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Rupture Process of the February 2023 Mw 7.8 Earthquake Sequence in South-Central Türkiye and Northwestern Syria From Teleseismic P-Wave Data

On February 6, 2023, two destructive earthquakes of Mw 7.8 and 7.6 struck the south-central part of Türkiye. The first event (E1) started on an off-fault branch near the East Anatolian Fault (EAF) and the second one (E2) occurred on the east-west trending Sürgü fault ~9 hours later. We use back-projection (BP) and finite fault inversion (FFI) with teleseismic P-wave to image the rupture process of these two earthquakes. For the BP, we use Alaskan stations and only target high cross-correlation coefficients (>0.6). The FFI uses 18 and 17 seismic recordings for E1 and E2, respectively, ensuring good azimuth coverage. We define segmented rupture-plane geometries using fault traces derived from satellite radar image pixel offset tracking. We parameterize E1 with 4 fault segments, each with a uniform dip of 89^o, whereas E2 comprises 3 segments dipping 78^o to the north. All segments are discretized into 5 x 5 km² subfaults, on which we solve for slip, rupture onset time, and rise time. In addition, we explore the model space using Bayesian inference to account for the non-uniqueness of the inversion solution.

Both the BP and FFI results indicate bilateral rupture propagation for both earthquakes. The BP results for E1 show that the rupture propagated to the northeast along a fault branch until it reached the EAF, then it continued along EAF to the northeast for up to ~55 s. The rupture to the southwest along the EAF, towards the Hatay province, appears to have been delayed and then terminated at ~80 s. For E2, we observe frequency-dependent BP results due to the directivity effect. The BP captures the rupture to the east and then northeast in a lower frequency range (0.1-0.5 Hz), while it images opposite rupture direction to the west in a higher frequency range (0.5-1 Hz). The FFI result of E1 shows at least three high-slip patches with the maximum slip of up to 8 m. The slip model of E2 shows high slip of above 8 m near the surface of the Sürgü fault, but less slip to the northeast and southwest. Overall, our modeled moment magnitudes of the two events are Mw 7.97 and Mw 7.77, respectively.

Session: February 2023 Mw 7.8 Earthquake Sequence in Turkey [Poster]

Type: Poster

Room: Ballroom

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Cahli Suhendi

Student Presenter: Yes

Additional Authors