Karit Lumban Gaol

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).