Mimin Iryanti

Sliding zone identification of landslide area using resistivity method in Cijambe, Subang West Java

Subang is an area which consists of hill and mountain. This area is also categorized as disaster-prone zone. An environment assessment should be carried out to prevent the landslide in the future. Sliding zone was associated with clay stones that were indicated by low resistivity zone. Technical measurements of resistivity method made are lateral mapping using the Wenner configuration with electrode spacing of 2 meter to reach the end point of the track along 60 meter. Resistivity values obtained in the range of 15-35 Ωm, 30-215 Ωm, and 250-1700 Ωm which indicated clay mixed with rock layer that dominates below the surface, clay sandy and alluvial were gathered. From the two dimension model, it can be concluded that in the study area reveal the sliding zone was located on upper the low resistivity zone.

Graben Structure Identification Using Gravity Method

Graben (trench) is a natural expanse that is lower in altitude compared to its surrounding which is caused by normal faults shift. Changes in rock density can be identified to obtain the subsurface rock structure. Gravity method is a basic method yet very effective in determining subsurface rock structure. Identification of graben structure is the main focus of this research in order to identify the natural resources which may be available under the ground. Research work was performed in various locations in Bogor and according to our analysis using 2D Talwani model, the average density at the surface is 2.5 gram/cm3. 2D modelling results show a fault structure at rocks with relative direction West-East. The fault is forming an extension block faulting which makes the area a graben. In general, the crosssection profile of the model indicates rock layer structure made from limestone rocks (2.75 gr/cm3), sands, flakes, limestone (2.5 gr/cm3), volcanic sediment layer sandstone (2.3 gr/cm3), and clay layer and similar (2.00 - 2.10 gr/cm3).

Resistivity mapping and geochemical data for groundwater contamination at Sarimukti municipal landfill, West Bandung

Opened dumping landfill system at the Municipal landfill Sarimukti, West Bandung has a possibility in related to the existence of leachates contamination, especially for shallow groundwater. Earth resistivity measured with 3 profiles resistivity survey on Wenner array and measurement of electrics conductivity of geochemistry samples its converted become water formation resistivity were conducted to delineate the spreading of leachates contamination by using empirical relationship. Leachates have been identified by resistivity range 0,61 – 6,3 Ωm with 6u2005m depth. However, result of geochemistry samples test and 2D resistivity profiles at surrounding civilian residences still have unclear in terms of leachates contamination to groundwater. High resistive rocks on imaging show that leachates are not possible to penetrate the shallow groundwater. But, this result is still early prediction to confirm a contamination to groundwater due to the age of landfill. Then, it needs improvement data continuously to monit...

Geoelectric imaging for saline water intrusion in Geopark zone of Ciletuh Bay, Indonesia

Saline water intrusion in estuary is an urgent ecological encounter across the world. The Ciletuh Bay, located in the southern Sukabumi district, is an area with high cultivated potential becoming one of the most important geology tourism zones in Indonesia. However, salt water intrusion along the creek is a natural spectacle that disturbs the economic growth of the whole region. This research was intended at plotting the subsurface level of saltwater interventions into aquifers at the northern part of Ciletuh creek, Indonesia. The study implemented geoelectric imaging methods. 37 imaging datum were acquired using Wenner array configuration. The saline water were identified across the study area. The result of two dimensional cross-sectional resistivity shows that there is an indication of sea content in our measured soil, i.e. the smallest resistivity value is 0.579 Ωm found at a depth of 12.4 m to 19.8 m at a track length of 35 m to 60 m is categorized in the clayey which shows low groundwater quality. However, when compared with the results of direct observation of groundwater from the wells of residents, the water obtained is brackish water. A water chemistry test is conducted to ascertain the initial results of this method so that a potential sea intrusion potential map can be interpreted more clearly. This can consequently help as an extrapolative model to define depth to saline water at any site within the saline water zone in the study area.

Mapping Landslide Potential Area using Fault Fracture Density Analysis on Unmanned Aerial Vehicle (UAV) Image

Photogrammetry with fault fracture density analysis adds high-resolution image of surface structure so that landslide potential of research area can be mapped comprehensively. The main notion in this paper is to distinguish regions and excerpt individual components from an unmanned aerial vehicle (UAV) image comparing to satellite image. Using Chan-Vese segmentation approaches to, we detect regions around the edge around the images. This paper presents an effective initialization method for segmentation using the Chan-Vese model by varying on the iteration. The method is tested on several models and provides considerable rise in performance. Finally, we developed program in Matlab for unravelling resulting equation numerically in fault zone case.

