GEOLOGICAL HAZARD POTENTIAL ZONE ANALYSIS USING GEOGRAPHIC INFORMATION SYSTEM (GIS) APPROACH BASED ON THE INTEGRATION OF GRAVITY AND GEOSPATIAL METHODS IN HALMAHERA ISLAND

• Main Author: Ufaira Aprina, Patria
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/75135
• Institution: Institut Teknologi Bandung

Halmahera is one of the Island located in eastern part of Indonesian Archipelago within the three active plates, Indo-Australia, the Pacific, and the Eurasia. The subduction mechanism of several plates for instance convergence and collision generates to many active geological structures that have the potential to be a seismic activity source. This study utilizes satellite gravity data from the Global Gravity Model Plus (GGMPlus) to identify the distribution of subsurface geological structures. The implementation of gravity data for subsurface structure interpretation employs various approaches such as Tilt Angle (TA), Second Vertical Derivative (SVD), and Euler Deconvolution. The edge detection is used to sharpen the boundaries of anomalies and delineate the geological structures lateral continuity that are not visible on the surface. The interpretation of these geological structures is corroborated by historical earthquake data, assuming the presence of deformation in the structural zone. Armed with this information, the determination of geological hazard zones is combined using surface structure data from geological sources (GS) and relevant geospatial datasets, such as lineament density (Ld), land use (LU), Peak Ground Acceleration (PGA), slope gradient (Sl), groundwater basin (CAT), precipitation (CH), and vegetation index (NDVI) based on the application of the Geographic Information System (GIS) method. Each thematic map is assigned weights and normalized following the Analytical Hierarchy Process (AHP) approach and integrated using the Weighted Overlay Index (WOI) method. Geological hazard potential is categorized into very high (0.679), high (0.522), moderate (0.364), low (0.207), and very low (0.050). Areas with the highest geological hazard potential are distributed in several locations, including Tobelo, Kau, Biang, Jailolo, Sahu and Toguear, Buli Serani, Dogaga, Kobe, and Sosowomo. Thus, the outcome of this research can be used as a reference for geological hazard zoning using GIS AHP and WOI methods in other regions and can be utilized as a basis for early warning and prediction of geological hazards in the Halmahera