Comparing spatiotemporal shallow creep and afterslip behavior on the Pütürge segment of the East Anatolian Fault with the 2023 M7.7 Pazarcık rupture

Celeste N. Hofstetter, Seda Özarpacı, & Gareth J. Funning

Published September 8, 2024, SCEC Contribution #13709, 2024 SCEC Annual Meeting Poster #084

Turkey's creeping Pütürge segment of the East Anatolian Fault (EAF) experienced a M6.8 earthquake near Elazig on January 24, 2020. Field observations and coseismic slip modeling from InSAR and GNSS data suggest the rupture failed to reach the surface, and the presence of creep on that segment could have arrested the rupture. Recently, with the Kahramanmaras Earthquake Sequence, the 2023 M7.7 Pazarcık NE section of the rupture deviated from the EAF near the Pütürge segment and terminated on an adjacent fault. We investigate the spatial and temporal creep patterns before and after each event, and compare them to the Pazarcık earthquake rupture, to infer what properties may have influenced the observed rupture behaviors.

Using InSAR and GNSS data, we characterize shallow creep and afterslip on the Pütürge segment for the following three periods: interseismic creep (2014-2020) and shallow afterslip after each earthquake (2020-2023 and 2023-2024). We analyzed over 4,000 Sentinel-1 interferograms using ARIA GUNW standard products and our own processed using the ISCE software. We also generated time series, velocity, and cumulative displacement maps using the Mintpy software. We generated creep profiles for the interseismic creep period and timeseries displacement graphs for the afterslip periods to investigate the changes in slow-slip behavior.

Our results show spatiotemporal variations in the Pütürge segment of the EAF slip behavior between the three periods. The interseismic creep period shows shallow creep up to ~6 mm/yr, with the fastest creep rates near Lake Hazar in the NE. After the 2020 M6.8 Elazig earthquake, we infer shallow afterslip of up to ~12 cm, peaking where the Elazig rupture terminated, and identify afterslip in sections that showed no previous creep. After the 2023 M7.7 Pazarcık earthquake, we estimate up to ~6 cm of shallow afterslip, in sections that previously showed minimal creep, close to the end of the 2023 rupture. We find no discernable post-2023 afterslip near Lake Hazar, which previously had high creep rates and post-2020 afterslip, suggesting most of the stored elastic strain in that area may have been released by the 2020 earthquake. Our future goals include generating elastic dislocation models for the three periods to estimate how the shallow creep and afterslip behavior compares to the 2023 M7.7 Pazarcık coseismic slip.

Key Words
InSAR, creep, afterslip, East Anatolian Fault

Citation
Hofstetter, C. N., Özarpacı, S., & Funning, G. J. (2024, 09). Comparing spatiotemporal shallow creep and afterslip behavior on the Pütürge segment of the East Anatolian Fault with the 2023 M7.7 Pazarcık rupture. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy