A comprehensive teleseismic shear-wave splitting dataset of 6,606 measurements is presented for the eastern Mediterranean.• Lithospheric anisotropy beneath the North Anatolian Fault is consistent with a mantle shear zone deforming coherently with the surface. 10• Asthenospheric anisotropy beneath Anatolia is dominated by relatively small-11 scale processes such as flow through slab gaps and tears.

<p>The eastern Mediterranean hosts, within the span of a few hundred kilometres, extensional, strike-slip, and collision tectonics above a set of fragmenting subducting slabs. Widespread Miocene-Recent volcanism and ~2km uplift has been attributed to mantle processes such as delamination, dripping and/or slab tearing/break-off. We investigate this complex region using a variety of broadband seismological techniques, with new P- and S-wave tomographic images in Kounoudis et al. (2020), seismic anisotropy constrained via an updated dataset of SKS shear-wave splitting observations in Merry et al. (2021), and crustal structure imaged by quality-controlled H-κ stacking of receiver functions in Ogden & Bastow (2021). Overall, seismic anisotropy and crustal structure are more spatially variable than previously recognised, and such variations correspond well with variations in mantle structure shown by the tomography. In general, Moho depth is poorly correlated with elevation, suggesting crustal thickness variations do not fully explain topographic differences, and residual topography calculations indicate the requirement for a mantle contribution to Anatolian Plateau uplift. Evidence for such a contribution exists in central Anatolia, where an imaged horizontal tear in the Cyprus slab spatially corresponds with volcanism, a residual topographic high, and a region of reduced splitting delay times and nulls, all consistent with upwelling of asthenospheric material through the tear. Anisotropic fast directions are consistent with flow through the imaged gap between the Cyprus and Aegean slabs, again correlating roughly with both volcanism and high residual topography. Slow uppermost‐mantle wave speeds below active volcanoes in eastern Anatolia, and ratios of P-to-S wave relative traveltimes, indicate a thin lithosphere and melt contributions. Elsewhere, there is more evidence for slab processes controlling mantle flow, with anisotropic fast directions diverted at the edges of imaged slabs and consistent with flow towards the retreating Hellenic trench in the Aegean. The North Anatolian Fault is revealed to be a deep, plate-scale structure: whilst there are no clear changes in Moho depth across the fault, deep velocity contrasts suggest a 40­-60km decrease in lithospheric thickness from the Precambrian lithosphere north of the fault to a thinned Anatolian lithosphere in the south. Moreover, short-length-scale variations in anisotropy and backazimuthal variations in splitting parameters at the fault indicate fault-related lithospheric deformation, with seismic fast directions either fault-parallel or intermediate between the principle extensional strain rate axis and fault strike, diagnostic of a relatively low-strained transcurrent mantle shear zone. Upper mantle structure thus exerts a strong influence on uplift, volcanism and deformation in Anatolia.</p><p><strong>References</strong></p><p>Kounoudis, R., I.D. Bastow, C.S. Ogden, S. Goes, J. Jenkins, et al.,  (2020), Seismic Tomographic Imaging of the Eastern Mediterranean Mantle..., <em>G<sup>3</sup></em>, <strong>21</strong>(7), doi:10.1029/2020GC009009.</p><p>Merry, T.A.J., I.D. Bastow, R. Kounoudis, C.S. Ogden, R.E. Bell, & L. Jones (2021), The influence of the North Anatolian Fault and a fragmenting slab architecture on upper mantle seismic anisotropy... ,<em>G<sup>3</sup></em>, <strong>22</strong>, doi:10.1029/2021GC009896.</p><p>Ogden, C.S., & I.D. Bastow (2021), The Crustal Structure of the Anatolian Plate from Receiver Functions..., <em>GJI</em>, doi:10.1093/gji/ggab513.</p>

