We provide a present-day surface-kinematics model for the Alpine region and surroundings based on a high-level data analysis of about 300 geodetic stations continuously operating over more than 12 years. This model includes a deformation model, a continuous surface-kinematic (velocity) field, and a strain field consistently assessed for the entire Alpine mountain belt. Special care is given to the use of the newest Global Navigation Satellite Systems (GNSS) processing standards to determine high-precision 3-D station coordinates. The coordinate solution refers to the reference frame IGb08, epoch 2010.0. The mean precision of the station positions at the reference epoch is ±1.1 mm in N and E and ±2.3 mm in height. The mean precision of the station velocities is ±0.2 mm a⁻¹ in N and E and ±0.4 mm a⁻¹ in height. The deformation model is derived from the point-wise station velocities using a geodetic least-squares collocation (LSC) approach with empirically determined covariance functions. According to our results, no significant horizontal deformation is detected in the Western Alps, while across the Southern and Eastern Alps the deformation vectors describe a progressive eastward rotation towards Pannonia. This kinematic pattern also makes evident an increasing magnitude of the deformation from 0.1 mm a⁻¹ in the western part of Switzerland up to about 1.3 mm a⁻¹ in the Austrian Alps. The largest shortening is observed along the southern front of the Eastern Alps (in the northern area of the Venetian-Friuli Basin) and in the northern part of the Apennine Peninsula, where rates reach 2 and 3 mm a⁻¹, respectively. The average accuracy of the horizontal deformation model is ±0.2 mm a⁻¹. Regarding the vertical kinematics, our results clearly show an ongoing average uplift rate of 1.8 mm a⁻¹ of the entire mountain chain, with the exception of the southern part of the Western Alps, where no significant uplift (less than 0.5 mm a⁻¹) is detected. The fastest uplift rates (more than 2 mm a⁻¹) occur in the central area of the Western Alps, in the Swiss Alps, and in the Southern Alps in the boundary region between Switzerland, Austria, and Italy. The general uplift observed across the Alpine mountain chain decreases towards the outer regions to stable values between 0.0 and 0.5 mm a⁻¹ and, in some cases, to subsidence like in the Liguro-Provençal and Vienna basins, where vertical rates of −0.8 and −0.3 mm a⁻¹ are observed, respectively. In the surrounding region, three regional subsidence regimes are identified: the Rhône-Bresse Graben with −0.8 mm a⁻¹, the Rhine Graben with −1.3 mm a⁻¹, and the Venetian-Friuli Basin with −1.5 mm a⁻¹. The estimated uncertainty of our vertical motion model across the Alpine mountain belt is about ±0.3 mm a⁻¹. The strain field inferred from the deformation model shows two main contrasting strain regimes: (i) shortening across the south-eastern front of the Alps and the northern part of the Dinarides and (ii) extension in the Apennines. The pattern of the principal strain axes indicates that the compression directions are more or less perpendicular to the thrust belt fronts, reaching maximum values of 20×10⁻⁹ a⁻¹ in the Venetian-Friuli and Po basins. Across the Alpine mountain belt, we observe a slight dilatation regime in the Western Alps, which smoothly changes to a contraction regime in western Austria and southern Germany, reaching maximum shortening values of 6×10⁻⁹ a⁻¹ in north-eastern Austria. The numerical results of this study are available at https://doi.pangaea.de/10.1594/PANGAEA.886889.

In 2004, first absolute gravity (AG) measurements were performed on the top of Mt. Zugspitze (2 sites) and at the foot (1 site) and top (1 site) of Mt. Wank. Mt. Wank (summit height 1780 m) and Mt. Zugspitze (2960 m) are about 15 km apart from each other and belong geologically to different parts of the Northern Limestone Alps. Bridging a time span of 15 years, the deduced gravity variations for Zugspitze are in the order of −0.30 μm/s² with a standard uncertainty of 0.04 μm/s². The Wank stations (foot and top) show no significant gravity variation. The vertical stability of Wank summit is also confirmed by results of continuous GNSS recordings. Because an Alpine mountain uplift of 1 or 2 mm/yr cannot explain the obtained gravity decline at Zugspitze, the dominating geophysical contributions are assumed to be due to the diminishing glaciers in the vicinity. The modelled gravity trend caused by glacier retreat between epochs 1999 and 2018 amounts to −0.012 μm/s²/yr at both Zugspitze AG sites. This explains more than half of the observed gravity decrease. Long-term variations on inter-annual and climate-relevant decadal scale will be investigated in the future using as supplement superconducting gravimetry (installed in 2019) and GNSS equipment (since 2018).

In 2004, first absolute gravity (AG) measurements were performed on the mountain tops of Mt. Zugspitze (2 sites) and Mt. Wank (1 site), and at the Wank foot (1 site). Wank (summit height 1780 m) and Zugspitze (2960 m) are about 20 km apart from each other and belong geologically to different parts of the Northern Limestone Alps. Bridging a time span of 15 years, the deduced gravity variations for Zugspitze are in the order of 0.30 μm/s² with a standard uncertainty of 0.04 μm/s². The Wank stations (foot and top) show no significant gravity variation. The vertical stability of Wank summit is also confirmed by results of continuous GNSS recordings. Because an Alpine mountain uplift of 1 or 2 mm/yr cannot explain the obtained gravity decline at Zugspitze, the dominating geophysical contributions are assumed to be due to the diminishing glaciers in the vicinity. The modelled gravity trend caused by glacier retreat between epochs 1999 and 2018 amounts to -0.012 μm/s²/yr at both Zugspitze AG sites. This explains more than half of the observed gravity decrease. Long-term variations on inter-annual and climate-relevant decadal scale will be investigated in the future using as a supplement superconducting gravimetry (installed in 2019) and GNSS equipment (since 2018).

