Application of Moving Average (MA) and Upward Continuation Methods to Bouguer Gravity Anomaly Data for Fault Analysis of the Earthquake Risk Area of Timor and Flores Islands

Eko Minarto*, Naila Yuni Azhari

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


An interpretation of the subsurface structure of the island of Timor and Flores has been carried out based on an analysis of gravity data. The island of Timor and Flores, which is passed by the Ring of Fire, is one of the areas that have a high seismic level. This is due to subduction zones and fault activity. Therefore, this study aims to qualitatively and semi-quantitatively analyze the existence of faults and their types by utilizing secondary data from free-air gravity anomalies. This data is processed into Complete Bouguer Anomaly (CBA) data by determining the average density of the surface using the Nettleton method. The separation of regional and residual anomalies using the upward continuation method to a height of 700 meters and the moving average method. The results of this residual anomaly are then used as input for fault analysis using the correlation profile of the First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) methods using the Elkins filter. For modelling using the Forward Modelling method on Grav2DC. Based on calculations using the Nettleton method, the average density of the surface is 1.23 gr/cm3. A fault is indicated when the FHD curve is at its minimum or maximum peak and the SVD curve is at the zero lines or close to zero. In this study, 12 slices were suspected to be the position of the fault. The average FHD value at the maximum peak is 0.989 mGal/m, while the minimum peak is 0.00038 mGal/m. The type of fault of each slice is determined from the maximum and minimum SVD value. From the research results, normal faults are in the Ruteng area (from the northwest in Nggalak to the east on Mount Wuas), Ende (from the Wulangmang mountains to the northwest to the southeast), and Kupang, while the ascending fault is in the Ruteng area (from the west sea on Mount Wuas straight to the southeast towards Ruteng), Ende (from Bajawa to the east towards Nangapanda), and Atambua. The results of this interpretation are also strengthened by overlaying the suspected fault with the geological map of the study are a and showing the suitability of the fault position even though the fault location is not the same.

Original languageEnglish
Article number012051
JournalJournal of Physics: Conference Series
Issue number1
Publication statusPublished - 12 Jul 2021
Event1st International Symposium on Physics and Applications, ISPA 2020 - Surabaya, Virtual, Indonesia
Duration: 17 Dec 202018 Dec 2020


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