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The Arabia‐Eurasia collision deforms an area of ∼3,000,000 km2 of continental crust, making it one of the largest regions of convergent deformation on Earth. There are now estimates for the active slip rates, total convergence and timing of collision‐related deformation of regions from western Turkey to eastern Iran. This paper shows that extrapolating the present day slip rates of many active fault systems for ∼3–7 million years accounts for their total displacement. This result means that the present kinematics of the Arabia‐Eurasia collision are unlikely be the same as at its start, which was probably in the early Miocene (16–23 Ma) or earlier. In some, but not all, active fault systems, short‐term (∼10 year) and long‐term (∼5 million year) average deformation rates are consistent. There is little active thickening across the Turkish‐Iranian plateau and, possibly, the interior of the Greater Caucasus. These are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening, and where there are structural and/or stratigraphic data for pre‐late Miocene deformation. We suggest that once thick crust (up to 60 km) built up in the Turkish‐Iranian plateau and the Greater Caucasus, convergence took place more easily by crustal shortening in less elevated regions, such as the Zagros Simple Folded Zone, the South Caspian region and foothills of the Greater Caucasus, or in other ways, such as westward transport of Turkey between the North and East Anatolian faults. The time and duration of this changeover are not known for certain and are likely be diachronous, although deformation started or intensified in many of the currently active fault systems at ∼5 ± 2 Ma.

SUMMAR YWe use observations of surface faulting, well-constrained earthquake focal mechanisms and centroid depths, and velocity structure determined by surface wave propagation and teleseismic receiver functions to investigate the present-day deformation and kinematics in and around the South Caspian Basin. The lack of earthquakes within the basin itself indicates that it behaves as a rigid block, though its sedimentary cover is deformed by numerous folds that are decoupled from its rigid basement by overpressured mud. The basin contains a sedimentary sequence almost 20 km thick above a relatively highvelocity basement that is thinner within the basin than on its margins. The basement beneath the basin could be either unusually thick oceanic crust or thinned, but relatively high-velocity, continental crust. The South Caspian Basin is surrounded by active earthquake belts on all sides. No earthquakes deeper than 30 km can be confirmed in the Kopeh Dag, Alborz and Talesh, which bound the NE, S and W sides of the basin. In contrast, earthquakes occur to depths of at least 80 km on the Apsheron-Balkhan sill, which bounds the N side of the basin and where no earthquakes can be confirmed that are shallower than 30 km. We interpret these deeper earthquakes to indicate the onset of subduction of the South Caspian Basin beneath the central Caspian, a process that appears to occur aseismically at shallow levels. Although oblique shortening is partitioned into pure strike-slip and pure thrust in many areas, conjugate right-lateral and leftlateral components in the Kopeh Dag and eastern Alborz suggest that the South Caspian Basin has a westward component of motion relative to both Eurasia and Iran. This motion enhances westward underthrusting of the basin beneath the Talesh mountains of Iran and Azerbaijan. We estimate the present motions of the South Caspian Basin to be y13-17 mm yr x1 to the SW relative to Iran (a maximum value) and y8-10 mm yr x1 to the NW or NNW relative to Eurasia. We suspect that these motions are all relatively recent, and may have begun only in the Pliocene (3-5 Ma). The South Caspian Basin will ultimately be destroyed by subduction or underthrusting and its present situation may represent an intermediate stage between that of the eastern Mediterranean and that of the seismically active slab beneath the Hindu Kush.

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SUMMARY We use observations of surface faulting, well‐constrained earthquake focal mechanisms and centroid depths, and velocity structure determined by surface wave propagation and teleseismic receiver functions to investigate the present‐day deformation and kinematics in and around the South Caspian Basin. The lack of earthquakes within the basin itself indicates that it behaves as a rigid block, though its sedimentary cover is deformed by numerous folds that are decoupled from its rigid basement by overpressured mud. The basin contains a sedimentary sequence almost 20 km thick above a relatively high‐velocity basement that is thinner within the basin than on its margins. The basement beneath the basin could be either unusually thick oceanic crust or thinned, but relatively high‐velocity, continental crust. The South Caspian Basin is surrounded by active earthquake belts on all sides. No earthquakes deeper than 30 km can be confirmed in the Kopeh Dag, Alborz and Talesh, which bound the NE, S and W sides of the basin. In contrast, earthquakes occur to depths of at least 80 km on the Apsheron–Balkhan sill, which bounds the N side of the basin and where no earthquakes can be confirmed that are shallower than 30 km. We interpret these deeper earthquakes to indicate the onset of subduction of the South Caspian Basin beneath the central Caspian, a process that appears to occur aseismically at shallow levels. Although oblique shortening is partitioned into pure strike‐slip and pure thrust in many areas, conjugate right‐lateral and left‐lateral components in the Kopeh Dag and eastern Alborz suggest that the South Caspian Basin has a westward component of motion relative to both Eurasia and Iran. This motion enhances westward underthrusting of the basin beneath the Talesh mountains of Iran and Azerbaijan. We estimate the present motions of the South Caspian Basin to be ∼ 13–17 mm yr−1 to the SW relative to Iran (a maximum value) and ∼ 8–10 mm yr−1 to the NW or NNW relative to Eurasia. We suspect that these motions are all relatively recent, and may have begun only in the Pliocene (3–5 Ma). The South Caspian Basin will ultimately be destroyed by subduction or underthrusting and its present situation may represent an intermediate stage between that of the eastern Mediterranean and that of the seismically active slab beneath the Hindu Kush.

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