Imágenes de velocidad sísmica en la regón inferior del manto litosférico de la Península Ibérica

Abstract

Travel times of 46,700 Pn arrivals collected from 3,000 earthquakes are inverted to image the lower lid seismic velocities beneath the Iberian Peninsula and surrounding regions. The results show an average uppermost mantle velocity beneath the study area of 8.26 km/s, ranging from 7.96 km/s to 8.56 km/s, which confirms the positive velocity gradient for the upper mantle of this region. The peninsular area covered by the Iberian massif is characterized by high Pn velocities, as expected in tectonically stable regions, indicating areas of the Hercynian belt that have not recently been reactivated. The tomography shows that fast lower lid velocities are present also below a large part of the Betic Cordilleras, where the upper lid is characterized by a pronouncedly low Pn velocity, as is common in areas greatly affected by recent tectonic and magmatic activity. Our model indicates that the deepest Betic crustal root might be underlied by a positive anomaly beneath the southeastern Iberian Peninsula.