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Seismic Analysis of the 2023 Earthquake Sequence in Southeast Türkiye: Insights From Mainshocks and Aftershocks

Description: 

Two M_w 7.7 and 7.6 earthquakes struck southeast Türkiye on February 6, 2023. The series of earthquakes resulted in extensive destruction and tens of thousands of fatalities in Türkiye and Syria. Using complimentary source characterization methodologies and local, regional, and teleseismic data, we investigate both mainshocks and aftershocks. While the details of the fault network are resolved by centroid moment tensor inversion for 221 aftershocks (M_w ≥ 3.7), back-projection analysis and finite source inversion for the mainshocks reveal coseismic slip, rupture length, and propagation mode along the main faults. Activating the nearby East Anatolian fault zone (EAFZ), the initial mainshock nucleated on a splay fault which is ∼20 km off from the main fault zone. Along approximately 500 km, it ruptured bilaterally on many previously partially dormant fault segments, first toward the northeast and then to the south-southwest during 117 s. The east-west oriented Sürgü-Misis fault zone (SMFZ) was ruptured by the second mainshock, over ∼115 km within 32 s with a slip of 7 m. The reconstruction of slip in the Bayesian bootstrap-based probabilistic joint inversion scheme exploits the model space and trade-off of extended source parameters for the two mainshocks. Source time functions are retrieved without pre-assumptions, and sub-shear rupture velocities are found. Interestingly, the stress drops retrieved from the extended source model were quite different between the mainshocks, with values of 5 and 11 MPa, respectively. The kinematic rupture is also used to calculate slip-induced stress changes which are compared with spatial aftershock distributions. We retroactively reconstruct rupture details using aftershocks with heterogeneous moment tensors including strike‐slip, normal, and thrust events. This not only sheds new light on the geometry and behavior of large structures along the SMFZ but also maps the geometry of various segments along the main strand of the EAFZ. Our research provides valuable insights into the complex rupture evolution and fresh perspectives on the catastrophic earthquake sequence of 2023.

Session: Illuminating Complex, Multiplet Earthquake Sequences at Kahramanmaras (Turkiye), Herat (Afghanistan), and Beyond - I

Type: Oral

Date: 5/2/2024

Presentation Time: 09:00 AM (local time)

Presenting Author: Pinar

Student Presenter: No

Invited Presentation: 

Authors