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Reconnaissance Geological Observations of the February 06, 2023 Kahramanmaraş, Türkiye Earthquakes

The Kahramanmaraş, Türkiye earthquake sequence occurred on February 6, 2023 along the East Anatolian fault (EAF) system, resulting in widespread damage and casualties. The epicenter of the first event (Mw7.8) was approximately 35 km northwest of the city of Gaziantep along the Narlı fault and generated surface fault rupture of over 300 km along the EAF between Antakya and Karaköse. The second event (Mw7.5) located northwest of the EAF and initiated near the city of Elbistan, rupturing ~142 km of the Çardak-Sürgü faults. Subsequent to the earthquakes, the Geotechnical Extreme Events Reconnaissance (GEER) Association mobilized teams to the affected area to document perishable geological and geotechnical data. The investigation included a regional assessment of the impacts to infrastructure (i.e. bridges, pipelines) as well as documentation of the geological effects (surface fault rupture, liquefaction, lateral spread, landslides). Here we present surface slip measurements collected between the towns of İslahiye and Nurdağı, and near Narlı, Çiğli, Kartal, and Balkar along the Mw7.8 rupture and between the vicinities of Çiftlikkale and Barış along the Mw7.5 rupture. Left-lateral surface displacements along the Mw 7.8 EAF rupture were remarkably consistent, 3 to 4 m, but diminished to the south near Antakya to around 0.5 m. The Mw 7.5 event produced the largest recorded surface displacements of consistent 7 to 8 m left-lateral offsets. Along both ruptures, the surface trace followed tectonic geomorphic features that would have been recognized in pre-rupture mapping such as linear swales, saddles, and side-hill benches. However, in other areas the ruptures are expressed by breaks across the tops of shutter ridges, through bedrock knobs, and complex arrays of en echelon pressure ridges. Our efforts provide field validation of slip estimates determined by other methods (i.e. radar image analysis) and contribute to the overall assessment of the surface slip distribution. Additionally, the mapping observations highlight challenges in assessing surface fault rupture hazards.

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: Richard D. Koehler

Student Presenter: No

Additional Authors