We provide a present-day surface-kinematics model for the Alpine region and surroundings based on a high-level data analysis of about 300 geodetic stations continuously operating over more than 12 years. This model includes a deformation model, a continuous surface-kinematic (velocity) field, and a strain field consistently assessed for the entire Alpine mountain belt. Special care is given to the use of the newest GNSS processing standards to determine high-precise 3D station coordinates. The coordinate solution refers to the reference frame IGb08, epoch 2010.0. The mean precision of the station positions at the reference epoch is ±1.1 mm in N and E and ±2.3 mm in height. The mean precision of the station velocities is ±0.2 mm/a in N and E and ±0.4 mm/a in the height. The deformation model is derived from the pointwise station velocities using a geodetic least-squares collocation approach with empirically determined covariance functions. According to our results, no significant horizontal deformation is detected in the Western Alps, while across the Southern and Eastern Alps the deformation vectors describe a progressive eastward rotation toward Pannonia. This kinematic pattern makes also evident an increasing magnitude of the deformation from 0.1 mm/a in the western part of Switzerland up to about 1.5 mm/a in the Austrian Alps. The largest shortenings are observed along the southern front of the Eastern Alps (in the northern area of the Venetian-Friuli Basin) and in the northern part of the Apennine Peninsula, where they reach 2 mm/a and 3 mm/a, respectively. The averaged accuracy of the horizontal deformation model is ±0.2 mm/a. Regarding the vertical kinematics, our results clearly show an still on-going averaged uplift of 1.8 mm/a of the entire mountain chain, with exception of the southern part of the Western Alps, where no significant uplift (less than 0.5 mm/a) is detected. The fastest uplift rates (more than 2 mm/a) occur in the central area of the Western Alps, in the Swiss Alps and in the Southern Alps in the boundary region between Switzerland, Austria and Italy. The general uplift observed across the Alpine mountain chain decreases toward the outer regions to stable values between 0.0 and 0.5 mm/a and, in some cases, to subsidence like in the Liguro-Provençal and Vienna Basins, where vertical rates of −0.8 mm/a and −0.3 mm/a are observed respectively. In the surroundings, three regional subsidence regimes are identified: the Rhone-Bresse Graben with −0.8 mm/a, the Rhine Graben with −1.3 mm/a, and the Venetian-Friuli Basin with −1.5 mm/a. The estimated uncertainty of our vertical motion model across the Alpine mountain belt is about ±0.3 mm/a. The strain field inferred from the deformation model shows two main contrasting strain regimes: shortening across the south-eastern front of the Alps and the northern part of the Dinarides, and extension in the Apennines. The pattern of the strain principal axes indicates that the compression directions are more or less perpendicular to the thrust belt fronts, reaching maximum values of 20 x 10⁻⁹ a⁻¹ in the Venetian-Friuli and Po Basins. Across the Alpine mountain belt, we observe a slight dilatation regime in the Western Alps, which smoothly changes to a contraction regime in West Austria and South Germany, reaching maximum shortening values of 6 x 10⁻⁹ a⁻¹ in the north-eastern Austria. The numerical results of this study are available at https://doi.pangaea.de/10.1594/PANGAEA.886889.

For this study we collected the data of more than 200 continuously operating geodetic GNSS stations (GNSS: Global Navigation Satellite System) from Italy, France, Switzerland, Germany, Austria and several stations from surrounding countries. We processed all available GPS and GLONASS data between 2004 and 2016 in order to derive precise station positions and velocities. The newest processing standards were applied in order to determine 3-D coordinates with highest precision in the IGb08, epoch 2010.0, which was the relevant realization of the International Terrestrial Reference System (ITRS) at the time of processing the data. The mean precision of the station velocities is ±0.2 mm/a for the North and East component, while the precision for vertical velocity is determined to be ±0.4 mm/a. In a second step, we derived deformation models for the Alpine mountain belt based on the estimated surface velocities. It consists of a horizontal and a vertical deformation model, which were derived based on the least-squares collocation (LSC) method. These kinematic models are purely numerical and no information or condition regarding the structure of the lithosphere has been considered in advance. However, to get a homogeneous data coverage in the Central Alps, we included IGb08-based station velocities of the Automated GNSS Network for Switzerland (AGNES). According to our results, the largest horizontal deformation of 2 mm/a occurs in the Friuli region, while it is practically insignificant in the Western Alps. The vertical deformation model shows an on-going average uplift of 1.8 mm/a for the entire mountain chain, with the exception of the southern part of the Western Alps, where no significant uplift is visible. The largest rates of up to 2.6 mm/a are observed in the central area of the Western Alps, in the Swiss Alps and the Southern Alps in the boundary region between Switzerland, Austria and Italy.