Morphotectonics of the Iberian Peninsula

A morphotectonic interpretation of the relief of the Iberian Peninsula (IP) is presented based on an analysis of its gross forms. Several geological–geophysical and geomorphological methods were used in order to build up a morphostructural sketch. Three main categories were established using the approach of RANTSMAN (1979): Territorial Units (1-megablock, 9-macroblocks, 34-mesoblocks, 1.374- blocks and 2.523-microblocks); Morphostructural Alignments (2-first, 8-second, 20-third and 1-fourth rank; and 43 knots between Morphostructural Alignments (second-fourth rank). The main seismic activity is concentrated on the first- and second-rank lineaments, and some important epicenters are located near the lineament intersections. The origin of the earthquakes in the vicinity of such knots can be explained by the forcing/pushing of macroblocks westwards. The existence of earthquakes along the lineaments may be explained by tension. From the present study it appears that earthquake occurrence in the IP is due principally to stress concentrations around morphotectonic zones. A seismotectonic interpretation of the IP is also presented. On this map three zones are distinguished (A, B, C), each of them with a different active level and dimensions.