【摘要】 利用山东数字地震台网记录到的胶东半岛及附近地区2010年以来的地震波形资料,采用Brune模型,并结合遗传算法反演了本区134次2.0级以上地震的震源波谱参数。结果表明胶东半岛地区中小地震的地震矩在9.76×1011～5.9×1014 N.M之间;应力降范围在0.017～25MPa之间,均值是0.97MPa;视应力范围在0.06～10.2MPa,平均应力水平在0.396MPa。地震矩、应力降和视应力都与震级呈正相关关系,拐角频率与震级的关系不是很明显;地震矩和拐角频率成负相关关系。根据本区震源参数和震级的定量统计关系,去除震级影响,通过应力降和视应力随时间的变化得到目前正处于应力的释放时期。更多还原

【Abstract】 Source parameters calculations are generally carried out in the frequency domain.Seismic wave data from station records can be used for site response,instrument response,geometric diffusion path attenuation,and focal radiation directivity factor correction.A genetic algorithm can be used to obtain the parameters of low-frequency spectral amplitude limit and corner frequency,and thus,the theoretical formula for calculating stress drop,source radius,and seismic moment.The geological structure of Jiaodong Peninsula is complex.The area spread by the Jiaodong fault was uplifted,and the area of the northern Yellow Sea fault was bent,so the Jiaodong Peninsula fault structure is mainly monoclinic or relief synclinic.Brittle faults are well developed,mainly related to the eastern section of the Yanshan-Bohai fault zone.In contrast,at the intersection with the Tan-Lu fault in the Bohai are two sets of faults in the NNE-NE and NWW directions.The faults in the area are strong,and the structure is extremely complex;this was a high activity area in the North China earthquake.In recent years,the seismic activity has concentrated and strengthened.Regional stress changes have been analyzed in recent years in order to study the risk to Jiaodong Peninsula of strong earthquakes.Based on digital seismograms of Jiaodong Peninsula and the surrounding areas recorded by the Shandong digital seismic network since 2010,the Brune model,combined with a genetic algorithm,has been used to calculate the spectral parameters of 134 earthquakes above 2.0 in the Jiaodong Peninsula.Results show that seismic moments were between 9.76 × 1011 N·m and 5.9 × 1014 N·m;pressure drops were between 0.017 MPa and 25 MPa(0.97 MPa mean);and apparent pressures were between 0.06 MPa and 10.2 MPa(0.396 MPa mean).Seismic moment,stress drop,and apparent stress were positively correlated with magnitude,with the magnitude of the rise increasing.By using a linear fit of robust regression functions,a quantitative relationship has been developed for the Jiaodong Peninsula,which is consistent with the findings of other scholars.The relationship between corner frequency and magnitude is not obvious;seismic moment and corner frequency were negatively correlated.According to the quantitative statistical relationships between the Jiaodong Peninsula source parameters and magnitude(in addition to the effect of magnitude),and by the changes in stress drop and apparent stress over time,we can clearly see that a Jiaodong Peninsula stress adjustment has caused the stress to currently be in a period of weakening,compared to its previous high-stress state.更多还原