On February 6, 2023, the doublet earthquake including two main shocks with magnitudes MW7.8 and MW7.5, occurred near the western side of the East Anatolian Fault at the southeast boundary of the Anatolian Plateau in T...On February 6, 2023, the doublet earthquake including two main shocks with magnitudes MW7.8 and MW7.5, occurred near the western side of the East Anatolian Fault at the southeast boundary of the Anatolian Plateau in Turkey. Based on the WGM2012 Bouguer gravity anomaly data and the Etopo1topography data, this study first introduced a joint inversion of admittance and coherence functions and used the Bayesian optimal parameter estimation method to obtain the effective elastic thickness Teand loading ratio F of the lithosphere for various tectonic units in the Anatolian Plateau. Secondly, we discussed the characteristics and influencing factors of the lithospheric mechanical strength and analyzed its relationship with seismic activity. The lithospheric mechanical strength of the Anatolian Plateau showed clear lateral heterogeneity and a "weak-strong-weak" spatial pattern from east to west,reflecting various tectonic processes. At last, the strong seismic activity was found where the lithospheric strength was low in the Anatolian Plate. We also incorporated GPS strain rate and other results to investigate the tectonic background and primary causes of the MW7.8 and MW7.5 doublet earthquakes in Turkey. The results have a good insight into urban safety design in the Turkish region, including postdisaster rehabilitation, earthquake hazard assessment, and loss reduction.展开更多
Anatolia is the global archetype of tectonic escape,as witnessed by the devastating 2023 KahramanmaraşEarthquake sequence,and the 2020 Samos Earthquake,which show different kinematics related to the framework of the e...Anatolia is the global archetype of tectonic escape,as witnessed by the devastating 2023 KahramanmaraşEarthquake sequence,and the 2020 Samos Earthquake,which show different kinematics related to the framework of the escape tectonics.Global Positioning System(GPS)motions of the wedge-shaped plate differ regionally from northwestwards to southwestwards(from east to west).Anatolia was extruded westward from the Arabian-Eurasian collision along the North and East Anatolian fault systems,rotating counterclockwise into the oceanic free-faces of the Mediterranean and Aegean,with dramatic extension of western Anatolia in traditional interpretations.However,which is the dominant mechanism for this change in kinematics,extrusion related to the Arabia/Eurasia collision or rollback of the African slab beneath western Anatolia is still unclear.To assess the dominant driving mechanisms across Anatolia,we analyze recent GPS velocity datasets,and decomposed them into N-S and E-W components,revealing that westward motion is essentially constant across the whole plate and consistent with the slip rates of the North and East Anatolia fault zones,while southward components increase dramatically in the transition area between central and western Anatolia,where a slab tear is suggested.This phenomenon is related to different tectonic driving mechanisms.The ArabiaEurasia collision drives the Anatolian Plate uniformly westwards while western Anatolia is progressively more affected by the southward retreating African subducting slab west of the Aegean/Cypriot slab tear,which significantly increases the southward component of the velocity field and causes the apparent curve of the whole modern velocity field.The 2020 and 2023 earthquake focal mechanisms also confirm that the northward colliding Arabian Plate forced Anatolia to the west,and the retreating African slab is pulling the upper plate of western Anatolian apart in extension.We propose that the Anatolian Plate is moving westwards as one plate with an additional component of extension in its west caused by the local driving mechanism,slab rollback(with the boundary above the slab tear around Isparta),rather than separate microplates or a near-pole spin of the entire Anatolian Plate,and the collisionrelated extrusion is the dominant mechanism of tectonic escape.展开更多
Both M_(W) 7.8 and M_(W) 7.5 earthquakes occurred in southeastern Türkiye on February 6,2023,resulting in numerous buildings collapsing and serious casualties.Understanding the distribution of coseismic surface r...Both M_(W) 7.8 and M_(W) 7.5 earthquakes occurred in southeastern Türkiye on February 6,2023,resulting in numerous buildings collapsing and serious casualties.Understanding the distribution of coseismic surface ruptures and secondary disasters surrounding the epicentral area is important for post-earthquake emergency and disaster assessments.High-resolution Maxar and GF-2 satellite data were used after the events to extract the location of the rupture surrounding the first epicentral area.The results show that the length of the interpreted surface rupture zone(part of)is approximately 75 km,with a coseismic sinistral dislocation of 2-3 m near the epicenter;however,this reduced to zero at the tip of the southwest section of the East Anatolia Fault Zone.Moreover,dense soil liquefaction pits were triggered along the rupture trace.These events are in the western region of the Eurasian Seismic Belt and result from the subduction and collision of the Arabian and African Plates toward the Eurasian Plate.The western region of the Chinese mainland and its adjacent areas are in the eastern section of the Eurasian Seismic Belt,where seismic activity is controlled by the collision of the Indian and Eurasian Plates.Both China and Türkiye have independent tectonic histories.展开更多
