Monitoring of Crustal Movements in the Eastern Gulf of Gokova with GNSS Measurements

As a result of the interaction between the Anatolian Plate and the African Plate to the south, and the Aegean microplate to the west, a complex extensional regime has developed across Western Anatolia. This dynamic tectonic framework causes significant crustal deformation and temporal strain accumulation, particularly along the active Fethiye–Burdur and Gökova fault zones. The Aegean region is considered one of the most seismically active areas worldwide. The Mw 6.7 earthquake that occurred within the Gulf of Gökova on 21 July 2017 represents one of the most recent destructive earthquakes in the region. Despite the pronounced seismic activity in this area, no active fault zones are mapped in this section of the Turkish Active Fault Map. The absence of mapped active structures has highlighted the necessity of detailed investigations into the region’s present-day tectonic deformation characteristics. Within the scope of this study, the aim is to determine crustal deformation and temporal strain accumulation based on Global Navigation Satellite System (GNSS) observations. For this purpose, the region has been monitored since 2021 through campaign-based GNSS measurements and data obtained from continuously operating GNSS stations.

In the study, GNSS data has been collected from 6 CORS-TR (Turkey National Permanent GNSS Network- Active) stations, 7 Turkey National Fundamental GNSS Network (TNFGN) sites, and 16 campaign GNSS sites. Four GNSS campaign measurements were carried out between 2021 and 2024 .The GNSS data were processed to generate coordinate time series and estimate station velocities using with Bernese GNSS Software version 5.4. Based on these results, a statistically significant velocity field was identified across the region, with horizontal southwest-directed velocities ranging from a maximum of 41.67 ± 1.76 mm/yr to a minimum of 22.05 ± 2.95 mm/yr. Also, temporal strain accumulation in the region was computed using a finite element method . The results indicate that the eastern and western parts of the region are characterized by different strain fields, and that the amount of strain has increased and expanded spatially over the observations.

This work is supported by TUBITAK CAYDAG Project Number 121Y300