Multi-scale rupture growth with alternating directions in a complex fault network during the 2023 south-eastern Türkiye and Syria earthquake doublet

Abstract

A devastating doublet of earthquakes with moment magnitude Mw 7.9 and Mw 7.6 earthquakes contiguously occurred in south-eastern Türkiye near the north-western border of Syria. Here we perform a potency-density tensor inversion to simultaneously estimate rupture evolution and fault geometry for the doublet. We find the initial Mw 7.9 earthquake involves a supershear back-rupture propagation, which is triggered by the initial bifurcated-fault rupture along a splay of the East Anatolian Fault and triggers the rupture in the southwest. The second Mw 7.6 event is triggered by the adjacent Mw 7.9 event, and it also involves supershear rupture along the favorably curved fault, which however is immediately stopped by geometric barriers in the fault ends. Our results highlight the multi-scale cascading rupture growth across the complex fault network that affects the diverse rupture geometries of the 2023 Türkiye earthquake doublet, contributing to the strong ground shaking and associated devastation.

Transient, accelerating slow slips drive the Preparatory Process of the 2023 Mw 7.8 Türkiye Earthquake

“…3b) interspersed with other of low coupling (i.e., #2 and #4). Note that the main asperity of the Mw 7.8 EQ is located the first 100 km north of the hypocenter [14][15][16]18 in between #2 and #3 (Fig. 3b).…”

“…Then, the rupture propagated to the Pazarcık segment and proceeded first northwards on the Pazarcık and Erkenek segments and then southwards on the Amanos segment (Supplementary Fig. S1) 14,16,18 . Worth to mention, the Mw 7.8 event broke a main asperity on the Pazarcık segment in proximity of the hypocenter [14][15][16]18 Looking at the recent past seismic activity in the region, the most significant earthquake was the January 2020 Mw 6.8 Elazığ earthquake 8,[20][21][22][23] , which took place in the northern part of the EAF.…”

“…S1) 14,16,18 . Worth to mention, the Mw 7.8 event broke a main asperity on the Pazarcık segment in proximity of the hypocenter [14][15][16]18 Looking at the recent past seismic activity in the region, the most significant earthquake was the January 2020 Mw 6.8 Elazığ earthquake 8,[20][21][22][23] , which took place in the northern part of the EAF. The latter earthquake was mainly a left-lateral strike-slip, with a small portion of source slip presenting a down-dip behavior 22 .…”

Decoding stress patterns of the 2023 Turkey-Syria earthquake doublet

“…Notably, the 2020 Mw 6. 7 Elazig earthquake, which occurred near the 2023 Mw 7.8 earthquake rupture's northeastern end (Güvercin et al, 2023;Okuwaki et al, 2023), was absent from Sunbul's (2019) stress calculations (Fig. 1).…”

“…1). Both shallow-depth main shocks (10km-14.5km) generated intense ground motion, leading to catastrophic regional impacts (USGS 2023a, b; Melgar et al, 2023;Okuwaki et al, 2023;Mai et al, 2023).…”