Quality Analysis of the Geodetic Control Networks for Purposes of Geodynamics Study of Sangihe Island

The Sangihe Islands in Sulawesi Utara are located at three tectonic plates, Collins area, therefore the Sangihe Islands are one of the natural disaster-prone areas, especially earthquakes. To reduce the effect of disasters, studies related to geodynamics are carried out, one of the studies uses the multi-epoch GPS survey method. Three points Sangihe Geodynamic monitoring network has been defined since 2014, which are SGH1, SGH2 and SGH3. In this study, the quality of the network has been analyzed and used for the purpose of geodynamics study based on 2014 and 2015 epochs GNSS data measurement. The results show that the accuracy and reliability of the network based on A-optimality, E-optimality, S-optimality, I-optimality and D-optimality criteria meet the minimum criteria, therefore the network can be used for geodynamics studies. Comparing the 2015 and 2014 coordinates shows that the movement of the SHG1 horizontally is 15 mm/year to southeast and increased vertically 9 mm/year, the SGH2 deformed horizontally 200 mm/year to southeast and decreased vertically 55 mm/year and the SGH3 deformed horizontally 3.6 mm/year with same direction to the others and decreased vertically 14 mm/year.