Solak, Halil Ibrahim; Tiryakioglu, Ibrahim; Gezgin, Cemil; Aladogan, Kayhan; Yalvaç, Sefa; Aktug, Bahadir; Yigit, Cemal Ozer; Dönmez, Ergin; Demirelli, Ertugrul; Eyübagil, Eda Esma

Highlights What are the main findings? What are the implications of the main findings?Highlights What are the main findings? What are the implications of the main findings?Abstract Postseismic deformation provides fundamental insights into earthquake-cycle processes, lithospheric rheology, and stress redistribution following large earthquakes. Although the 2020 Mw 7.0 Samos earthquake has been extensively investigated in terms of coseismic deformation and early postseismic behavior, the long-term evolution of deformation following the event remains poorly constrained. This study characterizes the long-term spatiotemporal evolution of postseismic deformation associated with the 2020 Mw 7.0 Samos earthquake using combined campaign and continuous GNSS observations. A total of 18 GNSS stations were analyzed over an approximately 4.5-year period following the earthquake. Pre-earthquake GNSS velocities were incorporated as prior constraints, while postseismic deformation was modeled using linear, logarithmic, exponential, and combined logarithmic-exponential functions. The preferred model for each station component was identified using the corrected Akaike Information Criterion (AICc), and model-selection robustness was evaluated through 1000 Monte Carlo observation-perturbation simulations. The results reveal a spatially heterogeneous postseismic deformation field with station-dependent temporal behavior. Among the nonlinear solutions passing the Monte Carlo and goodness-of-fit criteria, the seven single-process LOG and EXP solutions yielded characteristic relaxation times ranging from 182.6 to 730.5 days, with a median of 438.3 days. The two LOGEXP solutions additionally contained a logarithmic timescale of 109.6 days and exponential timescales of 292.2-438.3 days. These findings demonstrate that campaign GNSS observations, when integrated with continuous GNSS data and an objective statistical framework, can provide meaningful constraints on the long-term evolution of postseismic deformation despite sparse temporal sampling. More broadly, the results emphasize the strongly time-dependent nature of postseismic deformation and the critical role of observation timing in capturing its spatiotemporal evolution.

Gezgin, Cemil; Solak, Halil Ibrahim; Tiryakioğlu, İbrahim; Ozener, Haluk; Aktug, Bahadir; Yalvac, Sefa; Eyübagil, Eda Esma; Yigit, Cemal Ozer; Demirelli, Ertuğrul; Çakanşimşek, Ece Bengünaz

Solak, H., Tiryakioğlu, İ., Yalvaç, S., Yiğit, C.Ö., Aktuğ, B., Özener, H., Dönmez, E., Demirelli, E., Eyübagil, E.E., Çakanşimşek, E.B., Gezgin, C., Şahiner, F., 2024. 30 Ekim 2020 Mw:6.9 Sisam Depremi Sonrası İzmir ve Çevresinde Postsismik Deformasyonların İzlenmesi, Afyon Kocatepe Üniversitesi, Fen ve Mühendislik Bilimleri Dergisi, 24 (6): 1442-1455. https://doi.org/10.35414/akufemubid.1465489 Yukarıda künye bilgileri verilen makale için yazar tarafından düzeltme talebinde bulunulmuştur. Makalenin kaynakça bölümünde yer alan “Çırmık, A., Pamukçu, O. and Gönenç, T., 2017. The Stress/Strain Analysis of Kinematic Structure at Gülbahce Fault and Uzunkuyu Intrusive (İzmir, Turkey). Pure and Applied Geophysics, 174, 1425- 1440. https://doi.org/10.1007/s00024-017-1474-5” kaynağının sehven hatalı olarak yazıldığı makale yayınından sonra tespit edilmiştir. Yazarın yazılı talebine istinaden ilgili kaynak aşağıda belirtilen şekliyle düzeltilmiştir. Okuyucuların ve kullanıcıların bilgisine sunarız.

Gezgin, Cemil; Solak, Halil Ibrahim; Tiryakioğlu, İbrahim; Ozener, Haluk; Aktug, Bahadir; Yalvac, Sefa; Eyübagil, Eda Esma; Yigit, Cemal Ozer; Demirelli, Ertuğrul; Çakanşimşek, Ece Bengünaz

A devastating (Mw: 6.9) earthquake occurred in the north of Samos island on October 30, 2020. This earthquake caused loss of life and property in Izmir city center and some districts. After the earthquake, studies conducted in Izmir and its south showed that there was a horizontal displacement of 4-14 cm in Izmir and its south, the largest of which was in Seferihisar. In this region, there are many active faults with the potential to produce earthquakes between Mw:6.1 and Mw:6.9. A 27-site GNSS network has been established to monitor the postseismic deformation in this region since an earthquake can affect the earthquakes that may be caused by other surrounding faults. 4 GNSS campaign measurements were conducted over 6-month periods between 2020 and 2022 in this network. Eurasian fixed velocities of all sites were obtained using GNSS data. The results obtained show that the differences between both the current velocities and the pre-earthquake velocities in the network have reached 6 mm, and accordingly, the postseismic deformation continues in the region.