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Group B, Poster #058, Tectonic Geodesy

Did creep stop the 2023 Mw7.8 Pazarcık earthquake rupture?

Celeste N. Hofstetter, Seda Özarpacı, & Gareth J. Funning
Poster Image: 

Poster Presentation

2023 SCEC Annual Meeting, Poster #058, SCEC Contribution #13219 VIEW PDF
The February 6, 2023 Kahramanmaras Earthquake Sequence initiated with a Mw7.0 earthquake on the Narlı fault, followed immediately by the Mw7.8 Pazarcık earthquake on the East Anatolian Fault (EAF), and the Mw7.5 Elbistan earthquake on the Çardak fault about nine hours later. The Mw7.8 Pazarcık earthquake ruptured over 300 km of the EAF and is the largest event on that fault since at least the 18th Century. Few significant earthquakes have occurred on the EAF since 1800; however, a Mw6.8 event in 2020, the Sivrice earthquake, ruptured nearly 40 km of the EAF, near Elazığ, ~40 km NE of the NE end of the Pazarcık rupture. Estimates of slip from the 2020 and 2023 earthquake events suggest an unr...uptured segment (known as the Pütürge segment) of the EAF between the Pazarcık and Sivrice ruptures. Published research on the 2020 event suggests it may have been arrested by creep on the EAF, possibly from velocity-strengthening friction and/or reduced interseismic strain accumulation. Could creep have arrested the 2023 rupture propagation as well?

To answer this question, we analyze InSAR data over the Pütürge segment of the EAF. We use over 5000 ARIA standard product interferograms from two ascending and descending tracks of the Sentinel-1 satellites and the MintPy software to produce InSAR time series and velocity maps. Data from 2014-2020, before the Sivrice earthquake, show an abrupt line-of-sight velocity change localized from the SW end of the 2020 rupture, extending along the EAF trace to within ~10 km of the end of the 2023 rupture. This feature is suggestive of creep on the Pütürge segment at rates of 5-8 mm/yr. The juxtaposition of this creeping zone and the northeastern extent of modeled coseismic slip of the 2023 event, constrained by SAR image offset data, suggests that the arrest of the 2023 rupture by creep is plausible and warrants further investigation.