基于地震学的天山地区地震动衰减关系研究  

Seismology-based ground motion attenuation relationship in the Tianshan area

作　　者：李文倩[1] 冉慧敏[1] 赵瑞胜[1,2] LI Wenqian;RAN Huimin;ZHAO Ruisheng(Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830000,Xinjiang,China;Kashi Earthquake Monitoring Center,Earthquake Agency of Xinjiang Uygur Autonomous Region,Kashi 844000,Xinjiang,China)

机构地区：[1]新疆维吾尔自治区地震局,新疆乌鲁木齐830000 [2]新疆维吾尔自治区地震局喀什地震监测中心站,新疆喀什844000

出　　处：《地震工程学报》2024年第2期449-456,464,共9页China Earthquake Engineering Journal

基　　金：中国地震局监测、预报、科研三结合课题(3JH-202302079);中国地震局地震科技星火计划(XH20068Y)。

摘　　要：选取天山地区3171条矩震级为3.5~4.5级测震记录,通过计算S波段速度傅里叶幅值谱,采用微遗传算法,反演得到5个区域地壳介质参数,即应力降Δσ为18.206 MPa,品质因子参数Q 0为444.20,η值为0.35,几何衰减参数R 1和R 2分别为74.30 km和106.59 km。根据地壳介质参数计算加速度傅氏谱,再配合随机相位谱,得到某一震级、震中距下地震动时程,提取其PGA,建立区域地震动峰值加速度衰减关系。研究结果显示,矩震级为5级和6级中远场地震动衰减关系与强震动记录符合较好,尤其是5级结果,在选取的5条经验值衰减关系中,其均值和标准差均为最小,结果最优;矩震级为7级的地震动衰减关系,远场结果高于大多数强震动记录。A total of 3171 seismic records with moment magnitude of 3.5-4.5 collected from the Tianshan area were selected in this paper.Using the microgenetic algorithm and by calculating the Fourier amplitude spectrum of the S-wave velocity,five regional crustal medium parameters were obtained:the stress dropΔσwas 182.06 bar,the quality factor parameter Q 0 was 444.20,theηvalue was 0.35,and the geometric attenuation parameters R 1 and R 2 were 74.30 and 106.59 km,respectively.Based on the five parameters,the Fourier spectrum of acceleration was calculated.Combined with the random phase spectrum,the time history of ground motion with a certain magnitude and epicentral distance was also obtained.Then,the peak acceleration attenuation relationship of regional ground motion was established.Results show that the attenuation relations of far-field ground motions with moment magnitudes of 5 and 6 are in good agreement with the records of strong ground motions.Among the five selected empirical attenuation relationships,the results for the ground motion with a moment magnitude of 5 are the best for its average value,and the standard deviation is the smallest.The far-field results for the attenuation relationship of ground motion with a moment magnitude of 7 are higher than most strong ground motion records.

关 键 词：测震记录 地壳介质参数 微遗传反演 地震动衰减关系 

分 类 号：P315[天文地球—地震学]