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Sabang Submarine Volcano Aceh, Indonesia: Review of Some Trace and Rare Earth Elements Abundances Produced by Seafloor Fumarole Activities kurnio, Hananto; Syafri, Ildrem; Sudradjat, Adjat; Rosana, Mega Fatimah
Indonesian Journal on Geoscience Vol 3, No 3 (2016)
Publisher : Geological Agency

DOI:10.17014/ijog.3.3.173-182Geochemical analyses of selected coastal and seafloor samples from Sabang Area revealed abundances of trace and rare earth elements. The selected samples of element abundances were mostly taken from seafloor in the vicinities of active fumaroles either by grab sampler operated from survey boat above fumarole point or by diver directly took the samples on the seafloor especially at Serui - Sabang Bay. Results show that samples closed to seafloor fumaroles demonstrate plenty of trace and rare earth elements. The trace and rare earth elements mean values (n=10) are: Nb (4.33 ppm), La (16.52 ppm), Ce (38.82 ppm), Nd (19.15 ppm), Ce (38.82 ppm), Pr (4.907 ppm), Nd (19.15 ppm), Sm (4.04 ppm), Gd (3.95 ppm), Dy (3.38 ppm), Th (6.432 ppm), and U (4.335 ppm). Negatively, statistical correlations between Fe, Zn, and Ni as the main sulphide elements with sulphur is interpreted that sulphide minerals do not form in the Sabang Sea. Sea water influence in the mineralization process was shown by the good correlations between Fe, Zn, Pb, Ni, and Ba.

Geomorphic Analysis in Determining Tectonic Activity Affected by Sumatra Fault in Liwa Region and Its Surrounding Area, Lampung, Indonesia Yudhicara, Yudhicara; Muslim, Dicky; Sudradjat, Adjat
Indonesian Journal on Geoscience Vol 4, No 3 (2017)
Publisher : Geological Agency

DOI: 10.17014/ijog.4.3.193-208The study discusses about characteristics of Sumatra Fault and its tectonic activity in Liwa and the adjacent area. The research uses quantitative methods of verification hypothetical deduction, which starts from the general approach, then it pursues into more specialized and focused ones. While the research work includes field measurements, remote sensing with GIS, and geomorphologic analysis using morphometry, such as: sinousity of mountain front (Smf), percentage of facets, ratio of the width and height of the valley (Vf), bifurcation ratios of the river (Rb), drainage density (Dd), shape of the watershed basin area (Bs), hypsometric curves (HI), and gradient index of stream length (SL). Basically, two blocks separated by the Sumatra Fault do not have a significant difference in tectonic activity, but the tectonic activity change can be seen when the studied area is divided into three blocks (northwest, middle, and southeast), then the change in each part can clearly be seen. Apparently, the tectonic activity in the studied area starts from the southeast continues toward the northwest. It is proved by this research, that geomorphological parameters which are associated with mountain fronts and watershed systems demonstrate the value of the activity increases towards the northwest. Hypsometric curves and a river analysis show that the tectonic activity in the northwest is relatively in a young stage, while towards the southeast it is getting in a mature stage.

Sedimentation Process of Rambatan Formation in Larangan Brebes, North Serayu Range, Central Java Astuti, Bernadeta Subandini; Isnaniawardhani, Vijaya; Abdurrokhim, Abdurrokhim; Sudradjat, Adjat
Indonesian Journal on Geoscience Vol 6, No 2 (2019)
Publisher : Geological Agency

DOI:10.17014/ijog.6.2.141-151Rambatan Formation in the western part of North Serayu Basin, Brebes, Central Java, comprises generally flysch facies of turbidite sediments deposited in a deep marine environment. This formation is equivalent to Merawu Formation found in the eastern part of the basin and deposited in the environment of tidal flat to subtidal. The turbidite sediments were highly controlled by a rapid downward movement taking place continuously during Early to Late Miocene. The variation of the depositional environment has been the object of this research which aims to understand the sedimentation process of Rambatan Formation in this type locality with a modern turbidite approach. Rambatan Formation was deposited in N13-N19, as a deep marine sediment channel, turbidite, and deep marine tidal zone. The sedimentation was affected by gravity flow and contourite. The sediments on N13-N14 were marked by turbidite sediments until Middle N17. The sediment supply increased on Middle N17, as a sediment filler on a channel marked by contourite mud layer (muddy slump) and debris flow, with sources from the north. The increase of sediment supply was followed by an environmental transformation from a deep marine channel into deep marine tidal area. In N19, the sediments were redeposited as turbidite sediment, starting with debris flow in Middle N18.

