Crustal Attenuation within the Turkish Plateau and Surrounding Regions

The lateral variations of seismic attenuation in the crust of Turkey and surrounding regions have been imaged from the inversion of interstation Lg Q -measurements. This study develops the first tomographic model for Lg Q 0 in this region. That model is consistent with previous more qualitative Lg -attenuation models that showed inefficient or blocked Lg across the Eurasian-Arabian plate boundary. In general, the northern Arabian platform has low to normal Lg Q 0 -values (∼250–350), whereas high Q 0 -values (∼670–800) occur in the southern Arabian Plate. Additionally, we have found a dramatic decrease in Lg Q 0 across the Bitlis suture, the plate boundary between the Arabian and Eurasian plates. Beneath the Turkish Plateau, our high to moderate Lg -attenuation values ( Q 0 ∼100–200) probably originates from both scattering and intrinsic attenuation due to the tectonic complexity and the widespread young volcanics in the region. We conclude that the lowest Q 0 -values for the East Anatolian plateau (∼70–100) and the portion of western Turkey around the Menderes Massif (∼60–150) are probably caused by intrinsic attenuation. We find low to normal Lg Q 0 -values (∼150–300) beneath the part of the Taurus Mountains in western Anatolia. These higher values may be related to the nature of the crust in the Tauride mountain belt. We also mapped the lateral variations in Lg η and observed a fairly consistent negative correlation between η and Lg Q 0 in the northern Middle East.