SUMMARYWe analysed coseismic surface displacements of the 2020 January 24 Elazığ (M 6.75) Earthqu... more SUMMARYWe analysed coseismic surface displacements of the 2020 January 24 Elazığ (M 6.75) Earthquake using GPS (Global Positioning System) measurements to investigate the associated fault slip distribution and static stress change. Our geodetic analysis of 13 GPS sites surrounding the epicentre included data from four additional sites. We accurately located the nucleation point of the main shock at 38.310° N, 39.081° E (±1.4 km) and at a depth of 5.2 ± 1.2 km. Both seismograph and GPS-derived fault plane solutions confirmed that it has a nearly pure sinistral mechanism with a negligible obliquity. The main shock generated 29.2 cm average sinistral slip along an approximately 70 km long and 20 km wide section of the East Anatolian Fault. Based on its rupture size and average slip, its magnitude was found to be Mw 6.75. An average of 6.6 bars of stress drop occurred on the rupture plane. The rupture occurred bilaterally failing two separate segments both to the northeast and to the southwest of the nucleation point. Average sinistral slips were 14.6 and 47.4 cm along the southwestern and northeastern segments, respectively. Sinistral slip reached up to 53.1 cm along the southwestern segment and 110.5 cm along the northeastern segment. During the generation process of the 2020 earthquake, 78 per cent of the slip deficit had been released aseismically since 1875. Increasing Coulomb stress by an average of 2.5 bars, it substantially increased earthquake hazard on the 1874 (M 7.1) rupture zone, which might have already accumulated 1.51 m slip deficit on its fully locked patches. Furthermore, increasing Coulomb stress by an average of 0.5 bars, it raised earthquake hazard on the 1893 (M 7.1) rupture zone, which might have already stored 1.01 m slip deficit along the fully locked patches.
This paper aims to present a new neotectonic perspective concordant with the seismic activities i... more This paper aims to present a new neotectonic perspective concordant with the seismic activities in Turkey and surrounding regions. The neotectonic structures have been re-evaluated mainly by using focal mechanism solutions and high-resolution satellite (Google Earth) images. The Southeast Anatolian Wedge explains thrust/blind thrust and asymmetrical folding relationship in SE Turkey, Syria, and Northern Iraq. The neotectonic structures of the Turkish-Iranian Plateau are enlightened by the rhomboidal cell model which creates a base to determine multiple intersection points between the region-wide left- and right-lateral shear zones. The releasing stepover between the North Anatolian Fault Zone and Southeast Anatolian-Zagros Fault Zone plus their connections with the Northeast Anatolian Fault Zone and the East Anatolian Fault Zone are described in a more meaningful way with the Anatolian Diagonal concept. It also clarifies the role of left-lateral shear zone in the west-southwest move...
To investigate contemporary crustal deformation in Turkey, we compute velocity field in a frame f... more To investigate contemporary crustal deformation in Turkey, we compute velocity field in a frame fixed to Eurasia at 316 point within the conterminus Turkey from Global Positioning System(GPS) measurements between the years 1992 and 2002. The resulting velocity field reveals decoupling Anatolian plate from Eurasia along dextral North Anatolian Fault(NAF). Velocities indicating westward motion of Anatolia increase gradually from 20
We use Global Positioning System (GPS) observations and elastic half-space models to estimate the... more We use Global Positioning System (GPS) observations and elastic half-space models to estimate the distribution of coseismic and postseismic slip along the Izmit earthquake rupture. Our results indicate that large coseismic slip (reaching 5.7 meters) is confined to the upper 10 kilometers of the crust, correlates with structurally distinct fault segments, and is relatively low near the hypocenter. Continued surface deformation during the first 75 days after the earthquake indicates an aseismic fault slip of as much as 0.43 meters on and below the coseismic rupture. These observations are consistent with a transition from unstable (episodic large earthquakes) to stable (fault creep) sliding at the base of the seismogenic zone.