Sabang Submarine Volcano Aceh, Indonesia: Review of Some Trace and Rare Earth Elements Abundances Produced by Seafloor Fumarole Activities kurnio, Hananto; Syafri, Ildrem; Sudradjat, Adjat; Rosana, Mega Fatimah
Indonesian Journal on Geoscience Vol 3, No 3 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.3.173-182

DOI:10.17014/ijog.3.3.173-182Geochemical analyses of selected coastal and seafloor samples from Sabang Area revealed abundances of trace and rare earth elements. The selected samples of element abundances were mostly taken from seafloor in the vicinities of active fumaroles either by grab sampler operated from survey boat above fumarole point or by diver directly took the samples on the seafloor especially at Serui - Sabang Bay. Results show that samples closed to seafloor fumaroles demonstrate plenty of trace and rare earth elements. The trace and rare earth elements mean values (n=10) are: Nb (4.33 ppm), La (16.52 ppm), Ce (38.82 ppm), Nd (19.15 ppm), Ce (38.82 ppm), Pr (4.907 ppm), Nd (19.15 ppm), Sm (4.04 ppm), Gd (3.95 ppm), Dy (3.38 ppm), Th (6.432 ppm), and U (4.335 ppm). Negatively, statistical correlations between Fe, Zn, and Ni as the main sulphide elements with sulphur is interpreted that sulphide minerals do not form in the Sabang Sea. Sea water influence in the mineralization process was shown by the good correlations between Fe, Zn, Pb, Ni, and Ba.

Geomorphic Analysis in Determining Tectonic Activity Affected by Sumatra Fault in Liwa Region and Its Surrounding Area, Lampung, Indonesia Yudhicara, Yudhicara; Muslim, Dicky; Sudradjat, Adjat
Indonesian Journal on Geoscience Vol 4, No 3 (2017)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.4.3.193-208

DOI: 10.17014/ijog.4.3.193-208The study discusses about characteristics of Sumatra Fault and its tectonic activity in Liwa and the adjacent area. The research uses quantitative methods of verification hypothetical deduction, which starts from the general approach, then it pursues into more specialized and focused ones. While the research work includes field measurements, remote sensing with GIS, and geomorphologic analysis using morphometry, such as: sinousity of mountain front (Smf), percentage of facets, ratio of the width and height of the valley (Vf), bifurcation ratios of the river (Rb), drainage density (Dd), shape of the watershed basin area (Bs), hypsometric curves (HI), and gradient index of stream length (SL). Basically, two blocks separated by the Sumatra Fault do not have a significant difference in tectonic activity, but the tectonic activity change can be seen when the studied area is divided into three blocks (northwest, middle, and southeast), then the change in each part can clearly be seen. Apparently, the tectonic activity in the studied area starts from the southeast continues toward the northwest. It is proved by this research, that geomorphological parameters which are associated with mountain fronts and watershed systems demonstrate the value of the activity increases towards the northwest. Hypsometric curves and a river analysis show that the tectonic activity in the northwest is relatively in a young stage, while towards the southeast it is getting in a mature stage.

Sedimentation Process of Rambatan Formation in Larangan Brebes, North Serayu Range, Central Java Astuti, Bernadeta Subandini; Isnaniawardhani, Vijaya; Abdurrokhim, Abdurrokhim; Sudradjat, Adjat
Indonesian Journal on Geoscience Vol 6, No 2 (2019)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.6.2.141-151

DOI:10.17014/ijog.6.2.141-151Rambatan Formation in the western part of North Serayu Basin, Brebes, Central Java, comprises generally flysch facies of turbidite sediments deposited in a deep marine environment. This formation is equivalent to Merawu Formation found in the eastern part of the basin and deposited in the environment of tidal flat to subtidal. The turbidite sediments were highly controlled by a rapid downward movement taking place continuously during Early to Late Miocene. The variation of the depositional environment has been the object of this research which aims to understand the sedimentation process of Rambatan Formation in this type locality with a modern turbidite approach. Rambatan Formation was deposited in N13-N19, as a deep marine sediment channel, turbidite, and deep marine tidal zone. The sedimentation was affected by gravity flow and contourite. The sediments on N13-N14 were marked by turbidite sediments until Middle N17. The sediment supply increased on Middle N17, as a sediment filler on a channel marked by contourite mud layer (muddy slump) and debris flow, with sources from the north. The increase of sediment supply was followed by an environmental transformation from a deep marine channel into deep marine tidal area. In N19, the sediments were redeposited as turbidite sediment, starting with debris flow in Middle N18.

