Abstract

Lateral variations of crustal seismic attenuation across the Iberian Peninsula were estimated by means of an inversion technique applied to 1 Hz Lg  Q(Q0) measurements obtained using the two‐station method. Seismic data for this study consisted of 59 events with magnitudes 3≤mbLg≤5.4, focal depths less than 30 km, and epicentral distances from 100 to 1000 km, which were recorded by 343 seismic stations between January 2008 and October 2013. Lg‐wave propagation was found to be inefficient or blocked for most of the paths crossing the Mediterranean Sea, the western Alborán Sea, and the Strait of Gibraltar. Spectral ratios collected over 2480 high‐quality interstation paths were used to determine Lg  Q0 and its frequency dependence (η). Lg  Q0 estimates range from ∼75 to ∼800. The lateral variations of Lg  Q0 correlate well with the major tectonic features of the region and heat flow measurements. The lowest values are found in the Pyrenean range and in eastern and southern Iberia, whereas high Lg  Q0 values (i.e., lower attenuation) characterize the more stable western part of the Iberian Peninsula. The obtained results are also in agreement with previous studies in the area.

Online Material: Tables of seismic station locations, earthquake parameters, and velocity model, and figures of two‐station paths, parameter regression, site amplification analysis at E101, and lateral variation of Lg  Q0.

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