Tors are mound-like rock landforms,resistant to erosion,that may sometimes reach the size of several storeys of house by volume.They may develop in different climate regions and different rock types,led by granitic ro...Tors are mound-like rock landforms,resistant to erosion,that may sometimes reach the size of several storeys of house by volume.They may develop in different climate regions and different rock types,led by granitic rocks.In this study,tors developed in granitic rocks around Yaylal?village linked to Kürtün county in Gümü?hane were investigated.The study area is located in the eastern part of the Giresun mountain range in northeastern Turkey,2000-2300 m above sea level.The aim of the study is to determine the natural environmental characteristics in tor formation and to reveal the effect of bedrock on tor formation.During field studies,18 tors were selected by noting location,size and structural features,and dimensions were measured.Thin sections were first made from the rock samples taken from the tors and then the mineralogical composition was investigated by modal analysis method.As a result of this analysis,it was determined that the bedrock forming the tors is granite.During the field observations,it was determined that the intersecting vertical joints supported the formation of castle-like tors,while the horizontal joints supported the formation of pita pileshaped tors.There are also pseudokarstic shapes resembling kamenitza and karst pavement.In conclusion,joint sets causing local resistance differences directed the formation of tors,while excess slope affected surface erosion and suitability of climate conditions-controlled weathering rate.展开更多
Studies on differentiation of ensimatic arc units from melange units in the Northern Anatolian Ophiolitic Belt(NAOB) are very rare. The study area represents the southern edge of the central part of the NAOB.The aim o...Studies on differentiation of ensimatic arc units from melange units in the Northern Anatolian Ophiolitic Belt(NAOB) are very rare. The study area represents the southern edge of the central part of the NAOB.The aim of the study is to distinguish the main units of NAOB and to define the geotectonic setting of the Darmik Ensimatic Arc Association(DEAA). To study the ensimatic arc units as an independent tectonic unit is important and facilitates understanding of the geological evolution of the NAOB. During field studies, the contact relationships within the Darmik Ensimatic Arc Association(DEAA) units and also with other tectonic units were reviewed. Then, paleontological, geochronological, petrological and also geochemical properties of the DEAA have been defined. In the present study, ensimatic arc units have been distinguished from ophiolitic association for the first time, in the region. As a result of the study, the DEAA is divided into two levels and lower level named as the Kartal unit and upper level named as the izibüyük unit. In the Kartal unit, basaltic and andesitic lavas with their equivalent pyroclastic rock units are dominant. Radiolarite and mudstones interbedded within the Kartal unit of DEAA have Turonian and Santonian age. In addition, the age of basalt samples of DEAA are 98.7 ± 2.4 Ma, defined using the^(40)Ar/39 Ar method. The izibüyük unit of DEAA comprises conglomerate, sandstone, claystone, mudstone,clayey limestone, micritic limestone with volcanic interbeds and also calciturbidites. Santonian-Maastrichtian ages were obtained from this unit of the DEAA. In conclusion, the age of DEAA is widely accepted as Late Cretaceous. After the evaluation of the analysis, the volcanics of the DEAA originated from calcalkaline-basalts, which reflect ensimatic arc magmatism.展开更多
We investigated the effects of precommercial thinning(PCT)applied at different levels on the growth parameters of natural Anatolian black pine stand.The experimental site was located in the province of Isparta in sout...We investigated the effects of precommercial thinning(PCT)applied at different levels on the growth parameters of natural Anatolian black pine stand.The experimental site was located in the province of Isparta in southern Turkey.PCT was set up using a randomized complete block design with three replicates and three treatments(control,2–2.5 m×–2.5 m and 3–3.5 m×–3.5 m spacing).The experimental plots were established in March 2014.At the end of the growing seasons for three years(2014–2016),growth parameters such as diameter,height and crown radius were measured.PCT was found to be significantly effective on diameter,height,individual tree basal area,and crown radius increment at the end of the third year(p<0.05).While diameter,individual tree basal area and crown radius increment increased with increasing PCT intensity,height increment was higher in control than PCT.Although the PCT treatments applied with 3–3.5 m spacing affected individual tree development positively,we need long-term results on wood quality and yield.According to the short-term results,it is thought that it is better to lower the stand closeness gradually,so,it may be advisable to apply PCT by 2–2.5 m×–2.5 m spacing.展开更多
基金funded by the National Natural Science Foundation of China (Grant Nos.U1939205,41974095)the Basic Research Fund of the Institute of Geophysics,China Earthquake Administration (Grant Nos.DQJB21R30)。
