Electronic Theses and Dissertation

Telah dilakukan penelitian Mikrotremor yang berlokasikan di Kota Sabang Pulau
Weh, sebnayak 64 titik. Penelitian dilakukan karena daerah ini terdapat 9 sesar dan
terhubung dengan patahan Sumatera yaitu Segmen Seulimum yang dimana
bergerak sekitar 34 mm pertahun. Tujuan dari penelitian ini adalah untuk
menjelaskan persebaran kerentanan tanah di Kota Sabang dan menjelaskan
karakteristik batuan di Kota Sabang berdasarkan variabel kerentanan seismik.
Sinyal hasil akuisisi diolah dengan software geopsy untuk menentukan frekuensi
dominan (f0) dan faktor amplifikasi (A0). Selanjutnya Indeks Kerentanan Seismik
(Kg) didapatkan berdasarkan perhitungan empiris dan penentuan kecepatan
gelombang geser (Vs) menggunakan kurva HVSR sebagai input metode elipsitas
berdasrkan proses inversi software dinver. Hasil penelitian nilai faktor amplifikasi
(A0) diperoleh pada rentang 0,05 – 3,06. Hasil penelitian nilai frekuensi dominan
(f0) diperoleh pada rentang 1,13 – 8,78 Hz. Hasil penelitian nilai indeks kerentanan
seismik (Kg) diperoleh pada rentang 0,1 – 5,59. Nilai indeks kerentanan seismik
yang tinggi terkonsentrasi pada daerah yang cenderung litologi penyusunannya
ialah batuan lunak. Hasil nilai kecepatan rata-rata gelombang geser pada kedalaman
30 meter (Vs30) diperoleh pada rentang 69,02 – 630,86 m/s. Nilai Vs30
diklasifikasikan berdasarkan klasifikasi tanah berdasarkan NEHRP (National
Earthquake Hazard Reduction Program) diperoleh nilai rata-rata Vs30 pada daerah
penelitian didominasi oleh Tanah Sedang (D) dan tanah lunak (E).
Kata Kunci: Mikrotremor, Quasi Transfer Spectrum, Frekuensi Dominan, Faktor
Amplifikasi, Indeks Kerentanan Seismik, Kecepatan Gelombang
Geser

A microtremor study was conducted at 64 points in Sabang City, Weh Island. This research was carried out due to the presence of 9 faults in the area and its connection to the Sumatran fault, specifically the Seulimuum Segment, which is moving at a rate of approximately 34 mm per year. The objectives of this study were to explain the distribution of soil vulnerability in Sabang City and to characterize the rocks in Sabang City based on seismic vulnerability variables. The acquired signals were processed using the Quasi-Transfer Spectrum method with Geopsy software to determine the dominant frequency (f0) and amplification factor (A0). Subsequently, the Seismic Vulnerability Index (Kg) was obtained based on empirical calculations and the determination of shear wave velocity (Vs) using the HVSR curve as input for the ellipticity method based on the Dinver software inversion process. The research results showed that the amplification factor (A0) values ranged from 0.05 to 3.06. The dominant frequency (f0) values ranged from 1.13 to 8.78 Hz. The seismic vulnerability index (Kg) values ranged from 0.1 to 5.59. High seismic vulnerability index values were concentrated in areas with a tendency to have soft rock lithology. The average shear wave velocity at a depth of 30 meters (Vs30) ranged from 69.02 to 630.86 m/s. Based on the NEHRP (National Earthquake Hazard Reduction Program) soil classification, the average Vs30 values in the study area were dominated by Class D (intermediate soil) and Class E (soft soil). Keywords: Microtremor, Quasi Transfer Spectrum, Dominant Frequency, Amplification, Seismic Vulnerability, Shear Wave Velocity