LITHOSPHERIC DEFORMATION INFERRED FROM TELESEISMIC SHEAR-WAVE SPLITTING OBSERVATIONS IN THE UNITED-KINGDOM

Observations of splitting in teleseismic shear waves recorded at stations in the United Kingdom (UK) seismic network operated by the British Geological Survey are related to the tectonic structures and history in the UK. The combination of network density and tectonic variability in the UK permits an assessment to be made of the relationship between splitting and geology. Fast polarization directions are most commonly parallel to geologic features resulting from compressional or strike-slip events, and splitting delay times mirror the increasing involvement of basement in deformation as observed through field investigation. Different orogenic episodes may be distinguished in the splitting orientations; A peak in delay times is suggested in the observations at the Iapetus Suture, a site of Paleozoic subduction now in the UK interior. These observations are consistent with the idea that continental anisotropy arises through coherent deformation of the lithosphere and is preserved long after orogenic deformation ceases.