UNVEILING EARTHQUAKE-INDUCED DEFORMATIONS: INSIGHTS FROM KAHRAMANMARAŞ SEISMIC EVENT USING AUSPOS ONLINE GPS PROCESSING SERVICE

Determination of crustal movement through geodetic deformation analysis methods provides a better understanding of the severity of the earthquakes. The widespread use of continuously operating GPS stations allows the deformations caused by earthquakes to be investigated with GPS data. In this study, the movements of Continuously Operating Reference Stations-Türkiye (CORS-Tr) stations affected by the Kahramanmaraş earthquakes (Mw 7.7 and Mw 7.6), which was felt in a wide area, were investigated in detail. It is aimed to detect and analyse co-seismic and absolute deformations due to the Kahramanmaraş earthquakes using AUSPOS-online GPS processing service and Iteratively Weighted Similarity Transformation (IWST). Ten stations were selected from the provinces in the earthquake impact area and their 28-day RINEX data, covering before and after the earthquake, were used. The data were processed using AUSPOS. Geodetic deformation analyses were performed using two epoch measurements of established deformation network via in-house software. In addition, the displacements of the two stations close to the epicentre during the monitoring period were revealed by 28-day GPS coordinate time series. Conclusively, it was observed that final S-transformation-derived absolute deformations and average coordinate-derived co-seismic deformations are highly consistent. The results showed that the largest absolute deformation occurred at the EKZ1 station with 4.68m, that was the closest station to the epicentre of the aftershock (Mw 7.6). The absolute deformation at station MAR1, which is the second near station to the epicentre of the aftershock, is 62.5 cm. All Cors-Tr stations were unstable according to deformation analysis results. In particular, unusual vertical movements observed one day prior to the earthquake at the MAR1 station in Kahramanmaraş may indicate potential pre-seismic deformation signals, highlighting the potential of the proposed method for earthquake-related monitoring.