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Entering the terminal phase of continental collision, the European Alps exhibit surface deformation rates at the mm-level. Uplift peaks in the Central Alps at 2-3 mm/yr as a result of the post-glacial isostatic rebound, slab tearing, and erosion. Horizontal rate changes of w6.5 Friuli earthquake in 1975. Further north and beyond the ESE-trending, dextral Periadriatic fault, the Eastern Alps extrude into the Pannonian basin. Today’s fault slip rates are constrained by Global Navigation Satellite System (GNSS) data with an inter-station distance too sparse to provide a detailed insight into plate locking—a vital component of estimating the fault’s seismic potential.We present 4D-deformation data of the SE-Alps in unprecedented resolution (~400 m, 6 days). The rate maps were derived from radar-interferometric time-series collected since 2017 by the European Sentinel-1 satellites. Each of the assembled 240-km-wide radar tiles consists of 300+ images. The interferograms were automatically generated, phase-unwrapped, and corrected for atmospheric and topographic signal contributions. We estimated the deformation rates using the LiCSBAS time-series analysis software that involves a small-baseline approach and accounts for spatio-temporal coherence and seasonality. By tying the individual, relative InSAR rates—observed in two look directions—into a Eurasian reference frame based on by published GNSS rates we decompose them into east and vertical rates.Our results illuminate the extreme, to which we can push the InSAR signal-detection threshold if the signal-backscatter properties are as challenging as in the vegetated SE-Alps: The predominant, vertical rates result from a mixture of isostatic, tectonic and anthropogenic processes, overlaid by a soil-moisture bias; the horizontal shortening rates align northwards, to which the radar satellites is least sensitive. Nevertheless, our rates provide new, dense deformation data and highlight processes yet undetected by the GNSS monitoring network.

At the northwestern tip of the India-Asia collision zone, the north-advancing Pamir orocline overrides the Tajik-Tarim Basin along a low-angle décollement with N–S shortening rates of 10-15 mm/yr. The Pamir’s advance is buttressed in the North by the Tian Shan. Westward collapse of Pamir crust into the Tajik basin leads to overall E–W shortening in the ~N-trending Tajik fold-thrust-belt. Crustal seismicity highlights fault systems at the northern rim of the Pamir and, since the 2017 Mw7.2 Sarez earthquake, the Sarez-Karakul fault system that separates the western from the eastern Pamir as a surface expression of the northwestern tip of the underthrusting Indian cratonic mantle lithosphere. Towards southwest, the Pamir connects to the rarely sampled Hindu Kush with sparse crustal but abundant intermediate-depth seismicity; the latter is an effect on an ongoing slab break-off.We recorded displacements along the most active structures creating the recent regional deformation field by multiple satellite-geodetic observations. Up to 4.5-yr-long radar-interferometric time-series (InSAR) provide E–W and vertical surface deformation fields in unprecedented spatio-temporal resolution of 400 m and 12-24 days. The relative InSAR rate maps were tied to and complemented with accurate rates derived from Global Navigation Satellite System (GNSS) data. We collected these data in continuous and survey mode along—sometimes km-spaced—profiles across the most active faults in the region.We confirm the high interseismic strain localization along the Pamir’s northern thrust front and an increased dextral component towards the northwestern edge of the thrust belt of >8 mm/yr, accommodating the westward collapse of the orocline. The sinistral Sarez earthquake at 120-170 km distance from the front activated the basal décollement, as suggested by mm-to-cm-scale, sharp surface offsets along the whole frontal segment. Relocking occurred gradually in the following four years. Similar co-seismic offsets were observed along the sinistral, NE-trending Darvaz fault, separating the western Pamir from the Tajik basin. The Tajik fold-thrust-belt exhibits ~10 mm/yr of internal E–W shortening, in agreement with fossil shortening rates of 12-8 mm/yr since ~12 Ma. The majority of the deformation is accommodated by the Babadag backthrust (~6 mm/yr)—a major thrust located far west in the belt, and the sinistral Ilyak fault (~6 mm/yr) that bounds the belt to the North. The belt also hosts spectacular horizontal spreading rates of ≤350 mm/yr at the Hoja Mumin salt fountain. Along the most prominent fault of the Hindu Kush, the Panjsheer fault, a fault-perpendicular GNSS profile observed sinistral slip of >1-4 mm/yr. The fault is probably only locked in the upper ~km as suggested by a sharp, InSAR line-of-sight rate increase of ~6 mm/yr across the fault. This could explain the absence of shallow seismicity in the region.

Break-off of part of the down-going plate during continental collision occurs due to tensile stresses built-up between the deep and shallow slab, for which buoyancy is increased because of continental-crust subduction. Break-off governs the subsequent orogenic evolution but real-time observations are rare as it happens over geologically short times. Here we present a finite-frequency tomography, based on jointly inverted local and remote earthquakes, for the Hindu Kush in Afghanistan, where slab break-off is ongoing. We interpret our results as crustal subduction on top of a northwards-subducting Indian lithospheric slab, whose penetration depth increases along-strike while thinning and steepening. This implies that break-off is propagating laterally and that the highest lithospheric stretching rates occur during the final pinching-off. In the Hindu Kush crust, earthquakes and geodetic data show a transition from focused to distributed deformation, which we relate to a variable degree of crust-mantle coupling presumably associated with break-off at depth., Here, the authors document active slab break-off and the crustal response during continental collision under the Hindu Kush, a rarely observed process since it happens over geologically short time spans.