Jm. Nocquet et al., Intraplate deformation in western Europe deduced from an analysis of the International Terrestrial Reference Frame 1997 (ITRF97) velocity field, J GEO R-SOL, 106(B6), 2001, pp. 11239-11257
Although tectonic deformation in western Europe is essentially concentrated
in the Appenines and Alpine (Alps, Pyrenees) mountain ranges, several larg
e historical and instrumentally recorded earthquakes (M >6) are known in th
e supposedly "stable" part of Europe. Because of its accuracy and internal
consistency at a global scale, the International Terrestrial Reference Fram
e 1997 (ITRF97) velocity field allows testing of intraplate rigidity in wes
tern Europe at a millimeter per year level. Using the full statistical info
rmation available on the ITRF97 velocities, we identify a subset of sites l
ocated in central Europe that satisfies a rigid cap rotation with residual
velocities <1 mm/yr and therefore provide a stable europe reference frame (
SERF). In this reference frame we find residual velocities at European ITRF
sites that are consistent with known active tectonic features. We identify
a northward motion at. sites located in Italy, with internal deformation o
f the Adriatic block rather than rigid plate motion and a westward motion o
f the westernmost part of Europe of the order of 1-2 mm/yr relative to cent
ral Europe. The relative motion of the Adriatic block and western Europe ag
rees with the current extension known in the Tyrrhenian sea and the Apennin
es, III central Europe, we find active deformation <1 mm/yr in the eastern
Alps and western Carpathians. In the Alpine range our results indicate E-W
extension across the western Alps and N-S compression across the central an
d eastern Alps, in agreement with the strain regime deduced from seismotect
onic observations, In Belgium and the Netherlands we find residual velociti
es of 1-1.5 mm/yr to the northwest at all the sites, most likely accommodat
ed along the Upper and Lower Rhine Graben structures. An important outcome
of this study is the identification of internal deformation of the order of
1-2 mm/yr in an area usually interpreted as "stable" Europe. This result s
hould be further checked as new, denser, and more accurate space geodetic d
ata sets with longer observation time spans, become available for Europe.