Fracture analysis to delineate tectonic evolution: Case study at Ciherang, Bogor-Sukabumi, West Java, Indonesia

Abstract

Indonesia, especially Java island is strongly influenced by tectonic processes and volcanic processes. The phenomenon of fractures in volcanic areas provide a significant contribution to the process of calculating the potential of its groundwater resources. Ciherang area, West Java is located among two quaternary volcanoes, namely Mt. Salak and Mt. Pangrango, composed by volcanic deposits of both volcanoes, and also affected by Pelabuhanratu fault as regional fault. Fracture pattern on Mt. Salak and Mt. Pangrango not only influenced by volcanism only but also influenced by Pelabuhanratu fault with relatively older than the volcanic processes that occur in both the mountain. By using the method of automatic lineament extraction on ASTER GDEM raster image with the resolution of 30m × 30m per pixel, then obtained the lineament of the ridge and valley. Each group has its character itself with influence by volcanic processes, tectonic processes or both of volcanic and tectonic processes. Subwatershed created to divide fracture and to describe tectonic style involved in each subwatershed, due to subwatershed become important parameter to restrict population of lineament. Delineation of fracture pattern based on subwatershed have a difference style of direction for each subwatershed.