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Coulomb Stress Variation and Frictional Properties Control Postseismic Fault Slip and Late Aftershocks of the 2022 Zagros Earthquake Sequences: Deductions From Bayesian Inference and Insar Observations

Description: 

On 1 July 2022, a doublet of earthquakes both with magnitudes of Mw 6.0 occurred within two hours in the south-eastern part of the Zagros Mountains near the Persian Gulf in Iran. The earthquakes were relatively shallow and caused significant co- and postseismic surface deformation, which could be measured using ascending and descending InSAR scenes. We used these data to invert the geometry of the co-seismic slip and to simulate postseismic deformation mechanisms of the two mainshocks, repectively. A Bayesian inference approach confirmed that the two mainshocks occurred on two distinct faults with similar strike angles but different dip angles and fault depths. The maximum afterslip is concentrated in the shallow portion of the faults and reached approximately 0.45 m. We distinguish the temporal evolution of kinematic and stress-driven afterslip and infer significant variations in frictional properties, particularly between the Hormoz salt layer and its upper sedimentary cover. Friction is stronger above the salt layer and the relaxation time of the afterslip is shorter there. The model confirms and quantifies the decoupling role of the salt layer during and after earthquakes in the south-eastern foothills of the Zagro Mountains.

Session: Illuminating Complex, Multiplet Earthquake Sequences at Kahramanmaras (Turkiye), Herat (Afghanistan), and Beyond [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Torsten

Student Presenter: No

Invited Presentation: 

Authors