TELESEISMIC P-RESIDUAL STUDY IN THE IBERIAN PENINSULA

Teleseismic P-wave residuals, cleared of the effects of various source regions and deep mantle paths, reflect the composition and structure of the lithosphere and asthenosphere beneath seismological stations. W e use a method with which we compute two components of the relative re siduals for each station, namely a directionally independent average a nd azimuth-incidence angle dependent terms, and also the ACH 3-D inver sion method. The representative averages show consistent variations ov er the Iberian Peninsula with a relatively steep gradient in some area s-the Iberian Massif and the Betic Cordillera. These changes attain va lues around 1 s over a distance of about 200 km. The lateral variation s of these residual averages are transformed into a tentative model of the lithosphere thickness. A thick lithosphere is observed beneath th e Iberian Massif, the Pyrenees, and beneath part of the Betic Cordille ra. Waves from events at different teleseismic distances and various a zimuths provide consistent residual patterns and a systematic directio nal dependence of the relative residuals especially at stations in the Betic Cordillera.