Lg wave attenuation tomography in the Chinese mainland
We present a tomographic attenuation model using crustal Lg waveform data recorded by permanent broadband seismic stations from 2009 t0 2019 in the Chinese mainland.We derive 360000 inter-station Lg wave Q values by employing the Reverse Two Station method.Our crustal attenuation model reveals significant lateral variations across the Chinese mainland.The variation of crustal Lg wave attenuation strongly correlates with regional tectonic activity and crustal properties,including the thickness of unconsolidated sediments,the presence of aqueous fluids,and partial melt content.Regions like the Tibetan Plateau,Bohai Bay Basin and Qilian Mountain exhibit strong attenuation marked by low crustal Q values.In contrast,stable blocks such as the South China Block,Ordos Basin,and Tarim Basin demonstrate weak attenuation,denoted by high crustal Q values.The strong attenuation obsetved in the Bohai Bay Basin primarily results from the presence of thick unconsolidated sediments coupled with elevated crustal temperatures.The predominant factors contributing to strong attenuation in regions such as the Tibetan Plateau and Qilian Mountain are active tectonic activities,fractured fragments,widespread crustal fluids,and even partial melt.The low crustal attenuation in the South China tectonic block and the Great Xing'an Range may be due to the formation of a high-strength crustal basement from the cooling and crystallization of intrusive rocks,as well as the stabilization of crustal structures in the ancient orogenic belt.
万方数据
维普
