Crustal Deformation Changes due to M4 Class Earthquake Near Kendeng Thrust Detected by Geodetic Data

One of the intraplate faults in Java Island, which may significantly produce a future earthquake, is the Kendeng thrust. The shallow earthquake with magnitude 4.3 struck Madiun, East Java on June 25, 2015, causing damage in the region. In this study, we analyze the crustal deformation response based on Global Positioning System (GPS) observation data. A total of 11 GPS stations provided by BIG scattered near the Kendeng thrust. Observation data was processed based on the least squares computation method using GAMIT/GLOBK software. We obtained the daily solution of each GPS station and calculated velocity changes before and after the earthquake. The result shows that there was a change in the deformation rate before and after the earthquake. The deformation features consist of displacement in horizontal velocity from southeast to east, while vertical trend varies from subsidence (CSEM, CMAG, CNGA, CLMG, CBLR), uplift (CJPR) and changes from subsidence to uplift (CMJT, CPWD, CSBY, CSLO, CTBN).