Pemanfaatan Frekuensi Alamiah Tanah Menggunakan Pengukuran Mikrotremor Tiga Komponen dalam Mendeteksi Kedalaman Batuan Dasar
DOI:
https://doi.org/10.20956/geocelebes.v5i2.14996Keywords:
HVSR, mikrotremor, site effectAbstract
Suatu wilayah yang memiliki kondisi geologi yang sama dapat memberikan respon yang berbeda terhadap efek getaran tanah, bergantung pada karakteristik batuan penyusun formasi di wilayah itu. Fenomena ini disebut site effect. Spektra ambient noise yang diperoleh dari pengukuran mikrotremor dapat digunakan untuk menentukan respon suatu site khususnya frekuensi dominan lapisan sedimen. Respon frekuensi ini berhubungan dengan ketebalan lapisan sedimen. Berdasarkan formasi geologinya, Kota Palu tersusun atas endapan aluvium berumur holosen yang menjadi sedimen penyusun paling muda di wilayah tersebut. Penelitian ini bertujuan untuk memperoleh estimasi ketebalan lapisan sedimen di tiga titik pengukuran mikrotremor dari nilai spektrum horizontal to vertical () yang merempresentasi frekuensi dominan (f0) serta kecepatan gelombang geser (Vs) lapisan sedimen. Hasil yang diperoleh memperlihatkan nilai frekuensi dominan tanah f0 <2.5 Hz, hasil inversi kurva HVSR memperlihatkan variasi ketebalan sedimen (Vs < 750 m/s) antara 152 – 186 m yang mengindikasikan lapisan sedimen penyusunnya masuk dalam kategori tebal, sedangkan variasi nilai Vs30 berada antara rentang 291 – 381 m/s. Hasil penelitian ini dapat digunakan sebagai dasar acuan untuk tujuan geoteknik, seperti desain bangunan tahan gempabumi berdasarkan respon frekuensi dominan tanah serta kecepatan gelombang gesernya.Downloads
References
Atashband, S., and Esfanizadeh, M. 2012. Effects Evaluation of Ambient Vibration Recording Conditions on HVTFA Results. In Proceedings of the 15th World Conference on Earthquake Engineering.
Badan Geologi. 2018. Di Balik Pesona Palu. Kementerian Energi dan Sumber Daya Mineral.
BMKG. 2018. Ulasan Guncangan Tanah Akibat Gempabumi Donggala 28 September 2018.
Hakim, A.C., Pramono, S., Warnana, D.D., Rochman, J.P.G.N., and Rahmatullah, F.S. 2019. Determination of Ground Profile and Peak Surface Acceleration (PSA) using single station microtremor Inversion method for earthquake hazard zonation of Lombok Island. IOP Conf. Series: Earth and Environmental Science. 389. https://doi.org/10.1088/1755-1315/389/1/012045
Harsuko, M.R.C., Zulfakriza, Nugraha, A.D., Sarjan, A.F.N., Widiyantoro, S., Rosalia, S., Puspito, N.T., and Sahara, D.P. 2020. Investigation of Hilbert – Huang Transform and Fourier Transform for Investigation of Hilbert – Huang Transform and Fourier Transform for Horizontal-to-Vertical Spectral Ratio Analysis: Understanding the Shallow Structure in Mataram City, Lombok, Indon. Frontiers in Earth Science. 8(334). https://doi.org/10.3389/feart.2020.00334.
Kanai, K. 1983. Engineering Seismology. Tokyo: University of Tokyo Press.
Konno, K., and Ohmachi, T. 1998. Ground-Motion Characteristics Estimated from Spectral Ratio between Horizontal and Vertical Components of Microtremor. Bulletin of the Seismological Society of America. 88(1), pp.228 – 241. https://doi.org/10.1785/BSSA0880010228
Nakamura, Y. 2000. Clear identification of fundamental idea of Nakamura’s technique and its applications. In: Proceedings of the 12th World Conference on Earthquake Engineering, 2656. http://www.sdr.co.jp/papers/n_tech_and_application.pdf
Pramono, S., Prakoso, W.A., Cummins, P., Rahayu, A., Rudyanto, A., Syukur, F., and Sofian. 2017. Investigation of subsurface characteristics by using a Vs30 parameter and a combination of the HVSR and SPAC methods for microtremor arrays. International Journal of Technology. 8(6), 983–992. https://doi.org/10.14716/ijtech.v8i6.682
Riantana, R., Darsono., and Triyono, A. 2019. Design of Microtremor Monitoring Tools Using Accelerometer Sensor on Android Mobile to Determine the Natural Building Frequency in UNS Library. Journal of Physics: Conf. Series. 1204. https://doi.org/10.1088/1742-6596/1204/1/012103
Rusydi, M., Efendi, R., Sandra., and Rahmawati. 2018. Earthquake Hazard Analysis Use Vs30 Data in Palu. Journal of Physics: Conference Series. 979. https://doi.org/10.1088/1742-6596/979/1/012054
Sambridge, M. 1999. Geophysical inversion with a neighbourhood algorithm — I . Searching a parameter space. Geophys. J. Int. 138, pp. 479 –494. https://doi.org/10.1046/j.1365-246X.1999.00876.x
SESAME. 2004. Guidelines For the Implementation of the H/V Spectral Ratio Technique on Ambient Vibrations Measurements, Processing and Interpretation. SESAME European research project.
Sunardi, B., Naimah, S., Haryoko, U., Rohadi, S., Sulastri., and Rasmid. 2018. Vs30 Mapping and Soil Classification in the Southern Part of Kulon Progo Using Rayleigh Wave Ellipticity Inversion. Journal of Geospatial Information Science and Engineering. 1(2), 58–64. https://doi.org/10.22146/jgise.39780
Syahruddin, M. H., Aswad, S., Palullungan, E.F., Maria, & Syamsuddin. 2014. Penentuan Profil Ketebalan Sedimen Lintas Kota Makassar Dengan Mikrotremor. Jurnal Fisika. 4(1), pp.17–25. https://journal.unnes.ac.id/nju/index.php/jf/article/view/3861
Thein, P.S., Pramumijoyo, S., Brotopuspito, K.S., Kiyono, J., Wilopo, W., Furukawa, A., and Setianto, A. 2014. Estimation of seismic ground motion and shaking parameters based on microtremor measurements at Palu city, Central Sulawesi province, Indonesia. International Journal of Geological and Environmental Engineering. 8(5), pp.308–319. https://doi.org/10.5281/zenodo.1092938
Valeria, R., Rustadi, Zaenudin, A., and Sulaeman, C. 2019. Karakteristik Tanah di Daerah Cekungan Bandung Berdasarkan Kecepatan Gelombang Geser (Vs30) dengan Metode MASW (Multichannel Analysis of Surface Wave). Jurnal Geofisika Eksplorasi. 3(1), pp.57-70. http://journal.eng.unila.ac.id/index.php/geo/article/view/1031
Wibowo, N.B., Sembri, J.N., Darmawan, D., Sumardi, Y., Afriliani, F., and Mahmudah, S. 2018. Intepretasi Lapisan Sedimen berdasarkan Ground Profile Vs dengan Pengukuran Mikrotremor di Kecamatan Pacitan. Indonesian Journal of Applied Physics. 8(1), pp.32-42. https://doi.org/10.13057/ijap.v8i1.14986
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