青岛崂山地区环境应力与视应力变化分析

利用青岛市地震监测中心数字台网的地震波形记录,选取震级下限为ML1.0,计算了2003~2004年崂山地震序列过程中青岛地区地震视应力aσpp和环境剪应力τ0值的变化,结果表明,崂山地震序列的中等地震发生前相近震级小震所反映出来的应力增强变化并不明显,2003年以来青岛地区背景应力场也不存在明显的趋势性变化。对青岛崂山地震序列中261个小震的数字化波形记录计算分析后发现,环境剪应力0τ值和视应力aσpp值与震级明显相关,并且相同震级的地震事件所计算出二者的变化与地震序列的活动状态密切相关。

Analysis on variation of ambient shear stress and apparent stress at Laoshan,Qingdao area

Using earthquake waveform records from numeric network in Qingdao Earthquake Monitoring Center,and setting the lower limit as M_L1.0,this paper calculate the variation of ambient shear stress and apparent stress in Qingdao area from 2003 to 2004.The result indicates that the raising change of stress reflected from small earthquakes with similar magnitude before moderate-earthquakes in the Laoshan sequence is not obvious,and the background stress field of Qingdao area does not show a clearly tendency change since 2003.It can be also found from the calculation and analysis that the values of ambient shear stress and apparent stress are correlative with magnitude,and the variation of these two stresses is clearly interrelated with activity behavior of the earthquake sequence.