Electronic Theses and Dissertation

Penelitian dilakukan di Kecamatan Baitussalam, Aceh Besar menggunakan metode geolistrik resistivitas dan seismik refraksi yang bertujuan untuk mengetahui litologi bawah permukaan serta membandingkan respon perlapisan batuan berdasarkan nilai resistivitas dan cepat rambat gelombang. Data geolistrik resistivitas diperoleh dari instrumen SuperSting R8/IP dengan panjang bentangan 165 m. Data seismik refraksi dilakukan dengan instrumen seismograf PASI 16S-24P pada bentangan sepanjang 69 m. Hasil menunjukkan bawah permukaan daerah penelitian teridentifikasi tiga lapisan. Setiap lapisan diwakili oleh nilai resistivitas dan cepat rambat gelombang P (Vp) yang berbeda tergantung pada jenis batuan. Litologi batuannya terdiri dari pasir lempungan (ρ= 30 - 215 Ωm, Vp = 0.4 – 1.2 km/s), lempung (ρ= 1-100 Ωm, Vp = 1.2 – 2.4 km/s), dan batupasir (ρ= 2 - 3500 Ωm, Vp = 2.2 – 3.4 km/s). Hasil perbandingan antara kedua metode menunjukkan lapisan bawah permukaan menampilkan dimensi yang serupa, namun tampak beberapa perbedaan pada area tertentu yang disebabkan oleh perbedaan respon dari setiap lapisan berdasarkan metode yang digunakan. Respon metode geolistrik dikontrol oleh konduktivitas material serta kandungan lempung. Sementara metode seismik refraksi sangat bergantung oleh respon tingkat kepadatan batuan.

Kata kunci: geolistrik resistivitas, seismik refraksi, investigasi geoteknik, lapisan bawah permukaan, kedalaman investigasi

Research has been conducted at Baitussalam Regency, Aceh Besar using geolectrical resistivity and seismic refraction methods which aims to determined the ground subsurface lithology and compare the respon of rock layers based on resistivity and P-wave velocity values. Geolectrical resistivity data were acquired using SuperSting R8/IP instrument with 165 meters long. The seismic refraction data conducted using seismograph PASI 16S-24P instrument with 69 meters long. The results showed that the subsurface of the study area identified of three layers. Each layer was represented by different resistivity and P-wave velocity (Vp) values depending on the rock type. The rock lithology was composed of sand clay (ρ= 30 - 215 Ωm, Vp = 0.4 – 1.2 km/s), clay (ρ= 1-100 Ωm, Vp = 1.2 – 2.4 km/s), and sandstone (ρ= 2 - 3500 Ωm, Vp = 2.2 – 3.4 km/s). The comparison results between the two methods showed that subsurface layers display the similar dimension, but there were some differences in certain areas due to the difference respon of each layer based on the method that were used. The response of the geoelectric method is controlled by the conductivity of the material and the clay content. While the seismic refraction method is highly dependent on the response of the rock density level. Keyword: geoelectrical resistivity, seismic refraction, geotechnical investigation, ground subsurface layer, investigation depth