MIKROZONASI SEISMIK WILAYAH PADALARANG, KABUPATEN BANDUNG BARAT MENGGUNAKAN METODE HORIZONTAL TO VERTICAL SPECTRAL RATIO (HVSR)

Gabrio Hikma Januarta, Tedi Yudistira, Adrin Tohari, Erlangga Ibrahim Fattah

Abstract


Dalam kurun waktu lima tahun terakhir terjadi peningkatan aktivitas tektonik di wilayah selatan Pulau Jawa. Salah satu sesar aktif di wilayah Jawa Barat yaitu Sesar Cimandiri dan Sesar Lembang. Sesar Cimandiri berarah barat daya-timur laut, sedangkan Sesar Lembang berarah timur-barat. Melalui citra satelit DEM (Digital Elevation Model) pertemuan kedua sesar diduga berada di wilayah Padalarang, Kabupaten Bandung Barat. Keberadaan infrastruktur penghubung kota seperti jalan tol, rel kereta api serta permukiman penduduk yang padat menjadikan daerah tersebut merupakan daerah yang berpotensi mengalami kerusakaan saat terjadi gempa bumi. Dalam upaya mitigasi diperlukan studi mikrozonasi untuk mengetahui karakteristik  tanah. Metode Horizontal to Vertical Spectral Ratio (HViSR) digunakan untuk mengestimasi nilai frekuensi dominan (f0) dan faktor amplifikasi (A0) daerah setempat dari data pengukuran mikrotremor. Dari 42 titik pengukuran didapatkan nilai frekuensi dominan (f0) yang terbagi kedalam dua zona yaitu 1,4–3,5 Hz dan 3,5–6 Hz. Sedangkan nilai faktor amplifikasi (A0) berkisar antara 2–8. Nilai indeks kerentanan seismik (Kg) berkisar antara 1–30, daerah dengan indeks kerentanan seismik (Kg) sedang hingga tinggi berada di Kecamatan Ngamprah dan Kecamatan Cisarua, sedangkan indeks kerentanan seismik (Kg) pada daerah Kecamatan Padalarang relatif rendah hingga sedang.

ABSTRACT Seismic Microzonation of Padalarang District, West Bandung Regency Using Horizontal to Vertical Spectral Ratio (HVSR) Method.  In the last five years, tectonic activity has increased in the southern region of Java Island. One of the active faults in the West Java region is Cimandiri Fault and Lembang Fault. The Cimandiri Fault is southwest-northeast, while the Lembang Fault is east-west. Through DEM (Digital Elevation Model) satellite imagery, the intersection of the faults is probably located in Padalarang, West Bandung Regency. The existence of urban infrastructures such as toll roads, railways, and dense settlements makes this area have the potential to experience damage during an earthquake. Therefore, in mitigation efforts, microzonation studies are needed to determine the dynamic characteristics of soils in the area. Horizontal to Vertical Spectral Ratio (HVSR) method is used to estimate the value of dominant frequency (f0) and the amplification factor (A0) from microtremor measurement data. From 42 measurement points, the dominant frequency value (f0) is divided into two zones, 1.4–3.5 Hz and 3.5–6 Hz. The amplification factor (A0) ranges from 2–8. The value of the seismic vulnerability index (Kg) ranges from 1–30; areas with moderate to high seismic vulnerability indexes are in Ngamprah and Cisarua Districts, while the seismic vulnerability index in the Padalarang District is relatively low to moderate.

 


Keywords


microzonation, microtremor, HVSR, Lembang Fault, Cimandiri Fault

References


Daryono, 2013. Indeks kerentanan seismik berdasarkan mikrotremor pada setiap satuan bentuk lahan di zona Graben Bantul, Daerah Istimewa Yogyakarta. Jurnal Riset Daerah, XII(1), 1753-1777.

Daryono, M. R., Natawidjaja, D. H., Sapiie, B., Cummins, P., 2019. Earthquake geology of the Lembang Fault, West Java, Indonesia. Tectonophysics, 751, 180-191.

Mulyatno, B. S., Marjiyono, Setianegara, R., 2013. Penentuan zona rawan guncangan bencana gempa bumi berdasarkan analisis amplifikasi HVSR mikrotremor dan analisis periode dominan daerah Liwa dan sekitarnya. Geofisika Eksplorasi, 2(1), 30-40.

Nakamura, Y., 1989. A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. Quarterly Report Railway Tech. Res. Inst., 30, 25-30.

Nakamura, Y., 2000. Clear identification of fundamental idea of Nakamura’s technique and its application. The 14th World Conference on Earthquake Engineering, Auckland.

Parolai, S., Grunthal, G., Wahlstrom, R., 2007. Site-specific response spectra from the combination of microzonation with probabilistic seismic hazard assessment-An example for the Cologne (Germany) area. Soil Dynamics and Earthquake Engineering, 27(1), 49-59.

SESAME, 2004. Guidelines For The Implementation Of The H/V Spectral Ratio Technique on Ambient Vibrations. Europe: SESAME European research project.

Silitonga P. H., 1973, Peta Geologi Lembar Bandung, Jawa, Pusat Penelitian dan Pengembangan Geologi, Dirjen Geologi dan Sumberdaya Mineral,Bandung

Sudjatmiko, 1972. Peta Geologi Lembar Cianjur, Jawa, skala 1:100.000. Direktorat Geologi, Bandung.

Sunardi, B., Daryono, Arifin, J., Susilanto, P., 2012. Kajian potensi bahaya gempa bumi daerah Sumbawa berdasarkan efek tapak lokal. Jurnal Meteorologi dan Geofisika, 13(2), 131-137.

Sungkono, 2011. Inversi terpisah dan simultan dispersi gelombang Rayleigh dan Horizontal-to-Vertical Spectra Ratio menggunakan algoritma genetik, Tesis, Institut Teknologi Sepuluh November, Surabaya.

Van Bemmelen, R.W. 1934. Geological of Bandung. Bandung: Geologi Tata Lingkungan

Van Bemmelen, R.W., 1949. The Geology of Indonesia. Government Printing Office, The Hague, Netherlands (732 p).




DOI: http://dx.doi.org/10.14203/risetgeotam2020.v30.1087

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