Analysis of vertical seismic deformation of the 2018 Palu earthquake using Global Navigation Satellite System (GNSS) data

Abstract

Abstract The vertical seismic deformation of the Palu earthquake magnitude of 7.4 on the Richter Scale, which occurred on September 28, 2018, has been analyzed using InaCORS (Indonesian Continuously Operating Reference Stations) stations. The stations used are CBAL, PALP, CTOL, CMLI, CPAL, and CBIT. The analysis was conducted using GAMIT, GLBOK, and GMT software. The analysis focused on the period of 100 days, starting from August 6, 2018 (DoY 218) to November 28, 2018 (DoY 318), encompassing the preseismic, coseismic, and post-seismic phases. During the preseismic phase (DoY 218-270), the InaCORS stations experienced a slight deformation ranging from -10.9353 mm to 6.5525 mm. Tectonic manifestations influenced the direction of movement in Sulawesi. The deformation significantly increased in the coseismic phase (DoY 271-272). The InaCORS stations experienced deformations ranging from -169.8 mm to 8.755 mm, which differed in the direction from the preseismic phase. The stations in the northern region predominantly moved towards the north, while those in the southern region moved towards the south. During the post-seismic phase (DoY 273-318), the movement of the InaCORS stations followed the direction of deformation observed in the coseismic phase. However, the displacement was relatively smaller, ranging from 11.5909 mm to 17.23733 mm.