Crustal Deformation Studies in the Northern Part of East Java Derived from GPS CORS Data between 2015 and 2018

The tectonic setting of Indonesia is very complex due to its location on the boundaries of several major tectonic plates. The complexity of the tectonics also makes Indonesia prone to natural disasters such as earthquakes, tsunamis, and volcanic eruptions. Crustal deformation caused by the tectonics activities can be monitored using geodetic techniques such as Global Positioning System (GPS) and Interferometry Synthetic Aperture Radar (InSAR). In this research, we analyze the crustal deformation in the northern part of East Java using ten GPS Continuously Operating Reference Stations (CORS) data provided by the Indonesian Geospatial Information Agency from 2015 to 2018. The results showed the horizontal movement toward the southeast for all the stations. The horizontal velocity rates are range between 2.62 cm/yr observed at CPAS site, and 3.173cm/yr observed at CNGA station. For the vertical displacements, all the sites are subject to subsidence with the rates range from-0.021cm/yr to-0.4 cm/yr that we suspect related to the geological settings of the study area. However, we found that the vertical annual time series of CMJT stations in 2015 are not consistent; this is because the antenna type was changed on the day of year (doy) 286 in 2015. On the other hand, the strain analyzes in the study area showed considerable compressional strain in the segment formed by three stations, namely CTBN, CSMP and CSBY which are located near to the Kendeng active fault.