Analyzes of subsidence in Central and East Lombok districts using time lapse microgravity data periods of August 2016 to April 2018

Research has been conducted which aims to analyze the occurrence of subsidence in Central Lombok and East Lombok Districts. Analysis was carried out on changes in microgravity anomalies that occurred during August 2016 to April 2018. Separation of sources of time lapse microgravity anomalies was carried out by filtering using striping filters from Aina and Cordell. Results filtering produces time lapse microgravity anomalies due to shallow sources of 5 to 31 µGal. By use of the free air anomaly formula, time lapse gravity anomaly value are converted to the value of subsidence and yield value of subsidence about 2.0 to 10 centimeters. During the period of the twice gravity measurements the study area has experienced subsidence, with the highest subsidence occurred in the area of Sakra and Kopang and the lowest subsidence occurring along the coast of Lombok East.