Fault geometry and stress field around the 2023 Turkey earthquake doublet
Two Mw＞7 earthquakes occurred near the East Anatolia fault(EAF)in southeast region of Turkey in 2023.Distribution and focal mechanism of a large number of occurred aftershocks provide a good foundation for estimating the fault geometry and regional stress field in the southeast segments of the EAF.In this study,the refined positioning result of the aftershocks of the earthquake sequence is collected,the geometry parameters of the 8 sub-faults in 8 clustering zones are estimated by using the method of fuzzy clustering and fault plane estimating.The results show that the 4 steep sub-faults of the Mw7.8 earthquake are dipping to the northwest,which consistent with the dip of the northeast section of the EAF;the main fault area of the Mw7.6 earthquake is dip to the north,with 2 opposite dip direction and NE,NNE azimuth sub-faults at the west end and 1 dipping opposite to the EAF and NE azimuth sub fault at the east end.Then the earthquake focal mechanism around the Turkey double strong earthquakes was collected,and the stress field at each sub-region was calculated.It is found that the northeastern rupture region of the Mw7.8 earthquake presents the strike-slip stress state with NE-SW compression and NW-SE extension,which shows the strike-slip movement of EAF caused by the oblique pushing of the Arabian plate against the Anatolia plate.The southwest rupture zone of the Mw7.8 is characterized by east-west stretching and south-upward or north-downward extrusion processes.It is located at the triple junction of the Arabian Plate,the African plate and the Anatolian block,in which the stress state reflects the EW stretching state caused by the northward pushing of the African and Arabian plates and the forced westward migration of the Anatolian block.The stress field of the Mw7.6 earthquake rupture zone,which located in the Anatolian block,is characterized by the process of near NS extrusion and west-downward extension,which reflecting the pushing action of the Arabian plate and the African plate and the westward extension of the block.The stress field of the main area of the earthquake rupture is projected to the nodal planes of the central focal mechanism of the two earthquakes.It is found that the stress release direction of the Mw7.8 earthquake is consistent with the direction of the tectonic stress field,while the stress release direction of the Mw7.6 earthquake is quite different from that of the tectonic stress field,indicating that Mw7.6 may be triggered by the Mw7.8 earthquake.
Turkey earthquake doubletsGeometry of fault systemEarthquake clusteringFocal mechanismStress field
万方数据
维普
