中国大陆Lg波衰减成像  

Lg wave attenuation tomography in the Chinese mainland

作　　者：何静 吴庆举[3] HE Jing;WU QingJu(National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;Key Laboratory of Compound and Chained Natural Hazards Dynamics,Ministry of Emergency Management of China,Beijing 100085,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]应急管理部国家自然灾害防治研究院,北京100085 [2]复合链生自然灾害动力学应急管理部重点实验室,北京100085 [3]中国地震局地球物理研究所,北京100081

出　　处：《地球物理学报》2024年第3期889-899,共11页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42074102,41704054);应急管理部国家自然灾害防治研究院中央级公益性科研院所基本科研业务专项(ZDJ2020-11)资助。

摘　　要：本文利用2009-2019年间中国大陆固定台站记录的宽频带地震波形数据,采用反双台法,获得了约36万个台站对的Lg波Q值,并反演得到了中国大陆Lg波的衰减模型.结果显示,中国大陆Lg波衰减的Q值结构存在显著的横向非均一性.青藏高原、渤海湾盆地以及祁连山造山带等构造活动块体展现出明显的地壳低Q值强衰减特征,而华南块体、鄂尔多斯盆地以及塔里木盆地等相对稳定的地区则呈现地壳高Q值弱衰减特征.Lg波衰减与构造活动强度、松散沉积物、地下流体或部分熔融以及地质块体结构等因素密切相关.渤海湾盆地的强衰减主要由上地壳巨厚的松散沉积物和较高的地壳温度导致.青藏高原和祁连山造山带的地壳强衰减主要归因于现今活跃的构造活动、复杂的断裂系统和地质结构以及富含地下流体甚至是部分熔融等因素.华南造山带和大兴安岭地区的地壳弱衰减特征可能与侵入岩冷却形成高强度的结晶基底以及古老造山带地壳构造趋于稳定相关.We present a tomographic attenuation model using crustal Lg waveform data recorded by permanent broadband seismic stations from 2009 to 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 observed 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.

关 键 词：LG波 Q值 地壳衰减 中国大陆 

分 类 号：P315[天文地球—地震学]