Numerical simulation of 3-D mantle flow evolution in subduction zone environments in relation to seismic anisotropy beneath the eastern Mediterranean region

Zhao

Geochem Geophys Geosyst

et al. 2019

High‐resolution images of P‐wave anisotropic tomography beneath the Eastern Mediterranean and Middle East are determined by inverting a large number of high‐quality P‐wave arrival times. Our results clearly show along‐strike variations of subducting slabs in the Hellenic subduction zone. At least three high‐velocity anomalies are imaged beneath and behind the north Hellenides, which are associated with the subducting Hellenic slab at different stages, while in regions further south, a single slab is revealed that has subducted down to a depth of ~1,100 km. The slab feature is not prominent in the Cyprus subduction zone, but a fine‐scale high‐velocity structure is revealed beneath the central Anatolia, which may reflect the detached Cyprus slab. Trench‐parallel fast‐velocity directions occur in the forearc mantle wedge of the Hellenic subduction zone, which may reflect mantle flow induced by slab curvature. In the backarc north Aegean and westernmost Anatolia, dominant NNE‐SSW to N‐S fast‐velocity directions exist in the shallow mantle, which accord well with the extensional direction of present deformation at the surface, suggesting a vertically coherent deformation in the lithosphere. Our results reveal a large‐scale mantle flow beneath western Arabia, which is possibly related to the Zagros and Caucasus orogens and westward motion of the Anatolia lithosphere. The Arabian lithospheric plate is thinner beneath the Zagros than that under the Mesopotamian Foredeep, suggesting that a large portion of the crust was scrapped off from the subducted Arabian lithosphere during the Zagros orogen.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mantle Dynamics of the Eastern Mediterranean and Middle East: Constraints From P‐Wave Anisotropic Tomography

Zhao

Geochem Geophys Geosyst

et al. 2019

“…Furthermore, owing to its high seismic risk and significance for Eurasian and Mediterranean tectonics, Anatolia has been the natural laboratory for multidisciplinary observational studies involving source parameters of historical and modern earthquakes that leverage an array of advanced seismological tools, as well as mapping neotectonics and morphological features along with tomographic, geodynamic and geodetic modelling (e.g. Ambraseys 1989;Taymaz et al, 1991;Tan and Taymaz 2006;Taymaz et al, 2004 and2007a, b;Vanacore et al, 2013;Fielding et al, 2013;Duman and Emre, 2013;Fichtner et al, 2013;Kind et al, 2015;Confal et al, 2018). Previous strong events along the EAFZ include the 1964Malatya Ms 5.7, 1971Bingöl Ms 6.9, 1986Doğanşehir-Malatya Ms 5.9, 2003Bingöl Mw 6.3, 2004Sivrice Mw 5.5, and 2010 Kovancılar-Elazığ Mw 6.1 earthquakes.…”

Section: Fig 1 Relief Map Of Eastern Anatolia Showing the East Anatmentioning

confidence: 99%

Rupture Kinematics of January 24, 2020 Mw 6.7 Doğanyol-Sivrice, Turkey Earthquake on the East Anatolian Fault Zone Imaged by Space Geodesy

Melgar,

Ganas,

Taymaz

et al. 2020

Preprint

Self Cite

Here we present the results of a kinematic slip model of the 2020 Mw 6.7 Doğanyol-Sivrice, Turkey Earthquake, the most important event in the last 50 years on the East Anatolian Fault zone. Our slip model is constrained by two Sentinel-1 interferograms and by 5 three-component high-rate GNSS recordings close to the earthquake source. We find that most of the slip occurs predominantly in three regions, two of them at between 2 and 10 km depth and a deeper slip region extending down to 20 km depth. We also relocate the first two weeks of aftershocks and find a distribution of events that agrees with these slip features. The HR-GNSS recordings suggest a strongly unilateral rupture with the effects of a directivity pulse clearly seen in the waveforms and in the measure peak ground velocities. The slip model supports rupture propagation from northeast to southwest at a relatively slow speed of 2.2 km/s and a total source duration of ~20s. In the absence of near-source seismic stations, space geodetic data provide the best constraint on the spatial distribution of slip and on its time evolution.

Geochem Geophys Geosyst

“…A force couple arises from the differential along-strike subduction dynamics, following a terminology consistent with Sternai et al, 2016, where indentation and suction acts on the upper plate, and lateral motions or rotations in upper plate (Capitanio, 2014) and mantle flow (Sternai et al, 2016) are the result. Similar models have been applied to the coupling between subduction, mantle flow and extrusion and thickening, and seismic anisotropy in Asia and eastern Mediterranean (Capitanio, 2014(Capitanio, , 2016Confal et al, 2018;Magni et al, 2014;Pusok & Kaus, 2015;Sternai et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Current Deformation in the Tibetan Plateau: A Stress Gauge in the India‐Asia Collision Tectonics

Capitanio

2020

Geodetic velocities and mantle seismic anisotropy provide relevant constraints to the dynamics of the Asian continent. Here, these are compared to numerical models of subduction, collision, and upper plate deformation, developing features similar to the present‐day India‐Asia region. Varying buoyancy and far‐field forces, the models provide coupled surface and mantle motions and deformation allowing a first‐order agreement to the observables in the Tibetan area. Observed trends are reproduced when the pull from the Indian slab vanishes and the neighboring southeast Asian slab drives extrusion in eastern Tibet, matching GPS rotation and convergence‐perpendicular component, and a far‐field force acts to increase the GPS convergence‐parallel component and lithospheric thickening observed in the Tian Shan‐Tibetan domain. The net force exerted on the Tibetan lithosphere is ~2.6 × 1012 N/m, mostly due to neighboring southeast Asian subduction, and raises to ~2.8 × 1012 N/m, when additional far‐field forces apply. Largest suction force exerted on the Sunda margin is ~2.4 × 1012 N/m, whereas the comparison to seismic anisotropy supports the idea that the mantle is passive. These are interpreted in the context of the differential along‐strike dynamics of the Indian‐southeast Asian subduction: The coupled indentation‐suction along the plate margin drives large‐scale extrusion, while the excess stress along the Indian margin is accommodated by Tibetan lithospheric thickening. The models constrain the boundary forces and lithospheric processes of the Asian tectonics and emphasize the role of large‐scale coupling of the Indian margin and the southeast Asian subduction.