地震研究

基于Brune模型,使用高频截止方法估计模型参数,得到2023年8月6日山东省德州市平原M_S5.5主震及部分M_L≥2.0余震的震源谱的特征参数,对不同震源参数之间的定标关系以及视应力的时空特征进行了分析讨论,结果显示:①主震视应力约为1.71 MPa,应力降约为3.51 MPa,矩震级为5.2,拐角频率约为0.58 Hz; ②平原地震序列视应力与震级存在线性关系,可表示为:lg δ_app=0.64M_L+2.92; ③余震视应力随时间发展逐渐减小,38次余震的视应力均小于0.15 MPa,低于鲁西地区小震平均视应力(0.16 MPa)。

On August 6,2023,a 5.5-magnitude earthquake occurred in Pingyuan County of Dezhou City,Shandong Province.On the basis of the Brune model,we take the minimum absolute residual between the theoretical source spectrum and the observed source spectrum as the objective function,and estimate the model parameters by using the high-cut method.Then we obtain the characteristic parameters of the source spectrum of the mainshock and some aftershocks(M_L≥2.0).We further analyze the scaling relationship between different source parameters and the spatio-temporal characteristics of apparent stress.The conclusions are as follows:①The apparent stress of the mainshock is about 1.7 MPa.The stress drop is about 3.5 MPa.Moment magnitude(M_W)is 5.2.Corner frequency(f_c)is about 0.58 Hz; ② For the Pingyuan earthquake sequence,its magnitudes have good linear relations with the corresponding apparent stress:lgδ_app=0.64M_L+2.92; ③The aftershocks' apparent stress gradually decreases with time.The apparent stress of the 38 aftershocks is under 0.15 MPa,lower than the average apparent stress(0.16 MPa)of the small earthquakes in western Shandong.

引言
1 研究区概况
2 计算方法
3 结果与讨论
4 结论

图1 平原MS5.5地震序列震中及主要断裂分布(a)和M-t图(b)<br/>Fig.1 Distribution of the epicenters of the Pingyuan MS5.5 earthquake sequence and major faults(a) and the M-t diagram of the Pingyuan earthquake sequence(b)[JZ)]

图1 平原MS5.5地震序列震中及主要断裂分布(a)和M-t图(b)
Fig.1 Distribution of the epicenters of the Pingyuan MS5.5 earthquake sequence and major faults(a) and the M-t diagram of the Pingyuan earthquake sequence(b)[JZ)]

图2 平原MS5.5地震计算实例<br/>Fig.2 A calculation example of the Pingyuan MS5.5 earthquake

图2 平原MS5.5地震计算实例
Fig.2 A calculation example of the Pingyuan MS5.5 earthquake

图3 平原MS5.5地震序列余震视应力(a)及发展趋势(b)<br/>Fig.3 The apparent stress of the aftershocks(a) and its variation tendency(b)of the Pingyuan MS5.5 earthquake sequence

图3 平原MS5.5地震序列余震视应力(a)及发展趋势(b)
Fig.3 The apparent stress of the aftershocks(a) and its variation tendency(b)of the Pingyuan MS5.5 earthquake sequence

图4 平原MS5.5地震序列余震震级与视应力的关系<br/>Fig.4 The relationship between the magnitudes of the aftershocks of the Pingyuan MS5.5 earthquake sequence and the apparent stress

图4 平原MS5.5地震序列余震震级与视应力的关系
Fig.4 The relationship between the magnitudes of the aftershocks of the Pingyuan MS5.5 earthquake sequence and the apparent stress

表1 平原MS5.5地震及ML≥3.0余震震源参数<br/>Tab.1 Source parameters of the Pingyuan MS5.5 earthquake and some aftershocks(ML≥3.0)

表1 平原MS5.5地震及ML≥3.0余震震源参数
Tab.1 Source parameters of the Pingyuan MS5.5 earthquake and some aftershocks(ML≥3.0)

图5 平原MS5.5地震余震震级和鲁西地区中小地震(2.0≤ML≤4.0)的震级与视应力的关系<br/>Fig.5 The relationship between the apparent stress and the magnitude of the Pingyuan MS5.5 aftershocks and the 2.0≤ML≤4.0 earthquakes in western Shandong

图5 平原MS5.5地震余震震级和鲁西地区中小地震(2.0≤ML≤4.0)的震级与视应力的关系
Fig.5 The relationship between the apparent stress and the magnitude of the Pingyuan MS5.5 aftershocks and the 2.0≤ML≤4.0 earthquakes in western Shandong

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备注

引言

1 研究区概况

2 计算方法

3 结果与讨论

4 结论

期刊信息