文摘On February 6, 2023, the doublet earthquake including two main shocks with magnitudes MW7.8 and MW7.5, occurred near the western side of the East Anatolian Fault at the southeast boundary of the Anatolian Plateau in Turkey. Based on the WGM2012 Bouguer gravity anomaly data and the Etopo1topography data, this study first introduced a joint inversion of admittance and coherence functions and used the Bayesian optimal parameter estimation method to obtain the effective elastic thickness Teand loading ratio F of the lithosphere for various tectonic units in the Anatolian Plateau. Secondly, we discussed the characteristics and influencing factors of the lithospheric mechanical strength and analyzed its relationship with seismic activity. The lithospheric mechanical strength of the Anatolian Plateau showed clear lateral heterogeneity and a "weak-strong-weak" spatial pattern from east to west,reflecting various tectonic processes. At last, the strong seismic activity was found where the lithospheric strength was low in the Anatolian Plate. We also incorporated GPS strain rate and other results to investigate the tectonic background and primary causes of the MW7.8 and MW7.5 doublet earthquakes in Turkey. The results have a good insight into urban safety design in the Turkish region, including postdisaster rehabilitation, earthquake hazard assessment, and loss reduction.
基金funded by the National Natural Science Foundation of China(Nos.91755213 and 41888101)and the Chinese Scholarship Council.
文摘Anatolia is the global archetype of tectonic escape,as witnessed by the devastating 2023 KahramanmaraşEarthquake sequence,and the 2020 Samos Earthquake,which show different kinematics related to the framework of the escape tectonics.Global Positioning System(GPS)motions of the wedge-shaped plate differ regionally from northwestwards to southwestwards(from east to west).Anatolia was extruded westward from the Arabian-Eurasian collision along the North and East Anatolian fault systems,rotating counterclockwise into the oceanic free-faces of the Mediterranean and Aegean,with dramatic extension of western Anatolia in traditional interpretations.However,which is the dominant mechanism for this change in kinematics,extrusion related to the Arabia/Eurasia collision or rollback of the African slab beneath western Anatolia is still unclear.To assess the dominant driving mechanisms across Anatolia,we analyze recent GPS velocity datasets,and decomposed them into N-S and E-W components,revealing that westward motion is essentially constant across the whole plate and consistent with the slip rates of the North and East Anatolia fault zones,while southward components increase dramatically in the transition area between central and western Anatolia,where a slab tear is suggested.This phenomenon is related to different tectonic driving mechanisms.The ArabiaEurasia collision drives the Anatolian Plate uniformly westwards while western Anatolia is progressively more affected by the southward retreating African subducting slab west of the Aegean/Cypriot slab tear,which significantly increases the southward component of the velocity field and causes the apparent curve of the whole modern velocity field.The 2020 and 2023 earthquake focal mechanisms also confirm that the northward colliding Arabian Plate forced Anatolia to the west,and the retreating African slab is pulling the upper plate of western Anatolian apart in extension.We propose that the Anatolian Plate is moving westwards as one plate with an additional component of extension in its west caused by the local driving mechanism,slab rollback(with the boundary above the slab tear around Isparta),rather than separate microplates or a near-pole spin of the entire Anatolian Plate,and the collisionrelated extrusion is the dominant mechanism of tectonic escape.
基金funded by the Basic Research Program of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant Nos.CEAIEF20220102,2021IEF0505,and CEAIEF2022050502)the National Natural Science Foundation of China(Grant Nos.42072248 and 42041006)the National Key Research and Development Program of China(Grant Nos.2021YFC3000601-3 and 2019YFE0108900)。
文摘Both M_(W) 7.8 and M_(W) 7.5 earthquakes occurred in southeastern Türkiye on February 6,2023,resulting in numerous buildings collapsing and serious casualties.Understanding the distribution of coseismic surface ruptures and secondary disasters surrounding the epicentral area is important for post-earthquake emergency and disaster assessments.High-resolution Maxar and GF-2 satellite data were used after the events to extract the location of the rupture surrounding the first epicentral area.The results show that the length of the interpreted surface rupture zone(part of)is approximately 75 km,with a coseismic sinistral dislocation of 2-3 m near the epicenter;however,this reduced to zero at the tip of the southwest section of the East Anatolia Fault Zone.Moreover,dense soil liquefaction pits were triggered along the rupture trace.These events are in the western region of the Eurasian Seismic Belt and result from the subduction and collision of the Arabian and African Plates toward the Eurasian Plate.The western region of the Chinese mainland and its adjacent areas are in the eastern section of the Eurasian Seismic Belt,where seismic activity is controlled by the collision of the Indian and Eurasian Plates.Both China and Türkiye have independent tectonic histories.
