Mukhbitah, Sukma Putri (2023) Estimasi Kecepatan Gelombang Geser dan Respons Tanah Menggunakan Metode Spatial Autocorrelation Mikrotremor dengan Konfigurasi L dan Segitiga di ITS Surabaya. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Secara geografis dan geologis, Surabaya sangat rentan terhadap bencana dan risiko gempa bumi. Maka dari itu, diperlukan kesiapan untuk menghadapi keadaan darurat dan risiko akibat bencana gempa di lingkungan ITS Surabaya. Pada penelitian ini dilakukan analisis data mikrotremor menggunakan metode spatial autocorrelation (SPAC) untuk mendapatkan kurva dispersi. Akuisisi data mikrotremor dilakukan dengan perangkat lunak STnet di Lapangan Futsal PLN ITS menggunakan konfigurasi L dan segitiga. Selain itu, digunakan pula variasi geofon dengan frekuensi 4,5 dan 10 Hz. Dari akuisisi data, didapatkan data berupa rekaman sinyal mikrotremor untuk setiap variasi. Data tersebut kemudian diolah dengan perangkat lunak Geopsy, Hvinv, dan DeepSoil. Berdasarkan pengolahan data, konfigurasi segitiga menghasilkan kurva dispersi yang lebih baik dibandingkan dengan kofigurasi L, yaitu mampu menghasilkan kurva dispersi dengan rentang frekuensi yang lebih lebar. Geofon 4,5 dan 10 Hz menghasilkan kurva dispersi yang identik di frekuensi tinggi. Namun pada frekuensi rendah, geofon 10 Hz mampu menghasilkan respon yang lebih baik dibandingkan frekuensi 4,5 Hz. Didapatkan pula model terbaik kecepatan gelombang geser (Vs) dan kedalaman untuk setiap lapisan di ITS. Lapisan satu memiliki nilai Vs yang berada pada rentang 78 – 85 m/detik dengan kedalaman 5 – 6 m, sedangkan lapisan dua berada pada rentang 178 – 269 m/detik. Model terbaik tersebut digunakan untuk menganalisis respons tanah 1D dengan pendekatan linear menggunakan domain frekuensi. Analisis pendekatan linear menghasilkan parameter-parameter yang dapat menggambarkan respons tanah terhadap gelombang seismik, seperti Peak Ground Acceleration (PGA), Pseudo Spectral Acceleration (PSA) redaman 5%, dan Fourier Amplitude Ratio (FAR). Semakin tinggi perbedaan nilai Vs tiap lapisan, maka kenaikan PGA, PSA, dan FAR juga semakin tinggi.
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Geographically and geologically, Surabaya is very vulnerable to disasters and earthquake risks. Therefore, readiness is needed to deal with emergencies and risks due to earthquake disasters in the ITS Surabaya environment. In this study, microtremor data analysis was performed using the spatial autocorrelation (SPAC) method to obtain the dispersion curve. Microtremor data acquisition was carried out using the STnet software at the PLN ITS Futsal Field using the L and triangle configurations. In addition, variations of geophones with frequencies of 4.5 and 10 Hz are also used. From data acquisition, data is obtained in the form of recordings of microtremor signals for each variation. The data is then processed using Geopsy, Hvinv, and DeepSoil software. Based on data processing, the triangular configuration produces a better dispersion curve compared to the L configuration, which is capable of producing a dispersion curve with a wider frequency range. The 4.5 and 10 Hz geophones produce a dispersion curve that is identical to the high frequencies. However, at low frequencies, the 10 Hz geophone is able to produce a better response than the 4.5 Hz frequency. Also obtained the best model of shear wave velocity (Vs) and depth for each layer in ITS. Layer one has Vs values in the range 78 – 85 m/sec with a depth of 5 – 6 m, while layer two is in the range 178 – 269 m/sec. The best model is used to analyze the 1D ground response with a linear approach using the frequency domain. Analysis of the linear approach produces parameters that can describe the response of the ground to seismic waves, such as Peak Ground Acceleration (PGA), 5% attenuation Pseudo Spectral Acceleration (PSA), and Fourier Amplitude Ratio (FAR). The higher the difference in Vs values for each layer, the higher the increase in PGA, PSA, and FAR.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Dispersion Curve, Microtremor, Soil Response Analysis, Shear Wave, SPAC, Analisis respons tanah, Kurva dispersi, Gelombang Geser, Mikrotremor |
| Subjects: | Q Science Q Science > QC Physics |
| Divisions: | Faculty of Science and Data Analytics (SCIENTICS) > Physics > 45201-(S1) Undergraduate Thesis |
| Depositing User: | Sukma Putri Mukhbitah |
| Date Deposited: | 29 Aug 2023 01:52 |
| Last Modified: | 29 Aug 2023 01:52 |
| URI: | http://repository.its.ac.id/id/eprint/102589 |
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