P-wave attenuation variations beneath the central and western Tien Shan from teleseismic waves

Abstract

The seismic attenuation plays an important role in understanding the subsurface structure and provides complementary information on the mantle dynamic together with seismic velocity information. Here we explore the attenuation structure beneath the central and western Tien Shan using teleseismic P-wave data. Firstly, we map the spatial distribution of relative attenuation parameter using the spectral ratio technique in the frequency band between 0.1 and 1.5 Hz. Our results reveal strong lateral attenuation variations in the lithosphere and asthenosphere underneath the study area. Then we invert for the Q_p values using a linear inversion approach. Two high-attenuation regions are observed beneath the middle Tien Shan and western Tarim Basin that could be associated with upwelling hot materials and/or a small plume. Moreover, low-attenuation regions are found beneath the Kazakh Shield and western Tien Shan, which can be attributed to the underthrusted/subducted lithospheric fragments.