文摘Tors are mound-like rock landforms,resistant to erosion,that may sometimes reach the size of several storeys of house by volume.They may develop in different climate regions and different rock types,led by granitic rocks.In this study,tors developed in granitic rocks around Yaylal?village linked to Kürtün county in Gümü?hane were investigated.The study area is located in the eastern part of the Giresun mountain range in northeastern Turkey,2000-2300 m above sea level.The aim of the study is to determine the natural environmental characteristics in tor formation and to reveal the effect of bedrock on tor formation.During field studies,18 tors were selected by noting location,size and structural features,and dimensions were measured.Thin sections were first made from the rock samples taken from the tors and then the mineralogical composition was investigated by modal analysis method.As a result of this analysis,it was determined that the bedrock forming the tors is granite.During the field observations,it was determined that the intersecting vertical joints supported the formation of castle-like tors,while the horizontal joints supported the formation of pita pileshaped tors.There are also pseudokarstic shapes resembling kamenitza and karst pavement.In conclusion,joint sets causing local resistance differences directed the formation of tors,while excess slope affected surface erosion and suitability of climate conditions-controlled weathering rate.
文摘Studies on differentiation of ensimatic arc units from melange units in the Northern Anatolian Ophiolitic Belt(NAOB) are very rare. The study area represents the southern edge of the central part of the NAOB.The aim of the study is to distinguish the main units of NAOB and to define the geotectonic setting of the Darmik Ensimatic Arc Association(DEAA). To study the ensimatic arc units as an independent tectonic unit is important and facilitates understanding of the geological evolution of the NAOB. During field studies, the contact relationships within the Darmik Ensimatic Arc Association(DEAA) units and also with other tectonic units were reviewed. Then, paleontological, geochronological, petrological and also geochemical properties of the DEAA have been defined. In the present study, ensimatic arc units have been distinguished from ophiolitic association for the first time, in the region. As a result of the study, the DEAA is divided into two levels and lower level named as the Kartal unit and upper level named as the izibüyük unit. In the Kartal unit, basaltic and andesitic lavas with their equivalent pyroclastic rock units are dominant. Radiolarite and mudstones interbedded within the Kartal unit of DEAA have Turonian and Santonian age. In addition, the age of basalt samples of DEAA are 98.7 ± 2.4 Ma, defined using the^(40)Ar/39 Ar method. The izibüyük unit of DEAA comprises conglomerate, sandstone, claystone, mudstone,clayey limestone, micritic limestone with volcanic interbeds and also calciturbidites. Santonian-Maastrichtian ages were obtained from this unit of the DEAA. In conclusion, the age of DEAA is widely accepted as Late Cretaceous. After the evaluation of the analysis, the volcanics of the DEAA originated from calcalkaline-basalts, which reflect ensimatic arc magmatism.
基金This study was a part of the doctoral dissertation and supported by Suleyman Demirel University Projects(Project numbers:OYP-05241-DR14 and 4167-OYP-D2-14).
文摘We investigated the effects of precommercial thinning(PCT)applied at different levels on the growth parameters of natural Anatolian black pine stand.The experimental site was located in the province of Isparta in southern Turkey.PCT was set up using a randomized complete block design with three replicates and three treatments(control,2–2.5 m×–2.5 m and 3–3.5 m×–3.5 m spacing).The experimental plots were established in March 2014.At the end of the growing seasons for three years(2014–2016),growth parameters such as diameter,height and crown radius were measured.PCT was found to be significantly effective on diameter,height,individual tree basal area,and crown radius increment at the end of the third year(p<0.05).While diameter,individual tree basal area and crown radius increment increased with increasing PCT intensity,height increment was higher in control than PCT.Although the PCT treatments applied with 3–3.5 m spacing affected individual tree development positively,we need long-term results on wood quality and yield.According to the short-term results,it is thought that it is better to lower the stand closeness gradually,so,it may be advisable to apply PCT by 2–2.5 m×–2.5 m spacing.