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Surface Expression of the Narlı and East Anatolian Fault Rupture Intersection in the 2023 M7.8 Pazarcık, Türkiye Earthquake

Description: 

Field observations of surface rupture and displacement in multisegment or multifault earthquakes contribute to our understanding of how rupture initiation, propagation, and arrest are expressed at the earth’s surface. The 2023 M7.8 Pazarcık earthquake in southeastern Türkiye represents a unique case of rupture initiation on the subsidiary Narlı fault, northward propagation, and triggering of bilateral East Anatolian fault (EAF) rupture. We evaluate this rupture sequence using field observations. In June 2023, we mapped parts of the M7.8 earthquake rupture north of the epicenter and recorded 68 measurements of left-laterally displaced cultural and natural features. We focused on a 30-km-long reach of the EAF that lacked previous field or remote observations of surface rupture and included the projected intersection with the northernmost Narlı fault. Field data show 10 km of previously unobserved EAF surface rupture northeast of Çiğli that is laterally continuous, locally distributed, and right stepping. Left-lateral EAF offset measurements range from ~1.8 to 6.8 m. Along a northeastern extension of the Narlı fault near Tetirlik, we observed 5 km of subtle and discontinuous rupture with 0.3–0.7 m of left-lateral displacement. We infer that EAF–Narlı fault interaction is expressed as 1) northeast-trending scarps along the eastern of two possible Narlı fault connections inferred from satellite observations, 2) a change in EAF displacement from ~2–5 m southwest to 6–7 m northeast of this intersection, and 3) a decrease in the lateral continuity of the EAF surface rupture at this projected intersection. This work highlights the importance of making systematic field-based rupture observations as it provides key data to constrain the kinematics of the M7.8 EAF rupture and provides benchmark field observations for comparison to remotely sensed displacement data.

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

Type: Oral

Date: 5/2/2024

Presentation Time: 08:45 AM (local time)

Presenting Author: Christopher

Student Presenter: No

Invited Presentation: 

Authors