利用区域地震记录测定地震辐射能量  

The determination of radiated seismic energy of earthquakes based on regional seismic records

作　　者：王子博 刘瑞丰[1] 李赞 孔韩东 胡岩松 WANG ZiBo;LIU RuiFeng;LI Zan;KONG HanDong;HU YanSong(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]中国地震局地球物理研究所,北京100081

出　　处：《地球物理学报》2023年第2期626-637,共12页Chinese Journal of Geophysics

基　　金：中国地震局地球物理研究所基本科研业务专项(DQJB22B18;DQJB21X28)共同资助。

摘　　要：地震辐射能量作为描述地震大小的物理量,可为地震应急和灾害评估提供重要参考.现有快速测定地震辐射能量的方法多使用远震记录(35°≤Δ<80°),受到几何扩展和频率相关衰减校正方法的限制,利用区域地震记录(5°≤Δ<35°)测定地震辐射能量的难度较大.因此,本文发展了一种利用区域地震记录快速测定地震辐射能量的方法.研究结果表明:(1)利用该方法可以测定5.0级以上地震的辐射能量,弥补了由于低信噪比和台站分布影响,导致利用远震记录只能稳定测定6.0级以上地震辐射能量的不足;(2)将该方法应用于2009-2021年发生在中国大陆的66次MW>5.0地震,结果显示74%的单台区域能量震级与远震能量震级的偏差在±0.3以内;对于44次MW≥5.5地震,区域结果与远震结果基本一致,86%的事件区域能量震级与远震能量震级的差在±0.2之间;(3)结合地震矩资料,得到中国大陆地区地震的能矩比范围为5.2×10^(-6)~8.1×10^(-5),平均能矩比为2.4×10^(-5);走滑型地震的平均能矩比高于倾滑型地震,能矩比整体分布存在区域特征,西域地块地震的平均能矩比高于青藏地块东部地震,青藏地块西部地震的平均能矩比最低,同一区域内的地震能矩比也存在差别,这表明不同断层上发生的地震能量释放过程存在明显差异;(4)该方法具有广泛的应用前景,可以在地震台网的日常工作中测定地震辐射能量,为科学研究、地震应急和地震灾害评估提供新的地震参数.As a physical quantity describing the size of an earthquake, radiated seismic energy can provide an important reference for earthquake emergency and disaster assessment. Previously published methods to determine the radiated seismic energy often use broadband teleseismic records(35°≤Δ<80°). However, constrained by the correction for geometrical spreading and frequency-dependent attenuation, the determination of radiated seismic energy is more different for waveforms recorded at or near regional distances(5°≤Δ<35°). In this paper, we generalize a method for energy estimation from teleseismic broadband records to the regional broadband waveform. The result can be concluded that:(1) We can obtain the radiated seismic energy of earthquakes above MW5.0 using this method, which makes up for the shortcomings that using teleseismic records can only stably determine the radiated seismic energy of earthquakes above MW6.0 due to the influence of low signal-to-noise ratio and station distribution;(2) Applying this method to 66 earthquakes above MW5.0 occurred in China's Mainland between 2009 and 2021, the results show that the difference between corrected regional energy magnitude of a single station and the event can be controlled within 0.3 for 74% of the records;for 44 earthquakes with MW≥5.5, the average estimate of radiated seismic energy from regional data is nearly the same as that obtained from the teleseismic data, and the difference between corrected regional and teleseismic energy magnitude can be controlled within 0.2 for 86% of the events;(3) Combined with seismic moment data, we investigate the characteristics of energy-to-moment ratio in China's Mainland. It can be concluded that the average energy-to-moment ratio is 2.4×10^(-5)(range, 5.2×10^(-6)~8.1×10^(-5)), the average energy-to-moment ratio of strike-slip earthquakes is higher than that of dip-slip earthquakes. The distribution of energy-to-moment ratio has an overall regional characteristic. The average energy-to-moment ratio of earthquake

关 键 词：地震辐射能量 能矩比 区域地震记录 远震记录 中国大陆 

分 类 号：P315[天文地球—地震学]