Update Artikelilmiah: 5209

TRI RAMAYANTI

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Abstrak (Bhs. Indonesia)

Pemodelan struktur geologi bawah permukaan telah dilakukan di daerah Somagede Kabupaten Banyumas yang merupakan daerah yang diduga memiliki bidang gelincir tanah longsor. Penelitian ini bertujuan untuk membuat model profil 2½ D dan menginterpretasi struktur geologi bawah per-mukaan berdasarkan anomali medan gravitasi. Data anomali medan geavitasi yang digunakan merupakan data sekunder yang diambil dari satelit GEOSAT dan ERS-1 yang telah terkoreksi FA (free air) yang kemudian dilakukan koreksi bouguer, koreksi medan, dan reduksi ke bidang datar sehingga didapat anomali bouguer lengkap di bidang datar. Pemisahan anomali regional-residual menggunakan metode pengangkatan ke atas. Analisis Spektrum dilakukan untuk mengetahui kedalaman rata-rata anomali regional dan residual yaitu 2,65 km dan 0,6 km. Pemodelan struktur geologi bawah permukaan dilakukan dengan cara interpretasi model bawah permukaan dari suatu penampang Anomali Bouguer residual. Pemodelan 2½ D dilakukan menggunakan software Grav2DC. Nilai densitas yang digunakan yaitu 2,67 gr/cm3. Hasil pemodelan pada lintasan AB tanpa informasi dari analisis spektrum diperoleh error 7,98% dan dengan informasi analisis spektrum diperoleh error 9,20% dengan lapisan-lapisan batuan seperti breksi, andesit, batu pasir lempungan dan batu lempung.

Abtrak (Bhs. Inggris)

The Modeling of sub-surface geological structure had been conducted in Somagede, Banyumas which was an area that supposedly had the landslide slip plane. The aims of the research were to created a profile model of 2½ D and interpreted the sub-surface geological structures based on the anomaly of gravitational field. Gravity field anomaly data used were secondary data that retrieved from GEOSAT and ERS-1 satellites which had been corrected FA (free air) and then the Bouguer correction, terrain correction, and reduction to a horizontal plane were conducted to get a complete Bouguer anomaly in the horizontal plane. The separation of the regional-residual anomalies used lifting to the top method. The Spectrum analysis was conducted to determine the average depth of the regional and residual anomalies, and the results obtained were 2.65 km and 0.6 km. The modeling of subsurface geological structures was conducted by interpreting subsurface models from a cross-section residual Bouguer anomaly. The 2 ½ D modeling software was done by using Grav2DC. Density value used was 2.67 gr/cm3. the 2 ½ D modeling was conducted used software Grav2DC. The density value that used was 2.67 gr/cm3. The results of modeling the trajectory AB was made without any information from spectrum analysis obtained error of 7.98% and with the spectrum analysis of information obtained error 9.20% the rock layers is breccia, andesite,clayey sandstone, and claystone.

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