STUDY OF CALCULATION OF TERRAIN CORRECTION USING SQUARE PATTERN AND SLOPED TRIANGLE METHOD IN KARANGSAMBUNG AREA

• Main Author: Abdus Salam, Rafif
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/42142
• Institution: Institut Teknologi Bandung

One way to estimate terrain correction is by using Hammer chart method. Conventional assessments are carried out by laying out transparent paper containing the Hammer chart on topographic maps, then estimating the average elevation for each compartment. But this procedure has disadvantages, the number of compartments are too small for area with many topographic variations, and there is a subjectivity from the observer in averaging the compartment’s height. To calculate the terrain correction maximally, a high accuracy measurement is needed. In this research, the author tries to calculate terrain correction using the square pattern and sloped triangle method. This method divides the area around the measurement point into a zone containing a square-shaped and triangle compartment. The program tested by using synthetic data to see the effect of rock bodies on terrain correction. The program was applied to Karangsambung to see the topographic influence around Karangsambung on terrain correction. The program is then applied to gravity data, and the results are compared with calculations using the Hammer chart. Based on the synthetic data test, it was found that the value of terrain correction from a rock body measuring 10 x 10 km with a height difference of 1000 m from the station no longer significantly affects at the distance of 20 km. The topography around Karangsambung in the form of South Seraju Ranges with altitude of 1000 m at distance of 20 – 30 km gives effect of 0.05 mGal on terrain correction, while the Quaternary Volcano with an altitude of 3000 m at distance of 30 – 40 km gives effect of 0.1 mGal. The results of applying program at the gravity data show that the use of the square pattern method is able to correct errors from Hammer chart up to 3 mGal. The difference between the calculation of the two methods is getting bigger in the station located at slope area. It happens because estimation of the height difference in slope area is more difficult