首页|Relationship between seismic structures and the diverse rupture processes of the 2023 Türkiye earthquake doublet
Relationship between seismic structures and the diverse rupture processes of the 2023 Türkiye earthquake doublet
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Relationship between seismic structures and the diverse rupture processes of the 2023 Türkiye earthquake doublet
Recent geodetic and seismological observations of two major earthquakes in southeastern Türkiye in February 2023 have revealed complex rupture initiation,propagation,and segmentation along the East Anatolian Fault Zone(EAFZ)and surrounding regions.However,the role of upper crust structures along the EAFZ in determining the diverse rupture processes of this earthquake doublet remains unclear.To further investigate this,we employed double-difference location and seismic tomography techniques to determine high-resolution seismic velocities(VP,VS)and Poisson's ratio(σ)structures using a multi-parameterjoint tomographic algorithm.Our dataset includes 100,833 high-quality source-receiver travel-time pairs of P-and S-waves.We find that the unique rupture processes of this earthquake doublet were primarily influenced by contrasting crustal seismic structures and localized geological settings.The Mw7.8 mainshock was initiated within a transitional edge zone char-acterized by a rigid part(asperity)of the seismogenic zone with sharp contrast variations in rock strength ranging from low to high along the EAFZ.In comparison,the Mw7.6 rupture originated in a ductile belt featuring fluid saturation with low-VP,low-VS,and high-σ values that extended parallel to the Çardak Fault.The pronounced contrast structures observed along the former rupture can be attributed to the oblique collision system between the weakened section of the east Anatolian plateau and the brittle Arabian platform,while the latter rupture was initiated within the ductile structure associated with fluid intrusion caused by the northward subduction of the Cyprus slab and subsequent detachment.Furthermore,the occurrence of the first earthquake(E1)serves to alleviate shear stress on the second earthquake(E2)fault,potentially impeding the initiation of an E2 rupture.On the contrary,this event also significantly reduces the normal stress acting on the E2 fault due to a double left-lateral strike-slip system within a triangular region.This reduction not only results in a decrease of fault friction force and an increase in rock porosity but also induces lower strain drops and the redistribution of Coulomb stress,thereby contributing to the initiation of the E2 event.The proposed rupture pattern exceeds the conventional model that governs individual earthquake ruptures,offering new insights for mitigating potential seismic disasters in Türkiye.The lessons learned from this doublet event can contribute to reevaluating the ongoing risk of damaging earthquakes in China's South-North Seismic Zone or other regions worldwide with comparable geological conditions.
CAS Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China
Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China
University of Chinese Academy of Sciences,Beijing 100049,China
Key Laboratory of Tibetan Plateau Earth System,Environment and Resources(TPESER),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China
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2023 Türkiye earthquake doublet Joint seismic tomography Tomographic transition edge Seismic rupture process Strong fault coupling
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