth of about 9 meters with a CoV of 3% and a shear wave velocity of about 86 - 90 m/s with a CoV of 2%. In layer two, the shear wave velocity is around 236 - 282 m/s with a CoV of 9%. Meanwhile, previous research with a triangular configuration in layer one obtained a depth of about 5.54 meters with a shear wave velocity of 83 m/s and layer two of 249 m/s. By increasing the distance of the trajectory and the location of the measuring point in the triangular configuration, it does not produce a significant depth. The ground re-sponse obtained is the maximum value of Pseudo Spectral Acceleration from 0.8 - 1.05 g, the maximum value of Fourier Amplitude Ratio from 2.2 - 2.46 and the Peak Ground Accelera-tion value around 0.29 - 0.33 g. From the ground response analysis, it is concluded that the higher the uncertainty of shear wave velocity, the greater the uncertainty of the amplification factor. From these results, the study area will experience a fairly high amplification gain, so it can cause moderate damage.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Analisis Respons Tanah, Autokorelasi Spasial, Gelombang Geser, Inversi Kurva Dispersi, Ketidakpastian, Ground Response Analysis, Spatial Autocorrelation, Shear Waves, Dispersion Curve Inversion, Uncertainty |
| Subjects: | G Geography. Anthropology. Recreation > G Geography (General) G Geography. Anthropology. Recreation > G Geography (General) > G70.212 ArcGIS. Geographic information systems. G Geography. Anthropology. Recreation > GB Physical geography G Geography. Anthropology. Recreation > GC Oceanography G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > QC Physics > QC20.7.F67 Fourier transformations |
| Divisions: | Faculty of Science and Data Analytics (SCIENTICS) > Physics > 45201-(S1) Undergraduate Thesis |
| Depositing User: | Ivana Dzakiyyah Ramadhani |
| Date Deposited: | 19 Feb 2024 03:30 |
| Last Modified: | 19 Feb 2024 03:30 |
| URI: | http://repository.its.ac.id/id/eprint/107438 |
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