Analisis Sebaran Mineral Logam Pada Sedimentasi Batuan Di Daerah Kertajadi, Cidaun, Kabupaten Cianjur, Jawa Barat Menggunakan Metoda Geomagnet

Cidaun merupakan salah satu daerah pesisir pantai selatan yang terletak pada Kabupaten Cinajur Provinsi Jawa Barat. Salah satu kelebihan dari daerah pesisir pantai selatan Pulau Jawa adalah terdapat banyaknya mineral logam penghasil besi yang tersebar luas di sepanjang pesisir pantai. Oleh karena itu dilakukanlah eksplorasi untuk memetakan sebaran mineral logam yang ada di daerah Cidaun. Dalam melakukan eksplorasi mineral logam dibutuhkan suatu metode yang paling efektif yaitu eksplorasi geofisika dengan menggunakan metode geomagnet. Proses pengolahan data pada metode geomagnet dilakukan dengan menghitung nilai anomali magnetik dari medan magnetik total yang telah dilakukan koreksi terhadap koreksi harian dan koreksi IGRF. Kemudian dengan metode inversi data yang telah didapat dijadikan sebuah model. Selain itu dilakukan juga interpretasi kualitatif dan interpretasi kuantitatif. Interperetasi kualitatif dilakukan pada data yang telah dimodelkan menggunakan software surfer 11 , apabila data tersebut terdapat anomali magnetik bernilai sangat tinggi yang berdekatan dengan nilai anomali magnetik bernilai rendah atau perubahan nilai anomali terjadi secara signifikan kemudian dilakukan proses interpretasi secara kuantitatif. Interpretasi kuantitatif pada penelitian ini dengan dilakukan deliniasi berupa proses sayatan pada perbedaan nilai anomali magnetik yang terjadi perubahan secara signifikan. Tahap selanjutnya data dari proses sayatan tersebut kemudian dilakukanlah pemodelan menggunakan software mag2dc untuk mengetahui sebaran mineral logam dapa daerah tersebut. Berdasarkan data yang telah diolah pada daerah Kertajadi, Cidaun, Kabupaten Cianjur, Jawa Barat dengan koordinat 698283 easting - 757162 easting dan 9180169 northing - 9171050 northing memiliki rentang nilai anomali magnetik -5 nT – 145 nT. Sedangkan nilai anomali magnetik pada daerah yang telah dilakukan proses sayatan memiliki rentang nilai 84.18 nT - 119.69 nT dengan nilai susptibilitas -0.041000 – 0.050001. Dari rentang nilai suseptibilitas tersebut diduga sebaran mineral yang yang memiliki nilai suseptibilitas positif merupakan bijih besi sedangkan yang bernilai negatif merupakan lempung dan endapan pasir. Dari hasil dari penelitian ini diharapkan data tersebut dapat dijadikan informasi dan referensi bagi masyarakat, peneliti lain dan pengusaha tambang dalam eksplorasi mineral logam. Cidaun is one of the coastal areas of the southern coast located in the district of West Java province Cinajur. One of the advantages of the southern coastal areas of Java is that there are many ferrous metal mineral producer widespread along the coast. Therefore, the exploration was undertaken to map the distribution of metallic minerals in the area Cidaun. In conducting metal mineral exploration required a most effective method is a geophysical exploration using geomagnetic methods. Data processing on geomagnetic method is done by calculating the value of the magnetic anomalies of the total magnetic field has a daily correction of correction and correction IGRF. Then, with the inversion method of data has been obtained serve as a model. The researcher also interpretation of qualitative and quantitative interpretation. Qualitative Interperetasi performed on the data that has been modeled using software surfer 11, when the inputs are very high-value magnetic anomalies adjacent to the value of the magnetic anomalies of low value or change in value of the anomaly occurred significantly later performed quantitative interpretation process. Quantitative interpretation in this study conducted a process of delineation of the incision on the difference in magnetic anomaly change significantly. The next stage of the data are then perform the incision process modeling using software mag2dc to determine the distribution of metallic minerals onshore areas. Based on the data that has been processed in the region Kertajadi, Cidaun, Cianjur, West Java coordinate 698283 easting - 757162 easting and 9180169 northing - 917105 northing and has a value range of magnetic anomaly -5 nT - 145 nT. While the value of magnetic anomalies in the area that has been carried out the process of incisions have a range of values 84.18 nT - 119.69 nT with susptibilitas value -0.041000 - 0.050001. Of the value range susceptibility is suspected distribution of minerals that have a positive susceptibility value is the iron ore which is negative while the clay and sand deposits. From the results of this study are expected data can be made of information and reference for the community, other researchers and mining company in mineral exploration.