Evolusi Cekungan Serayu pada Paleogen hingga Neogen Awal Syaiful Bachri; Febri Hirnawan; Adjat Sudradjat; Ildrem Syafri; Djajang Sukarna
Indonesian Journal of Applied Sciences Vol 1, No 3 (2011)
Publisher : Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/ijas.v1i3.1877

On the basis of paleogeographic study, it is revealed that during Paleogene, or exactly during Middle Eocene – Oligocene times, the southern part of the study area was occupied by the Bogor Trough Low, or Bobotsari Low in the Purbalingga area. The lows were bounded by the Southern Serayu Range high in the south. During that time, the South Serayu Range high , including the active volcanoes on it , was still above the sea level, and therefore the Serayu Basin formed a back arc basin. During the Neogene time the volcanic belt moved northwards to the north of the Bogor Through. The peak of volcanism occurred during Late Miocene – the lower part of Early Pliocene, which is indicated by formation of the Kumbang volcanic rocks. Meanwhile, the South Serayu Range has been submerged by transgression event causing the Serayu Basin turned to be fore-arc basin. The method used in this research is probabilistic analysis involving XRD variable, i.e. Q/(Q+F) or quartz per quartz and feldspar, and petrographic analysis variable, i.e. amount of constituents of volcanic origin or total volcanic rock fragments and volcanic glass (Rv+Gv). The result of probabilistic analysis using the variables as mentioned previously suggests that since the formation of the Worawari Formation (Middle Eocene – Oligocene) to the formation of the Penyatan Formation (Late Miocene – lower part of the Early Pliocene) tectonic activity increased, triggering increasing volcanic activity. ****Berdasarkan studi paleogeografi diketahui bahwa selama Paleogen, atau tepatnya pada waktu Eosen Tengah – Oligosen, bagian selatan daerah penelitian ditempati oleh rendahan Palung Bogor, atau rendahan Bobotsari di daerah Purbalingga, sementara rendahan tersebut berbatasan langsung dengan tinggian Pegunungan Serayu Selatan. Pada waktu itu Pegunungan Serayu Selatan beserta gunungapi – gunungapi yang aktif masih berada di atas muka air laut, sehingga Cekungan Serayu merupakan cekungan busur – belakang. Pada waktu Neogen, terjadi pergeseran lajur gunungapi ke sebelah utara Palung Bogor. Puncak kegiatan vulkanisme terjadi pada Miosen Akhir – bagian bawah Pliosen Awal, yang ditandai oleh pembentukan Batuan Gunungapi Kumbang. Sementara itu, Pegunungan Serayu Selatan sudah tenggelam oleh peristiwa genang-laut yang menyebabkan Cekungan Serayu berubah menjadi cekungan busur muka. Metode yang dipakai dalam penelitian ini adalah analisis probabilistik yang melibatkan variabel defraksi sinar-X , yaitu Q/(Q+F) atau kuarsa per kuarsa dan feldspar, dan variabel dari analisis petrografi, yaitu jumlah penyusun asal volkanik atau total fragmen batuan volkanik dan gelas volkanik (Rv+Gv). Hasil analisis probabilistik dengan variabel-variabel tersebut di atas menunjukkan bahwa sejak pembentukan Formasi Worawari (Eosen Tengah – Oligosen) hingga Formasi Penyatan (Miosen Akhir – bagian bawah Pliosen Awal) menunjukkan peningkatan kegiatan tektonik yang disertai peningkatan kegiatan gunungapi.

KRITERIA KERUSAKAN AKIBAT PELEDAKAN PADA PEMBUATAN TEROWONGAN CIURUG, TAMBANG EMAS PONGKOR, KABUPATEN BOGOR, PROVINSI JAWA BARAT Awang Suwandhi; Mega Fatimah Rosana; Adjat Sudradjat; Ridho Kresna Wattimena
Buletin Sumber Daya Geologi Vol. 12 No. 2 (2017): Buletin Sumber Daya Geologi
Publisher : Pusat Sumber Daya Mineral Batubara dan Panas Bumi