SUMMARYWe analysed coseismic surface displacements of the 2020 January 24 Elazığ (M 6.75) Earthqu... more SUMMARYWe analysed coseismic surface displacements of the 2020 January 24 Elazığ (M 6.75) Earthquake using GPS (Global Positioning System) measurements to investigate the associated fault slip distribution and static stress change. Our geodetic analysis of 13 GPS sites surrounding the epicentre included data from four additional sites. We accurately located the nucleation point of the main shock at 38.310° N, 39.081° E (±1.4 km) and at a depth of 5.2 ± 1.2 km. Both seismograph and GPS-derived fault plane solutions confirmed that it has a nearly pure sinistral mechanism with a negligible obliquity. The main shock generated 29.2 cm average sinistral slip along an approximately 70 km long and 20 km wide section of the East Anatolian Fault. Based on its rupture size and average slip, its magnitude was found to be Mw 6.75. An average of 6.6 bars of stress drop occurred on the rupture plane. The rupture occurred bilaterally failing two separate segments both to the northeast and to the southwest of the nucleation point. Average sinistral slips were 14.6 and 47.4 cm along the southwestern and northeastern segments, respectively. Sinistral slip reached up to 53.1 cm along the southwestern segment and 110.5 cm along the northeastern segment. During the generation process of the 2020 earthquake, 78 per cent of the slip deficit had been released aseismically since 1875. Increasing Coulomb stress by an average of 2.5 bars, it substantially increased earthquake hazard on the 1874 (M 7.1) rupture zone, which might have already accumulated 1.51 m slip deficit on its fully locked patches. Furthermore, increasing Coulomb stress by an average of 0.5 bars, it raised earthquake hazard on the 1893 (M 7.1) rupture zone, which might have already stored 1.01 m slip deficit along the fully locked patches.
This paper aims to present a new neotectonic perspective concordant with the seismic activities i... more This paper aims to present a new neotectonic perspective concordant with the seismic activities in Turkey and surrounding regions. The neotectonic structures have been re-evaluated mainly by using focal mechanism solutions and high-resolution satellite (Google Earth) images. The Southeast Anatolian Wedge explains thrust/blind thrust and asymmetrical folding relationship in SE Turkey, Syria, and Northern Iraq. The neotectonic structures of the Turkish-Iranian Plateau are enlightened by the rhomboidal cell model which creates a base to determine multiple intersection points between the region-wide left- and right-lateral shear zones. The releasing stepover between the North Anatolian Fault Zone and Southeast Anatolian-Zagros Fault Zone plus their connections with the Northeast Anatolian Fault Zone and the East Anatolian Fault Zone are described in a more meaningful way with the Anatolian Diagonal concept. It also clarifies the role of left-lateral shear zone in the west-southwest move...
To investigate contemporary crustal deformation in Turkey, we compute velocity field in a frame f... more To investigate contemporary crustal deformation in Turkey, we compute velocity field in a frame fixed to Eurasia at 316 point within the conterminus Turkey from Global Positioning System(GPS) measurements between the years 1992 and 2002. The resulting velocity field reveals decoupling Anatolian plate from Eurasia along dextral North Anatolian Fault(NAF). Velocities indicating westward motion of Anatolia increase gradually from 20
We use Global Positioning System (GPS) observations and elastic half-space models to estimate the... more We use Global Positioning System (GPS) observations and elastic half-space models to estimate the distribution of coseismic and postseismic slip along the Izmit earthquake rupture. Our results indicate that large coseismic slip (reaching 5.7 meters) is confined to the upper 10 kilometers of the crust, correlates with structurally distinct fault segments, and is relatively low near the hypocenter. Continued surface deformation during the first 75 days after the earthquake indicates an aseismic fault slip of as much as 0.43 meters on and below the coseismic rupture. These observations are consistent with a transition from unstable (episodic large earthquakes) to stable (fault creep) sliding at the base of the seismogenic zone.
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