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Nearly 1500 stress orientation determinations are now available for Europe. The data come from earthquake focal mechanisms, overcoring measurements, well bore breakouts, hydraulic fracturing measurements, and young fault slip studies and sample the stress field from the surface to seismogenic depths. Three distinct regional patterns of maximum compressive horizontal stress (SHmax) orientation can be defined from these data: a consistent NW to NNW SHmax stress orientation in western Europe; a WNW‐ESE SHmax orientation in Scandinavia, similar to western Europe but with a larger variability of SHmax orientations; and a consistent E‐W SHmax orientation and N‐S extension in the Aegean Sea and western Anatolia. The different stress fields can be attributed to plate‐driving forces acting on the boundaries of the Eurasian plate, locally modified by lithospheric properties in different regions. On average, the orientation of maximum stress in western Europe is subparallel to the direction of relative plate motion between Africa and Europe and is rotated 17° clockwise from the direction of absolute plate motion. The uniformly oriented stress field in western Europe coincides with thin to medium lithospheric thickness (approximately 50–90 km) and high heat flow values (>80 m W/m2). In western Europe a predominance of strike‐slip focal mechanisms implies that the intermediate principal stress is vertical. The more irregular horizontal stress orientations in Scandinavia coincide with thick continental lithosphere (110–170 km) and low heat flow (<50 m W/m2). The cold thick lithosphere in this region may result in lower mean stresses associated with far‐field tectonic forces and allow the stress field to be more easily perturbed by local effects such as déglaciation flexure and topography. The stress field of the Aegean Sea and western Anatolia is consistent with N‐S extension in a back arc setting behind the Hellenic trench subduction zone. The stress field is influenced in places by regional geologic structures, e.g., in the Western Alps, where SHmax directions show a slight tendency toward a radial stress pattern. Not all major geologic structures, however, appear to affect the SHmax orientation, e.g., in the vicinity of the Rhine rift system horizontal stress orientations are continuous.

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S U M M A R YWe present the results of a surface wave study carried out across Greenland as part of the 'GLATIS' (Greenland Lithosphere Analysed Teleseismically on the Ice Sheet) project. Rayleigh wave phase velocity dispersion curves were estimated for 45 two-station paths across Greenland, using data from large teleseismic earthquakes. The individual dispersion curves show characteristics broadly consistent with those of continental shields worldwide, but with significant differences across the Greenland landmass. Reliable phase velocity measurements were made over a period range of 25-160 s, providing constraint on mantle structure to a depth of ∼300 km.An isotropic tomographic inversion was used to combine the phase velocity information from the dispersion curves, in order to calculate phase velocity maps for Greenland at several different periods. The greatest lateral variation in phase velocity is observed at intermediate periods (∼50-80 s), where a high-velocity anomaly is resolved beneath central-southwestern Greenland, and a low-velocity anomaly is resolved beneath southeastern Greenland.The results of the phase velocity inversion were used to construct localized dispersion curves for node points along two parallel north-south profiles in southern Greenland. These curves were inverted to obtain models of shear wave velocity structure as a function of depth, again with the assumption of isotropic structure. A similar inversion was carried out for two twostation dispersion curves in northern Greenland, where the resolution of the phase velocity maps is relatively low.The models show a high-velocity 'lid' structure overlying a zone of lower velocity, beneath which the velocity gradually increases with depth. The 'lid' structure is interpreted as the continental lithosphere. Within the lithosphere, the shear wave velocity is ∼4-12 per cent above global reference models, with the highest velocities beneath central-southwestern Greenland. However, the assumption of isotropic structure means that the maximum velocity perturbation may be overestimated by a few per cent. The lithospheric thickness varies from ∼100 km close to the southeast coast of Greenland to ∼180 km beneath central-southern Greenland.

In the computation of synthetic seismograms by modal summation, when a medium with a sharp lateral discontinuity is considered, a fundamental role is played by a coupling coefficient cj#, The coefficient r;ir is defined via an integral relation involving products between displacements and stresses and can be evaluated both numerically and analytically. The calculation of r;i. can be reduced to the analytical computation of a sum of integrals of elementary functions. The analytical method proved to be particularly convenient for its speed and precision of the results obtained.The energy redistribution within the different modes is illustrated, both in the frequency and in the time domain. Mode conversion cannot be neglected when dealing with higher modes.

Recordings of regional earthquakes near Denmark and the North Sea have been collected in an attempt to find the Lg-wave propagation properties in the area. Propagation paths of lengths between 300 and 1100 km are investigated. The amplitudes of the Lg-waves and the other seismic phases in the seismograms are compared. The propagation paths are classified according to whether the Lg-wave propagation compared t o S. Gregersm seafloor spreading separated Greenland from E,urope. The frequency-dependent propagation of the Lg-waves is explainable in terms of surface wave propagation across structural boundaries as well as in terms of anelastic attenuation.

The propagation of &-waves within the continental area in and around the North Sea basin shows strong dependence on the path between source and receiver. Paths lying within the British Isles and Norway show very clear L , phases, but paths which cross the graben zone lying in the middle of the North Sea basin have very weak L,. Over 150 paths have now been studied across the region and the character of the &-wave has been described by comparison with the size of the S, phase. For shallow events this gives a stable measure of the efficiency of L , propagation. The regions which appear to block the transmission of L , are quite localized in the middle of the North Sea, in the region with graben structures, and extend on into The Netherlands. A weak zone of poor transmission appears to be associated with the Oslo graben.With the relatively dense areal coverage provided by paths crossing the basin with a wide range of azimuths, it is possible to attempt to invert for the pattern of crustal heterogeneity which gives rise to the observed character of the t, propagation. An iterative scheme has been devised to find the propagation properties in cells of a 1" x 1' grid, and a well-defined map of the heterogeneity is obtained. The strongest heterogeneities correlate very well with the major tectonic features of the Viking and Central Grabens running northsouth through the basin. Where the path coverage is greatest, the position of the heterogeneity can be tightly constrained and lies within a rather narrow zone around 100 km wide. Despite the number of paths employed it is not possible to obtain this level of resolution over the whole region. Seen in the

An extensive data set of earthquake focal mechanisms is now available for all of northern Europe and especially for Fennoscandia. These mechanisms are considered to provide representative coverage of the stress field. The maximum horizontal compressional stress orientations are internally very consistent over the area of northern Europe. The dominating NW‐SE compressional stresses appear tied to relative plate motion, with Mid‐Atlantic Ridge spreading and European‐African collision in southern Europe. For Fennoscandia some exceptions to the regional stress pattern exist. The causes of these local anomalies have been investigated. No correlations with geological provinces or province boundaries were found. In addition, there does not appear to be any clear correlation between anomalous stress directions and postglacial uplift in the present earthquake activity. This lack of correlation is in sharp contrast to geological evidence in the form of large faults indicative of large postglacial earthquakes occurring right after the end of the latest ice age, 9000 years ago. Taken together, this evidence suggests a tremendous change of stress field in Holocene time, from one dominated by the postglacial unloading right after the ice age to one dominated by the present plate motion today.