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.

I. Introduction

Sangihe Islands are located in North Sulawesi and adjacent to the Philippines and lies at three tectonic plates collins area, namely Philippine sea plate, Carolin plate and Pacific plate. In addition, The Sangihe Islands area is also located at a trans-Pacific volcano area of the Hawaii Region, Japan, Philippines and ends in Maluku Region. This causes the Sangihe Islands are prone to natural disasters, including earthquake disasters. Earthquakes with the strength above 4.5 SR occur every year in the Sangihe Islands. In connection with these conditions, it is necessary to monitor the geodynamics of the Sangihe islands as the basis for disaster mitigation to reduce the impact of the disasters.