A study of anisotropy beneath great britain using the polarizations of teleseismic shear-waves recorded by BGS/UKNET.

The directions of the polarizations of the leading shear-wave, recorded by the United Kingdom seismometer network (UKNET) of the British Geological Survey, have been analyzed to investigate the anisotropic structure beneath the United Kingdom. Fifty-nine short-period and seventeen long-period records from 15 intermediate and deep earthquakes, mainly from the northwestern Pacific area, were used to identify the polarization directions. The short-period shear-waves show polarization directions primarily scattered around the polarization directions of long-period (about 20 s) shear-waves. Since such long-period shear-waves can preserve the polarization directions radiated at the source fixed by the geometry and orientation of the focal mechanism, the short-period polarization directions are primarily the same as the source polarization directions. This can be interpreted as indicating that anisotropy beneath the UK, if it exists, is weak and not uniformly aligned, and is localized possibly into several blocks.