An Attempt to Depict Deformation Under a Young Volcanic Covered Area Using 3D Gravity Data Inversion in Southern Garut, Indonesia
Keywords:
3D inversion, active fault, gravity, Indonesia, southern GarutAbstract
Active faults earthquakes often cause serious damage due to their close distance to the center of human activities. Dozens of shallow low magnitude earthquakes were felt in recent years in southern Garut, West Java – Indonesia. Two of these earthquakes (2016 and 2017) were reported destructive and interpreted as an indication of an active fault. Our preliminary study uses published gravity data to depict the subsurface structure that may correlate to this recent seismic activity. We implement three techniques to separate the regionalresidual anomaly from the Bouguer anomaly, Trend Surface, Butterworth Filtering, and Upward Continuation. The results from the three techniques show a relatively same pattern for the residual anomaly map, a relative N-S trending direction in the southern part of West Java, and corresponds well with the geological information. To further extract subsurface information from this data, 3D inversion modeling is implemented. The density model shows a basin with a NE-SW trending local high observed separating two (western and eastern) subbasins. The local high is co-located with a magmatic intrusive body and a series of young volcanic bodies in the northeastern end of the basin. It indicates a tectonic-magmatic relationship in this area.
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