Untuk mencapai urat (vein) bijih di lokasi Central pada Level 500 mdpl, Ciurug, dibuat terowongan baru yang dinamakan RU4C-L500 dengan menerapkan teknik peledakan. Terowongan tersebut dirancang berukuran lebar 4 m, tinggi 4 m dan panjang 100 m sampai ke cross-cut menuju urat bijih. Penelitian dilakukan dengan tujuan untuk mendapatkan kriteria kerusakan terowongan yang diakibatkan oleh induksi getaran peledakan yang berpotensi menghasilkan overbreak, sehingga ukuran terowongan menjadi lebih lebar dari rencana semula. Pendekatan Blast Damage Index (BDI) digunakan sebagai metode untuk memperoleh tingkat kerusakan terowongan tersebut. Terowongan menerobos batuan andesit vulkanik yang berdasarkan hasil pengujian memiliki kecepatan rambat gelombang seismik 4157 m/det, densitas 2,37 g/cc dan kuat tarik 8,10 MPa. Batuan tersebut tergolong batuan berkekuatan sedang hingga keras dengan nilai Rock Mass Rating (RMR) antara 58,3 sampai 69,5. Data getaran peledakan diukur dengan menggunakan geofon pada jarak yang aman dari titik ledakan dan menghasilkan Peak Vector Sum (PVS) berkisar antara 2 mm/s sampai 120 mm/s. Hasil pengolahan data getaran menunjukkan, bahwa nilai BDI sebesar 2 yang mengidentifikasi adanya ambrukan terowongan karena induksi getaran peledakan terjadi pada jarak kurang dari 3 m dari titik ledakan. Besar getaran peledakan yang mengambrukan batuan andesit vulkanik tersebut mencapai PVS 1170 mm/s. Pada jarak antara 3,0 m sampai 10 m tidak terjadi kerusakan terowongan yang parah dan dapat direhabilitasi. Kondisi tersebut diidentifikasi oleh nilai BDI 0,5 sampai 1. Kemudian pada jarak di atas 10 m induksi getaran peledakan tidak lagi berpengaruh terhadap kerusakan atau kestabilan dinding terowongan.

THE IMPLEMENTATION OF NAÏVE BAYES AND SUPPORT VECTOR MACHINE (SVM) ALGORITHM , IN DETERMINING ACHIEVING STUDENTS IN SMP NEGERI 8 CIMAHI Adhitiawarman, Adhitiawarman; Hartanto, Dwi; Sudradjat, Adjat; Sari, Retno
JITK (Jurnal Ilmu Pengetahuan dan Teknologi Komputer) Vol 7 No 1 (2021): JITK Issue August 2021
Publisher : LPPM Nusa Mandiri

Classification is a technique in data mining to classify data based on data attachment to sample data. In this study, we conducted a comparison of classification techniques to classify students who excel in the dataset of SMP Negeri 8 CIMAHI. Comparison of classification techniques is carried out to see which models in the classification technique are most effective for classifying targets in the dataset of SMP Negeri 8 CIMAHI. The classification technique used is the Support Vector Machine and Naïve Bayes. The classification process begins with preprocessing data to remove missing values and select features in the dataset. After testing, it was found that the accurate classification results were obtained by the Support Vector Machine model with an accuracy value of 93%. Whereas for the Naïve Bayes model the accuracy results are 88%. for this case the Support Vector Machine was chosen as the model that has the best accuracy and the resulting visualization results are clearer to classify outstanding students in the dataset of SMP Negeri 8 CIMAHI.

Implementasi Metode Kanban pada Rancangan Sistem Informasi HelpDesk Pada Kantor Imigrasi Berbasis Website Lubis, Baginda Oloan; Carolina, Irmawati; Supriyatna, Adi; Sudradjat, Adjat; Destiana, Henny; Komarudin, Rachman
Jurnal Infortech Vol 5, No 2 (2023): Desember 2023
Publisher : Universitas Bina Sarana Informatika

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31294/infortech.v5i2.17163

Pada kantor imigrasi, terdapat berbagai urusan seperti pembuatan paspor biasa, penarikan, pencabutan, pembatalan, dan penggantian paspor biasa, pembuatan paspor bagi jamaah calon haji, pembuatan surat perjalanan laksana paspor, rekomendasi visa bekerja dan berlibur (work and holiday visa), serta biaya keimigrasian bagi WNI, dan lain sebagainya. Namun, dalam proses-proses tersebut, seringkali masyarakat mengajukan komplain yang belum tertangani dengan baik. Pencatatan dan penanganan komplain masih belum terorganisir dengan baik, sehingga data komplain sulit ditemukan ketika dibutuhkan. Oleh karena itu, berdasarkan penelitian, penulis berkeinginan untuk mengembangkan sistem informasi berbasis website yang dapat menangani komplain di kantor imigrasi. Sistem ini diharapkan dapat menghasilkan data komplain yang terintegrasi, efektif, dan efisien. Selain itu, sistem ini akan memfasilitasi pengakomodasian dan perekaman data komplain, sehingga penanganan dapat selesai dengan cepat. Peneliti juga berharap agar data komplain diarsipkan dengan baik, sehingga mudah ditemukan ketika dibutuhkan. Yang terakhir, laporan komplain akan dibuat sebagai acuan perbaikan prosedur di kantor imigrasi. Metode kanban digunakan dalam pengembangan sistem informasi ini. Dengan memanfaatkan metode kanban, pengelolaan komplain di kantor imigrasi dapat ditingkatkan, menciptakan sistem yang terintegrasi, efisien, dan efektif dalam menangani komplain masyarakat, serta mengelola data komplain dengan baik.

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