<p>Cyprus sits at the plate boundary between Anatolia in the north and Africa in the south, at a transition from oceanic subduction in the west to continental strike-slip and collision tectonics in the east. The nature of the plate boundary at Cyprus has been historically controversial and poorly understood, in part due to a lack of constraints on local seismicity. Ongoing subduction of either oceanic or continental African lithosphere is argued, with some invoking subduction of the Eratosthenes Seamount, a continental fragment to the south of Cyprus rising 2km above the sea floor, as a driver of uplift in Cyprus. At the centre and highest point of the Troodos ophiolite, which dominates the island, is the Mt Olympus mantle sequence, an outcrop of heavily serpentinised peridotite that is associated with a localised gravity low and proposed to be the top of a rising serpentinite diapir. Geophysical constraints to test these hypotheses at depth are lacking. </p> <p> </p> <p>We analyse data from a two-year deployment of five broadband seismometers along with the existing permanent network to create a new earthquake catalogue for Cyprus. We use our catalogue to constrain the first formalised 1-D velocity model for the island, improving earthquake locations. Earthquake hypocentres clearly delineate a northward-dipping African slab beneath Cyprus at 20-60 km depth. The most seismically active part of the island is at 15-20 km depth beneath the southern edge of the ophiolite, approximately the expected depth to the plate interface; thrust faulting focal mechanisms here are consistent with ongoing subduction. Hypocentral depths suggest a topography of the slab top, with the shallowest depths in the centre of the island, coincident with the greatest uplift in the overlying plate, supporting hypotheses of uplift driven by subduction of the Eratosthenes Seamount. A lack of seismicity in a 20km-wide zone at this ‘peak’ coincides with the outcropping Mt Olympus mantle sequence, and may be associated with the deep root of the proposed serpentinite diapir. </p>

<p>The eastern Mediterranean hosts extensional, strike-slip, and collision tectonics above a set of fragmenting subducting slabs. Widespread Miocene-Recent volcanism and ~2km uplift has been attributed to mantle processes such as delamination, dripping and/or slab tearing/break-off. We investigate this region using broadband seismology: mantle tomographic imaging (Kounoudis et al., 2020), SKS splitting analysis of seismic anisotropy (Merry et al., 2021), and receiver function study of crustal structure (Ogden & Bastow, 2021). Anisotropy and crustal structure are more spatially variable than recognised previously, but variations correspond well with tomographically-imaged mantle structure. Moho depth correlates poorly with elevation, suggesting crustal thickness variations alone do not explain Anatolian topography: a mantle contribution, particularly in central and eastern Anatolia, is needed too. Lithospheric anisotropy beneath the North Anatolian Fault reveals a mantle shear zone deforming coherently with the surface, while backazimuthal variations in splitting parameters indicate fault-related lithospheric deformation. Anisotropic fast directions are either fault-parallel or intermediate between the principle extensional strain rate axis and fault strike, diagnostic of a relatively low-strained transcurrent mantle shear zone.</p>

<p>The island of Cyprus sits at the boundary between the Anatolian and African plates, at a transition between oceanic subduction and incipient continental collision. Seismicity has been recorded here for millenia, with at least 12 town-destroying earthquakes recorded over the last 2,000 years. However, the instrumental coverage on the island has remained poor until relatively recently, and there is no bespoke velocity model or local magnitude scale, meaning that local seismicity is relatively poorly understood. Larger earthquakes, mainly to the south and west of the island, have revealed a mix of strike-slip and reverse faulting mechanisms. More enigmatic is the onshore seismicity, and questions remain over deformation within the Cyprus slab and uplift mechanisms of the Troodos ophiolite. We investigate seismicity in and around the island, in order to better understand these processes and their associated seismic hazard. We combine records of a temporary deployment of five broadband seismometers with the 13 permanent broadband seismometers on the island, as well as two accelerometers, to create a two-year local earthquake catalogue. We locate earthquakes both within the overriding Cyprus crust and the underthrusting African plate, and identify previously unrecognised seismically active regions on the island, especially around the Troodos ophiolite. We use this earthquake catalogue to constrain a new 1-D velocity model and local magnitude scale for the region. We also constrain new focal mechanisms and interpret these in the context of the regional tectonics.</p>