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Temporally-Varying Creep Behavior on the East Anatolian Fault and the End of the 2023 Pazarçik Rupture

Description: 

The 80 km-long Pütürge segment of the East Anatolian fault connects the end of the rupture zone of the February 2023 M7.8 Pazarçik earthquake in the SW to Lake Hazar in the NE. The NW half of the segment ruptured at depth in the January 2020 M6.7 Sivrice earthquake, but less is understood about the behavior of the SW half. Given the lack of a major structural barrier to the continuation of the Pazarçik rupture, we consider the possibility that frictional conditions – specifically a transition from stick-slip to aseismic creep – could explain why that rupture ended where it did.

To assess this hypothesis, we process InSAR data from ascending and descending tracks of the Sentinel-1 satellites that cover the Pütürge segment, from three time periods – before, between and after the two earthquakes – using the ISCE and MintPy software. We take short, fault-perpendicular profiles through the velocities and time series we produce to investigate possible creep behavior. We find that: 1) the Pütürge segment was creeping in the period 2014-2020, before the Sivrice earthquake, at rates that peak at ~6 mm/yr at its NE end, and decrease along-strike to effectively zero at its SW end; 2) the post-Sivrice earthquake deformation includes ~10 cm of surface creep between February and July 2020 along the Sivrice rupture zone, followed by a M~5.8 creep event on the fault immediately to the SW of that zone; and 3) the post-Pazarçik earthquake deformation (~10 cm of surface creep in 8 months) is concentrated along the SW-most section of the Pütürge segment, in the zone where there had been little creep before or after the Sivrice earthquake. This continuous and complex shallow creep along the Pütürge segment suggests that creep did play a role in ending the Pazarçik rupture, and also that the limited postseismic creep seen after that event is a result of the release of the majority of the stored elastic strain along the segment after the Sivrice earthquake.

Session: Characteristics and Mechanics of Fault Zone Rupture Processes, from Micro to Macro Scales - I

Type: Oral

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Gareth

Student Presenter: No

Invited Presentation: 

Authors