The study was conducted at the coastal area of Aceh Besar and Banda Aceh using 2-D resistivity and IP methods to investigate the changes/response of resistivity and chargeability toward sediment. The study is aimed to identify the post-, pre-and tsunami sediment deposits. The results are validated with hand auger performed on the study line. Generally, the study identified that the coastal sediments of Aceh Besar and Banda Aceh consist of clay/silty clay/sand/silty sand. Based on the results, the sediments are categorized into three layers; the top layer (post-tsunami sediment), tsunami sediments and pre-tsunami sediments. The tsunami sediment consists of a mix of sand or clay or silty clay or silty sand. Each layer was represented by different resistivity and chargeability values depending on the sediment types.

A geophysical investigation has been conducted on the road to assess the subsurface soil characteristics. The study investigates the causes of road failure around the body of the damaged roads in the main street of Alue Naga, Syiah Kuala, Banda Aceh to determine the variations of rocks charge ability and resistivity value of the subsurface of the study area. The method employed for this study was 2D Electrical Resistivity and Induced Polarization (IP) method with using Wenner-Schlumberger array. Two profiles covering a distance of 100 meters each were established parallel to the road pavement along the stable and unstable sections of the road. Data were collected along the two profiles using ABEM Terra meter SAS 4000. The observed field data were processed and inverted using 2-D modelling inversion algorithm (RES2DINV Software). The result shows the presence of low resistivity and charge ability value at several parts of both line 1 and line 2. Both lines observed the 0-1.73 msec of charge ability value and <1 ohm.m of resistivity value; those values were interpreted as alluvium. In conclusion, the low resistivity and charge ability value present that the area investigation was a layer of permeable, especially in the central part which was cohesive, and led to the instability and weakness of the load-carrying capacity.

This study was conducted in Banda Aceh district by utilizing seismic refraction P- and S-waves methods on three similar profile lines, with the aim to identify subsurface characteristic. The seismic data were acquired using ABEM TERRALOC MK8 system with 28 Hz vertical and 6 Hz horizontal geophones, and suitable seismic sources. Software used for processing to produce 2-D tomography sections and interpretations are IXRefract, Microsoft Excel, SeisOpt@2D v6.0 and Surfer 8. The results show the study area comprises of four subsurface layers with strong to very strong relation between Vp and Vs (R2 is >0.7509) for each layer. Ratio value of Vp and Vs (Vp/Vs) for each layer (1st to 4th) was calculated to be 4.75 – 5.79; 6.50 – 8.89; 6.57 – 12.17 and 6.08 – 8.21 respectively. This study concluded that the ground subsurface in Banda Aceh district is made up of water saturated unconsolidated sediments that was identified to be a mixture of clay and silt at depth up to 55 m.

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One of the global geohazard issues discuss among scientists is soil liquefaction phenomenon. The incidents occurred at Palu in September 2018 and Aceh in December 2004, triggered soil liquefaction phenomenon which lead severe damages and lives. The common research on the geohazard issue include geotechnical methods (SPT and CPT) and geophysical methods (MASW and seismic). This study was conducted at Meuraxa district (Banda Aceh) and Baitussalam district (Aceh Besar) to introduce the capability of Electrical Resistivity Tomography (ERT) to predict the soil liquefaction phenomenon. The 2-D resistivity data were process using res2dinv inversion software to produce resistivity inversion models which then correlated with published results. The study identified that the resistivity values of 0.1 -10 Ωm is a soil saturated zone which affected by seawater intrusion and concludes that the study areas predicted by ERT have a high potential of soil liquefaction phenomenon to be occurred.

Penelitian untuk mengidentifikasi keberadaan air tanah dan kedalaman akuifer telah dilakukan di wilayah KEK Arun Lhokseumawe Provinsi Aceh dengan kondisi geologi daerah penelitian adalah batuan lanauan dan batuan lempung serta geomorfologinya berupa perkebunan dan sungai buatan. Penelitian ini mengaplikasikan metode geolistrik resistivitas 2D dengan konfigurasi Wenner-Schlumberger. Akuisisi data di lapangan menggunakan alat SuperSting R8 yang keseluruhannya mempunyai 4 lintasan pengukuran dengan lintasan 1 dan 2 memotong lintasan 3 dan 4, panjang masing-masing lintasan pengukuran tersebut adalah 400 m. Pemprosesan data Hasil akuisisi di lapangan menggunakan software Res2dinv untuk menampilkan model 2D bawah permukaan di lokasi penelitian. Hasil interpretasi menunjukkan lintasan L1 pada kedalaman sampai dengan 70 m terdapat lempung berpasir, lanauan dan gravel. Terdapatnya pengaruh instrusi air laut pada kedalaman 25 m yang ditandai dengan nilai resistivitas 1 Ώm. Lapisan akuifer di identifikasi pada jarak bentangan 100 - 200 m dan pada kedalaman 60 m dengan nilai resistivitas 30 Ωm. Penampang lintasan 3 dan 4 tidak menunjukkan adanya lapisan akuifer yang layak untuk diexploitasi pada lintasan tersebut. Interpretasi lintasan L4 menunjukkan adanya intrusi air laut yang besar pada lapisan pertama. Terdapat 3 lapisan yang kontras yaitu lapisan lempung berpasir, gravel/lempung lanauan dan batuan dasar. Lapisan akuifer pada lintasan 4 diinterpretasikan berada pada kedalaman 70 m dengan nilai resistivitas 30 Ωm. Rekomendasi yang paling layak untuk lokasi pengeboran yaitu pada lintasan 4 pada jarak bentangan 180 m dengan jenis akuifer tertekan. The research to identified ground water and depth of aquifer was conducted in KEK Arun Lhokseumawe Aceh Province. The geology contained siltstone and clay with geomorphology area are plantation and artificial river. The 2D resistivity acquisition was using Supersting R8 equipment with Wenner-Schlumberger array. There are 4 survey lines that conducted in the area where line 1 and 2 were crossed with line 3 and 4. The length of each line is 400 m respectively. The data processing was using Res2dinv software to shows 2D subsurface model. The result shown that line 1 is sandy clay, siltstone and gravel at depths up to 70 m. It was influenced by sea water at depth 25 m with resistivity value of 1 Ωm. The aquifer layer was identified at depth 60 m with resistivity value of 30 Ωm. However, line 3 and 4 were presented that the area surveys are suitable for exploration which have not indicate the existence of an aquifer layer. In the last line, it shown sea water intrusion at the first layer. There are 3 layers that contained in line 4 which is clayey sand, gravel and bedrock. The aquifer layer at Line 4 was interpreted at depth 70 m with resistivity value of 30 Ωm. The most feasible recommendation for a drilling location is on Line L4 at a distance of 180 m with a confined aquifer type. Keywords: Aquifer, Resistivity, Lhokseumawe, ground water, sand

No abstract

Research of resistivity method at campus II Universitas Syiah Kuala has been conducted with the SuperSting 68 instrument. There were three lines, each 330 meters long with a spacing of 6 meters. The purpose of the research was to determine the depth of the bedrock at campus II of Universitas Syiah Kuala. The results showed that there was a conductive and resistive coating with a resistivity value of between 2–1250 Ωm. The rock types were composed of water-saturated rocks, Tuffs sandstone, and andesite. The supposed bedrock rock is an andesite rock with a resistivity of 170-1250 Ωm with good density. In conclusion, the separation between the sediment and the bedrock was visible at a depth of up 10 meters across the measuring track.