| 长岛震群震源谱参数反演和震源参数特征 |
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| 引用本文： | 张正帅,周晨,郑建常,刘承雨. 长岛震群震源谱参数反演和震源参数特征[J]. 地震, 2022, 42(1): 85-98. DOI: 10.12196/j.issn.1000-3274.2022.01.006 |
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| 作者姓名： | 张正帅 周晨 郑建常 刘承雨 |
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| 作者单位： | 山东省地震局,山东济南 250014;黑龙江省地震局,黑龙江哈尔滨 150090 |
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| 基金项目： | 中国地震局震情跟踪青年任务(2020010120); 中国地震局震情跟踪面上任务(2020020102); 山东省地震局信息化建设与智能服务(ZD202001) |
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| 摘 要： | 采用高频截止(High-Cut)震源模型，以均方根误差最小原则稳健地求解震源谱参数，并由此推算震源尺度和静态应力降。实际应用显示，该模型的理论谱对观测谱有很好的拟合，可明显改善拐角频率识别准确度。计算了长岛震群内71次ML≥2.5地震事件的震源参数，结果表明：(1)拐角频率处于2～10 Hz范围，与震级大小存在一定的相关性，截止频率范围处于10～30 Hz之间，与地震大小的相关性不明显；(2)地震矩M0分布在1012～1014 N·m,与震级ML存在正相关关系：logM0=0.977ML+10.186;ML与矩震级MW之间的关系为：MW=0.651ML+0.766;(3)根据相对应力降时域演化发现，自2017年3月3日ML4.5地震之后应力快速释放，应力降水平在均值附近波动，而且多数ML≥3.5地震发生于...
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| 关 键 词： | 拐角频率 震源参数 应力降 长岛震群 |
| 收稿时间： | 2020-05-25 |
| 修稿时间： | 2020-10-09 |
Inversion of Seismic-Source Spectral Parameters and Characteristics of the Source Parameters for Changdao Swarm |
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| ZHANG Zheng-shuai,ZHOU Chen,ZHENG Jian-chang,LIU Cheng-yu. Inversion of Seismic-Source Spectral Parameters and Characteristics of the Source Parameters for Changdao Swarm[J]. China Earthguake Engineering Journal, 2022, 42(1): 85-98. DOI: 10.12196/j.issn.1000-3274.2022.01.006 |
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| Authors: | ZHANG Zheng-shuai ZHOU Chen ZHENG Jian-chang LIU Cheng-yu |
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| Affiliation: | 1. Shandong Earthquake Agency, Jinan 250014, China;
2. Heilongjiang Earthquake Agency, Harbin 150090, China |
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| Abstract: | Based on the Brune Model, we propose a High-Cut model by introducing the cut-off frequency fmax. We use a two-step inversion method to fit the observed seismic-source spectra and resolve its characteristic parameters. The seismic-source observation spectrum of 71 ML≥2.5 events of the Changdao swarm was obtained by the Fast Fourier Transformation. The results demonstrate that ① the method can improve the accuracy of spectra parameters significantly. The range of corner frequency of the Changdao swarm is 2~10 Hz, and there is a certain correlation between the stress drop and the moment magnitude. The range of high-frequency is 10~30 Hz, and the relationship between high-frequency and the magnitude of the earthquake is not very obvious. ② Seismic moments of events vary from 1012 N·m to 1014 N·m with increase of the magnitude, and the scaling relationship between seismic moment (M0) and magnitude (ML) for the region is logM0=0.977ML+10.186. Besides, the scaling relationship between moment magnitude (MW) and magnitude (ML) for the region is MW=0.651ML+0.766. ③ According to the time-domain evolution of relative stress drop, it is found that stress has been released rapidly after the ML4.5 earthquake on March 3, 2017, and the level of stress drop has fluctuated around the mean value, and most ML≥3.5 earthquakes occur in the process of recovery after the decrease of stress drop. ④ The range of stress drop is between 0.01 and 1 Mpa. The statistical relationship between stress drop and magnitude is: logσ =1.158ML-6.591. Moreover, the stress drop increases with magnitude, which is consistent with the result gained by Nuttli that intraplate earthquake follows the ISD model. The stress drop level of the Changdao swarm is obviously low, which reflects the low level oftectonic seress in the epicenter region. But it can be seen that the small and medium earthquakes are active in this region, it is speculated that there are two reasons. Firstly, the Bohai M7 earthquake in 1548 caused the weakening of medillm strength surmoueling focal area in Changdao region. Secondly, the faults in Bohai sea are easy to be peretrated by seawater, which resulting in the increase of pore pressure and decrease of fault strevgth, which leads to a decrease in the shear stress within the fault, and finally causes the frequent earthquake activity at Changdao region with relative lower tectonic stress. |
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| Keywords: | Corner frequency Source parameters Stress drop Changdao swarm |
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