The 2023 Southeast Türkiye Seismic Sequence: Rupture of a Complex Fault Network

Abstract

On 6 February 2023, southeastern Türkiye experienced two Mw 7.7 and 7.6 earthquakes. The earthquake sequence caused widespread damage and tens of thousands of casualties in Türkiye and Syria. We analyze mainshocks and aftershocks, combining complementary source characterization techniques, relying on local, regional, and teleseismic data. Backprojection analysis and finite source inversion for the mainshocks resolve coseismic slip, rupture length, and propagation mode along the main faults, whereas centroid moment tensor inversion for 221 aftershocks resolves details of the fault network. The first mainshock nucleated on a splay fault and activated the neighboring East Anatolian fault zone (EAFZ). It ruptured bilaterally along ∼500 km first toward northeast and later to south-southwest on multiple, previously partly dormant fault segments. The second mainshock ruptured the east–west-oriented Sürgü-Misis fault zone (SMFZ), reaching a slip of 7 m. The analysis of aftershocks with heterogeneous moment tensors retrospectively reconstructs rupture details. Along the main strand of the EAFZ, they map the geometry of different segments in unprecedented detail, whereas along the SMFZ they illuminate the geometry and behavior of large structures for the first time. Our work sheds light on multiple aspects of rupture evolution and provides new insights into the devastating earthquake sequence.

Months-long seismicity transients preceding the 2023 MW 7.8 Kahramanmaraş earthquake, Türkiye

“…Surface ruptures as reported by USGS map and ref. 34 . The focal mechanisms display the estimated moment tensor for these earthquakes from GEOFON (lower hemisphere projection).…”

“…4, see also 25 ). Interestingly, coseismic slip during the mainshock was the largest around this segment 34 , signifying a large stress accumulation on this segment during the interseismic period. In contrast, the Pütürge segment of the EAFZ displayed abundant seismicity during this time period, including a M W 4.5 earthquake and its corresponding aftershock sequence from January 15th (orange star in Fig.…”

The overall-subshear and multi-segment rupture of the 2023 Mw7.8 Kahramanmaraş, Turkey earthquake in millennia supercycle

“…Mai et al 18 perform beam-forming BP and report a V NE of 3.1 km/s and a V SW of 2 km/s. Petersen et al 19 utilize finite source inversion and BP techniques, revealing an average velocity range of 1.8-2.6 km/s and a maximum velocity of 3.4 km/s. Yao & Yang 20 determine a V SW range of 3.1-3.4 km/s and a V NE of ~3.19 km/s through near-field data analysis and numerical rupture simulations.…”

The Investigation of Tropospheric Changes with GNSS: A study on 6 February 2023 Kahramanmaraş Earthquake Sequence

“…To be able to understand the fault behavior, main and aftershocks (Okuwaki et al, 2023;Petersen et al, 2023;Karabulut et al, 2023;Güvercin 2024), also combination of aftershocks with GNSS data (Melgar et al, 2023) are studied with rupture analysis. GNSS data is also used to calculate the coseismic and early postseismic deformation analysis of the earthqukes (Özarpacı et al, 2023; Özkan et al, 2023).…”