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Northern part of Lombok island has a unique geological phenomenon of submarine groundwater discharge. Submarine groundwater discharge needs to be conserved for its sustainability. This study asseses groundwater vulnerability for SGD conservation in the northern part of Lombok Island Indonesia. The assessment was conducted using aquifer vulnerability index methods. Vulnerability index value in the study area is high vulnerability index. This vulnerability index is getting higher toward the coast. The layer is tuffaceous pumice layer with a hydraulic conductivity value of 5 m/day. This layer makes the aquifer in the study area very vulnerable to contamination, especially for pollution involving vertical percolation and infiltration. Protective management is needed to prevent groundwater hazard in the research location due to groundwater pollution and heavy pumping. Anthropogenic activity at the study area should be anticipated because of the high index of aquifer susceptibility at the study area.

We present an interpretation of newly acquired audio-magnetotelluric data to reveal the subsurface geometry of Cimandiri Fault Zone, one of the major active faults in the western part of Java. The line section is 25 km long in a nearly north–south direction across the axes of CFZ with 24 stations of 750–1200 m spacing intervals. The 2D AMT inversion model shows two conductive zones in the southern part that may be associated to the Miocene rocks of the Southern Mountains, and a conductive zone in the northern part that is likely to be associated with Gunung Walat fold-belt. The subsurface structures of the Southern Mountains are dominated by south-dipping thrusts that may uplift the shallow marine sediments. Shallow seismicity occurred around CFZ indicating the activity of these blind thrusts.